Comparative Cytokine Release from Human Monocytes, Monocyte-Derived Immature Mast Cells, and a Human Mast Cell Line (HMC-1)

Comparative Cytokine Release from Human Monocytes, Monocyte-Derived Immature Mast Cells, and a Human Mast Cell Line (HMC-1) Jiirgen Grabbe, Pia Welker, Annelie Moller, Edgar Dippel, Leonie K. Ashman,* and Beate M. Czarnetzki Department of Dermatology, University Clinics Rudolf Virchow, Free University, Berlin, Germany; and 'Department of Microbiology and Immunology, University of Adelaide, Adelaide, Australia.

To obtain further information regarding the role of cytokines during mast cell diflFerentiation, we have investigated changes of cytokine secretion in mast cells developing from the human peripheral blood monocytic cell fraction during culture -with fibroblastderived conditioned media. The influence of stem cell factor and an antibody to the respective receptor in our culture system was studied as well. Interleukin (IL)-la, IL-1)?, IL-6, and tumor necrosis factor (TNF)a were spontaneously secreted by cultured cells at day 1 and decreased markedly by day 14. Similar changes occurred also during culture w^ith stem cell factor and were partially abrogated by an anti-receptor antibody. IL-8 was secreted at a high level

throughout the culture, w^hereas no spontaneous secretion of IL-2, IL-3, IL-4, and IL-7 was measured at all. Upon stimulation w^ith phorbol myristate acetate and A23187, cultured cells showed substantially more release of IL-3 and TNF-a after 14 d of culture, compared to peripheral blood monocytic cells. Preformed TNF-a was found in one of three monocytic cell preparations from peripheral blood, but not in monocytic cell-derived mast cells. During mast cell differentiation, cytokines from monocytic cells are therefore downregulated while the cells assume a pattern typically found in mast cells. Key words: mast cett differentiation/SCF/TNF-a/tryptase. J Invest Dermatol 103:504508, 1994

M

supernatants of a mouse fibroblast cell line (L-cells) (LCS), but not under serum-free conditions. Mast cell maturation was proven by the development of metachromasia with toluidine blue, by staining for chloroacetate esterase, by tryptase activity, by increasing histamine contents, and, using immunohistochemistry, by demonstrating the expression of mast cell markers such as the a-chain of the high affinity immunoglobulin (Ig)E receptor and the c-kit protein [12-14].t In more recent studies, we could show that culture of PBMC with HS, and with SCF added instead of LCS, also results in an increase of cells positively staining for the a-chain of the FceRI (antibody 29C6) [15] and the mast cell-specific tryptase (antibody AAl) [16]. Cultures with conditioned medium (HS/LCS) plus an SCF-receptor antibody (YB5.B8) [17] led to a distinct decrease of 29C6- and AAl-reactive cells.t To explore the role of various cytokines known to influence mast cell development in the murine system [4-6], we investigated spontaneous and stimulated release of a number of cytokines from monocytic cells at the beginning and after 2 - 8 weeks of culture in the presence of HS/LCS. The pattern of cytokine secretion from these in vitro differentiated mast cells was compared to that of a human mast cell line, HMC-1. §

ast cells play an important role in immediate hypersensitivity responses, and their numbers are increased in a broad spectrum of pathologic conditions. Until now, little has been known about factors controlling mast cell proliferation and differentiation [1-3], and better knowledge of these processes might provide insights into the involvement of these cells in tissue physiology and pathology. Various cytokines {interleukin [IL]-3, IL-4, IL-9, IL-10 and more recently stem cell factor [SCF]) [4,5] have so far been shown to influence murine, and in the case of SCF, also human mast cell differentiation from bone marrow and umbilical cord blood progenitor cells [6,7]. In the human system, SCF seems to be a decisive factor in mast cell differentiation. The receptor for SCF is encoded by the c-kit proto-oncogene [8,9]. Mouse strains with a genomic defect for c-kit or SCF have a profound deficiency of mast cells [10,11]. We have previously shown that in vitro, mast cells differentiate from the peripheral blood monocytic cell (PBMC) fraction in the presence of conditioned medium containing horse serum (HS) and

Manuscript received August 4, 1993; accepted for publication June 3, 1994. These results were presented in part at the AAAI meeting in Chicago (J All Clin Immunol 91:205, 1993 [abstr]) and at the 23rd Annual Meeting of the ESDR in Amsterdam (J Invest Dermatol 100:469, 1993 [abstr]). Reprint requests to: Dr. J. Grabbe, Freie Universitat Berlin, RudolfVirchow Clinics, Department of Dermatology, Augustenburgerplatz 1, D 13344 Berlin, Germany. Abbreviations: HS, horse serum; LCS, L-cell supernatant; PBMC, peripberal blood monocytic cells; SCF, stem cell factor, SFM, serum-free medium.

0022-202X/94/S07.00

t Grabbe J, Welker P, Bauer E, Nordheim R, Czarnetzki BM: Mast cell characteristics induced byfibroblastsin different myeloid and immature mast cells (ahstr). f Invest Dermatol 98:824, 1992.

t Grabbe J, Welker P, Moller A, Czarnetzki BM: Influence of stem cell factor on mast cell differentiation from buman monocytes (abstr). Exp Dermatol 1:93, 1992.

§ Moller A, Haman K, Artuc M, Lippert U, Grabbe J, Czarnetzki BM: Cytokine production of buman mast cells (abstr). Exp Dermatol 1:93, 1992.

Copyright © 1994 by The Society for Investigative Dermatology, Inc. 504

VOL. 103. NO. 4 OCTOBER 1994

MAST CELL CYTOKINES

505

Table I. Spontaneous Cytokine Release in Culture Supernatants of PBMCs Differentiating into Mast Cells Day of Culture 1

6

13

13

52

SFM

HS/LCS

Culture With Cytokine" I L - l a (pg/ml) IL-l/?(pg/ml) IL-6 (ng/ml) IL-8 (^g/ml)

TNF-a (pg/ml)

HS/LCS 27.50 41.00 6.90 0.21 76.20

± 0.80 ± 1.50 ± 0.20 ±0.01 ± 2.80

HS/LCS 19.60 3.80 1.20 0.19 14.00

±0.70 ±0.10 ±0.05 ±0.01 ±0.50

HS/LCS 14.30 3.60 1.00 0.20 5.00

± 0.50 ±0.10 ±0.02 ± 0.01 ± 0.20

18.30 79.00 2.00 0.14 62.00

±0.600 ± 2.300 ±0.100 ±0.006 ± 0.300

•

0.00 0.00 0.10 ±0.002 0.19 ±0.005 4.00 ±0.100

* Data are expressed as amount of mediators/lO^ viable cultured cells (mean ± range of duplicate; two samples of 200/zl each were taken per point).

Furthermore, SCF and an SCF-receptor antibody (YB5.B8) were studied in our culture system regarding their efFects on cytokine release. T h e present data show that mast cells cultured from PBMCs reveal the cytokine pattern typically found in human mast cells.§ Furthermore, the findings provide first insights into a potential autocrine role of mediators secreted hy the differentiating cells. MATERIALS AND METHODS Culture Media Supernatants were obtained from confluent cells of a murine fibroblast cell line (L-cells) after 5 d of culture in Dulbecco's minimum essential medium (DMEM) (Gibco, Eggenstein, Germany) with 5% newborn calf serum (NCS). HS and NCS were purchased from Seromed, Berlin, Germany. Serum-free medium (SFM) consisted of Iscovc's modified Dulbecco's medium (Seromed, Berlin, Germany) supplemented with bovine serum albumin (1.2 mg/ml), transferrin (33.4 /ig/nil), and soybean lipids (2.4 flg/m\) (Boehringer, Mannheim, Germany). Cells PBMCs were prepared from peripheral blood offivehealthy donors by differential centrifugation on FicoU-Hypaque and adherence to polystyrene culture flasks. Nonadherent cells were removed from the flasks by washing with phosphate-buffered saline (PBS). The adherent cell fraction consisted of 80- 95% CD 14-positive cells before culture, as determined by fluorescence-activated cell sorter (FACS) analysis. Determination of mast cells was done by immunohistochemistry, using the tryptase-specific monoclonal antibody AAl, kindly provided by Dr. A.F. Walls. The hutnan mast cell line HMC-1 was kindly provided by Dr. J.H. Butterfield, Minneapolis, M N [18). Cell Culture PBMCs were incubated in SFM, with 30% LCS or recombinant human SCF (5 or 50 ng/ml) (kindly provided by Dr. M. Brockhaus, Hoffman-La Roche Ltd., Basel, Switzerland) and with 30% HS for up to 52 d, with changes of conditioning media every other day. In cultures with cells from two donors, an SCF-receptor antibody (YB5.B8) (2/ig/ml) was added to the media at days 0 and 7. An antibody of the same isotype (anti-desmin) (Dako, Denmark) (2 /ig/ml) was used as control. Both antibodies had been purified by high-performance liquid chromatography (HPLC) and extensively dialyzed. Viability at day 0 and at the end of in vitro culture was determined by trypan blue exclusion and was >90% at day 0 and 40-60% after 14 and 52 d of culture, after cell harvest. HMC-1 were cultured in RPMI medium (GIBCO) with 10% FCS (Seromed, Berlin, Germany) and 10~^ M monothioglycerol (Sigma, Deisenhofen, Germany). Cell Stimulation The adherent cells were harvested by scraping from culture flasks (at days 0 and 14), and adherent and nonadherent cells of day 14 cultures were pooled. Viable cells (1 X lOYml) in RPMI were stimulated in 24-well polystyrene plates for cytokine release with a combination ot phorbol myristate acetate (PMA) (25 ng/ml) and A23187 (0.2 fiM) (both from Sigma) for 24 h at 37°C. HMCl cells were stimulated the same way. Measurement of Cytokines Cytokines (ILs 1-4, ILs 6-8, tumor necrosis factor [TNF]-a) in cell supernatants or cell lysates (prepared by three cycles of freeze-thawing) were quantified by enzyme-linked immunosorhent assay (ELISA) (Quantikine, Fa. Biermann, Bad Nauheim, Germany), and data were expressed as means of two values calculated for 10^ viable cells. Data of duplicate measurements fluctuated within a very narrow margin (<5%). Statistics Statistical significance was calculated with an unpaired twotailed t test. Spontaneous cytokine release and mast cell numbers in culture were evaluated by calculation of the correlation coeflicient.

RESULTS

Release of Cytokines During Culture of PBMCs

Prior to

addition to cultures, the conditioning media themselves were analyzed for cytokine contents and were found to be negative for all cytokines studied here except for trace amounts of IL-8 in HS (1.8 pg/ml) and in LCS (0.06 pg/ml). These values are 100 times lower than those measured in culture supernatants. Based on tryptase staining, the percentage of mast cells at different days of culture was day 0 = 0%, day 13 = 42 ± 22%, day 52 = 51 ± 25% (n = 5). Contents of various cytokines in the supernatants of PBMCs cultured for 24 h and for up to 52 d were measured in five different experiments. IL-2, IL-3, IL-4, and IL-7 were not detected in the PBMC culture supernatants at any timepoint, whereas measurable levels of IL-la, IL-ly?, IL-6, and T N F - a were noted on day 1 (Table I, representative data from one donor). The levels of these four cytokines decreased reproducibly (Table II) up to day 52 of culture. High levels of IL-8 were measured as well, but they remained constant throughout culture (Tables I and II). To evaluate the role of serum factors in the conditioning medium, cells from the same donors were also cultured in SFM. After 13 d of culture, only a minimal upregulation of mast cell markers could be detected iminunohistochemically (only 2 ± 2% mast cells at day 13). Cytokine levels in the supernatants of SFM cultures also generally declined after 2 weeks, compared to day 1, with the exception of IL-ly?. Compared to culture in HS/LCS on day 13, values for IL-la, IL-ljS, IL-6, and T N F - a were, however, higher (Table I). The correlation between the decrease of spontaneous IL-la, IL1/?, IL-6, and TNF-a release and the number of tryptase-positive mast cells was significant (p < 0.05) when data from all experiments under different culture conditions were analyzed (n = 9)

(Table III). Stimulated Cytokine Release

Prior to culture, PBMCs re-

leased measurable quantities of IL-la, IL-1/?, IL-6, IL-8, and TNF-a after stimulation with a combination of PMA/A23187 for 24 h (Table IV). Secretion of IL-la, IL-1/?, and IL-6 was markedly

Table II. Changes in Cytokine Contents of Culture Supernatants" Cytokine

IL-la IL-lyS IL-6 lL-8 TNF-a

Percent Reduction' 40.8 ± 7.4' 89.2 ± 11.2' 81.7 ± 9 . 1 ' 3.8 ± 0.5'' 91.6 ± 10.3'

' Experiments with cells from five different normal donors, cultured with HS and LCS. ' Reduction of cytokine levels (means ± SD) at day 13 of culture, compared to levels at day 1, set at 100%. 'p<0.001. ' Not significant.

506

THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

GRABBE BT AL

Table III. Correlation of Changes in Spontaneous Cytokine Release with the Number of Tryptase-Positive Cells Cytokine

Correlation

Significance (p)

0.84 0.80 0.72 0.82

< 0.001 <0.01 <0.05 <0.01

IL-la

IL-ly? IL-6 TNF-a

lower in cultured cells (p < 0.05). In contrast, the capability of the cells to release IL-3 and TNF-a increased by day 13 (p < 0.05). The increase of IL-8 release was not significant. Stimulation of the human mast cell line HMC-1 in the same fashion showed no or lower secretion of IL-la, IL-ly?, and IL-6, compared to PBMCs (Table IV). The amount of IL-8 secreted by the three cell types was comparable, and production of IL-3 and TNF-a was higher in cultured mast cells compared to PBMCs. In PBMCs held in SFM, stimulated release of IL-la, lL-lfi, and IL-6 decreased as well during culture, whereas secretion of TNF-a increased slightly and that of IL-3 and IL-8 remained unaffected. Comparing cytokine secretion by PMBCs cultured in HS/LCS versus SFM, significant differences were noted only for IL-3 and

TNF-a (Table IV). Influence of SCF on Cytokine Release To examine whether SCF had the same effect as LCS on cytokine secretion from PMBCs, spontaneous cytokine release was measured from cells kept in H S / LCS, HS + SCF (5 ng/ml), and HS + SCF (50 ng/ml) (Fig 1). The percentages of mast cells in these experiments were day 0, 0%; day 13 (30% LCS), 22 ± 12%; day 13 (5 ng SCF), 39 ± 15%; day 13 (50 ng SCF), 46 ± 18% (n = 3). Addition of SCF (5 or 50 ng/ml) caused a marked decrease of spontaneous IL-la (Fig la), IL-ly3 (Fig lfc), and T N F a (Fig lc) release on days 6 and 13, compared to cells after 1 d of culture (p < 0.022). For IL-lfi (Fig I t ) , more cytokine release was noted during the first day of culture in SCF, compared to LCS (p < 0.04). Levels of IL-la and TNF-a at days 6 and 13 of culture in SCF were lower compared to LCS (p < 0.02), whereas the effect of LCS and SCF on spontaneous secretion of IL-6 and IL-8 was equal throughout culture (data not shown). A clear dose dependency between the effects of 5 and 50 ng SCF/ml could not be established. To provide further evidence that the effects observed regarding cytokine secretion of PBMCs differentiating towards mast cells were indeed due to SCF, an antibody against the SCF receptor (YB5.B8) was added to the conditioning media containing H S / LCS at days 0 and 7 of culture. The percentages of mast cells in the two experiments done were day 0, 0%; day 13 (without antibody), 30%; day 13 (antibody YB5.B8), 10% (n = 2). The SCF-receptor antibody partially prevented the decrease of IL-la, IL-lyS, and TNF-a as normally observed during culture.

whereas no effect was noted on IL-6 and IL-8 release. An irrelevant antibody of the same isotype had no effect (data not shown). Studies on Preformed TNF-a In the literature, T N F - a has been described as being stored preformed within mast cells [19,20]. We therefore tried to detect preformed TNF-a in freshly prepared PBMCs and in mast cells that had developed after 2 weeks of in vitro culture with HS/LCS from PBMCs. Cell lysates and supernatants were analyzed before and after 1 h of stimulation with a combination of PMA/A23187. After 2 weeks of culture, unstimulated and stimulated cells from three different normal donors contained no preformed TNF-a in cell lysates and cell supernatants. Only in freshly prepared PBMCs from one of the three donors could TNF-a be detected (107 pg/10* cells in the lysate of unstimulated cells). There was 50 pg/ml released into the supernatants by the cells of this donor after 1 h of stimulation with PMA/A23187. DISCUSSION In this study, we have investigated the cytokine secretion pattern of monocytic cells differentiating into immature mast cells during culture with HS/LCS. We demonstrate that during the course of culture, the cells change their pattern of spontaneous and stimulated cytokine release to that of immature mast cells, as exemplified by the immature mast cells of the HMC-1 line. In previous experiments, we have reported that under the influence of fibroblast-derived factors, cells from the monocytic fraction of human peripheral blood and monocytic and promyelocytic cell lines develop histochemical, immunohistochemical, and functional characteristics of mast cells [12,13]. The percentage of the original adherent cell population developing mast cell characteristics varies, depending on the investigated mast cell markers and the individual donors. Maturation of an immature mast cell line can be induced as well [13].t One of the decisive factors in mast cell differentiation and maturation may be SCF, also named mast cell growth factor [8].t SCF was originally identified as the gene product of the murine steel locus on chromosome 10 and as a ligand for the c-kit protein [9,10]. It has been shown to be a potent stimulator of mast cell growth and granule protein synthesis in murine bone marrow cells [21]. Valent et al have reported similar effects after 4 weeks of human bone marrow and peripheral blood mononuclear cell culture with SCF [8] and SCF has been shown to generate and maintain immature, mucosa-type mast cells in 14-week culture of human cord blood cells [22]. We have studied this factor for its effect on human peripheral blood monocytic cells in our culture system and have shown previously that all tested mast cell characteristics were markedly upregulated, while an antibody to the SCF receptor had a partially downregulating effect.:j: Our data suggest that SCF is a definite but not a unique factor for human mast cell differentiation. In the murine system, the participation of other cytokines in the differentiation process has been studied extensively, with IL-3, IL-

Table IV. Stimulated Cytokine Release from Different Cell Types (Means ± SD) PBMCs, 13-d Culture Cytokine IL-la (pg/ml) IL-1^ (pg/ml) IL-3 (ng/ml) IL-6 (ng/ml) lL-8 (/ig/ml) TNF-a (ng/ml)

PBMCs (fresh)

In HS/LCS"

In SFM'

HMCl

(n = 3)

(n = 3)

(n = 3)

(n=l)

10.40 ± 4.90'' 76.20 ±41.0^ 0.57 ± 0.200.37 ±0.10'' 0.19 ±0.02' 1.36 ± 0.30'

14.2 ± 4.7' 81.3 ± 12.2' 0.00 ± 0.00' 0.80 ± 0.30' 0.13 ±0.04' 0.60 ±0.15'

27.40 ± 5.20 344.00 ± 185 0.00 ± 0.00 3.80 ± 1.50 0.14 ±0.05 0.25 ±0.10

• Statistical significance was calculated comparing fresh with cultured PBMCs. * Statistical significance was calculated comparing cultured PBMC in HS/LCS versus SFM. 'p<0.01. ^ p < 0.05. ' Not significant.

0.00 22.00 0.50 2.80 O.IS

2.60

MAST CELL CYTOKINES

VOL. 103, NO. 4 OCTOBER 1994

507

« 140

m 35

o %

30

O)

o.26 20

15

10

a

b

c

a

day 1

b

c

day 6

a

b

c

day 13

a

b

c

day 6

a

b

c

day 13

o O

80 Figure 1. Time course of spontaneous cytokine release from PBMC and PBMC-derived mast cells. Cytokines (mean ± SD from data) were determined in eulture supernatants on days 1, 6, and 13. Cultures were done in HS/LCS (a), HS/SCF (5 ng/ml) (b) or HS/SCF (50 ng/ml) (c). a) IL-la, b) IL-1^, c) TNFa.

60 i- . .

I

40

T

20

a

b

day 1

c

a

b

c

day 6

4, IL-6, IL-9, IL-10, nerve growth factor (NGF), and granulocytemacrophage colony stimulating factor (GM-CSF) all being reported to influence the maturation or proliferation of mast cells [4-6]. In the human system, only a few studies reporting effects of these factors have been published. Sillaber et al showed that IL-4 downregulates the expression of the c-kit gene product in human mast and myeloid progenitors cells [23]. The effect of IL-3 is controversial; Kirshenbaum et al [7] described the production of basophils and mast cells from CD34-positive cells with IL-3, whereas Valentef a/found no effect of IL-3, IL-4, IL-9, and GM-CSF on mast cell differentia-

tion from bone marrow and peripheral mononuclear cells [8]. IL-3, but no other cytokine, stimulated, on the other hand, basophil differentiation in this system [24]. In the present studies, IL-2, IL-3, IL-4, and IL-7 were not detected in the supernatants of the cultured and differentiated cells. It is therefore unlikely that these factors play an important role in the differentiation of monocytic cells towards mast cells in our culture system. We could show, however, that the concentrations of IL-la, IL-1;?, IL-6, and TNF-a decreased in culture with HS/LCS, in parallel with an increase of mast cell characteristics. It remains to be

508

THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

GRABBE ET AL

determined whether the addition of these cytokines to cultures or the blocking of these effects influences the differentiation process. In preliminary work with IL-6, this seems indeed to be the case.Tl On the other hand, the concentration of IL-8 remained almost constantly at a high level throughout the culture so that a modulating effect on the mast cell differentiation process by this cytokine remains possible but seems less likely. In serum-free cultures, decreased concentrations of IL-la and IL-6 were observed after day 13, compared to cultures on day 1. TNF-a levels were higher than in HS/LCS cultures, and IL-lyS levels were even above those on day 1 (Table I). Because scarcely any mast cell development was observed in SFM, the altered cytokine levels may be a reflection of non-mast cells releasing these factors. Because SCF is present in the HS/LCS cultures, and as it is known to stimulate mast cell secretion [25], the altered cytokine levels in the SFM culture supernatants may reflect the lack of SCF action. In addition to the spontaneous cytokine secretion, changes were also noted in the pattern of stimulated cytokine release from cultured, differentiating mast cells, compared to the initial cell population in culture. The monocyte-derived mast cells resembled the human immature mast cell line HMC-1, with a lower release of IL-la, IL-1^, and IL-6 and an increase of IL-3 and TNF-a (Table IV) compared to the seeded cells. In particular, the secretion of IL-3 and TNF-a from the cultured cells is striking because the monocytic cells released no IL-3 at all and only little TNF-a, whereas these cytokines were secreted in substantial amounts by the HMC-1 cells. Thisfitswith data from the literature where human mast cells have been shown to be potent sources of these cytokines [20].§ In the present studies, we show that SCF, in parallel with differentiation of monocytic cells towards mast cells, also induces a switch in cytokine release towards a pattern found in mast cells. The effects of HS/LCS were partially abrogated by culture with the SCF-receptor antibody YB5.B8 in two experiments, in parallel with the inhibition of mast cell development by this antibody.| These results emphasize that SCF plays an important role in mast cell differentiation and that the changes in cytokine release pattern towards that of mast cells parallel this process. The presence of preformed TNF-a is described by Gordon et al [20] and Walsh et al [21] as typical for mast cells, whereas Benyon et al [26] were unable to detect TNF-a in unstimulated skin mast cells. In our experiments, we also failed to find preformed TNF-a in the in vitro differentiated mast cells. One reason could be the immaturity of these cells or lack of stimulatory factors operative in vivo. The detection of TNF-a in lysates of freshly prepared, unstimulated monocytes from one donor may be due to unspecific activation in vivo or during the isolation procedures. In conclusion, this study supports the concept that cells in the monocytic fraction of peripheral blood can differentiate towards mast cells under the influence offibroblast-derivedfactors such as SCF, also on the basis of the cytokine pattern produced by these cells. Moreover, the presentfindingsof changing cytokine patterns during in vitro mast cell development suggest that the cultured cells themselves may regulate their differentiation. This potentially complex interaction will have to be elucidated further for each factor involved.

2. 3.

4.

5. 6.

7.

8.

9.

10.

11.

12.

13.

14. 15.

16. 17.

18. 19. 20.

21.

22.

23.

This work was supported hy a grant from the German Research Foundation. 24. We thank Mrs. Regina Nordheim and Ms. Elke Bauer for excellent technical assistance and Dr. Andrew Walls, Southampton, for providing the tryptase antibody 25. AAL

REFERENCES 1.

DesagaJF, Parwaresch MR, Mullcr-HcrmeHng HK: Die zytochemische Identifikation der Mastzellvorstufen bei der Ratte. Z Zellforsch 121:292-300, 1971

H Welker P, Grabbe J, Moller A, Czarnetzki BM: Secretion of cytokines and inhibitory role of IL-6 during human mast cell differentiation in vitro (3hst!:).J Allergy Clin Immunol 91:205, 1993.

26.

Combs J W , Laguno D, Benditt EP: Differentiation and proliferation of embryonic mast cells in tbe rat.J Cell Biol 25:577-592, 1965 Saito H, Hatake K, Dvorak AM, Leiferman KM, Dannenberg AD, Arai N, Ishizaka K, Isbizaka T: Selective differentiation and proliferation of bematopoietic cells induced by recombinant butnan intcrleukins. Proc Natl Acad Sci USA 85:2288-2292, 1988 Swietcr M, Mergenbagen SE, Siraganian RP: Microenvironmental factors that influence mast cell pbenotype and function. Proc Soc Exp Biol Med 199:22-23, 1992 Moller A, Grabbe J, Czarnetzki BM: Mast cells and tbeir tnediators in immediate and delayed immune reactions. Skin Pharmacol 4 (suppl 1):51S-63S, 1991 Tsui K, Izebo KM, Ogawa M: Murine mast cell colony fortnation supported by 113, 114 and recotnbinant rat stem cell factor, ligand for c-kit. _/ Cell Physiol 148:362-369, 1991 Kirsbenbaum AS, Goff JP, Kessler SW, Mican JM, Zsebo KM, Metcalf DD: Effect of 113 and stem cell factor on tbe appearance of buman basopbils and mast cells from CD34 and pluripotent progenitor cells. J/mww«o/ 148:772-777, 1992 Valent P, Spanblocbl E, Sparr WR, Sillaber C, Zsebo KM, Agis H, Strobl H, Geissler K, Bettelbeim P, Lecbner K: Induction of differentiation of human mast cells from bone marrow and peripheral blood mononuclear cells by rbSCF/c-kit-Ugand (KL) in long time culture. Blood 80:2237-2245, 1992 Takagi M, Nokahata T, Kubo T, Sbiohara M, Koike K, Miyajima A, Araj K-I, Nisbikawa S-I, Zsebo KM, Komiyama A: Stimulation of mouse connective tissue-type mast cells by bemopoietic stem cell factor, a ligand for c-kit receptor./JrarnHno; 148:3446-3453, 1992 Nocka K, Tan J C , Cbiu E, Chu TY, Ray P, Traktman P, Besmer P: Molecular bases of dominant negative and loss of function mutations at tbe tnurine c-kit/ white spotting locus: W " , W^, W " , and W . EMBOy 9:1805-1815, 1990 Zsebo KM, Williams DA, Geissler EN, et al: Stem cell factor is encoded at the SI locus of tbe mouse and is tbe ligand for the c-kit tyrosine kinase receptor. Cell 63:213-224, 1990 Czarnetzki BM, Figdor CG, Kolde G, Vroom T, Aalberse R, de Vries J: Development of buman connective tissue mast cells from purified blood monocytes. Immunology 51:549-554, 1984 Welker P, Grabbe J, Hakimi J, Walls AF, Ostmeier H, Czarnetzki BM: Fibroblast-derived factors induce different mast cell cbaracteristics in buman myeloid cell lines and peripberal monocytes. Int Arch Allergy Immunol 99:337 - 339, 1992 Sterry W , Czarnetzki BM: In vitro differentiation of rat peritoneal inacropbages into mast cells: an enzymecytocbemical study. Blut 44:211 - 2 2 0 , 1982 Rjske F, Hakimi J, Mallamaci M, Giffin M, Pilson B, Tobkes N , Lin P, Danho W, Kochan J, Chizzonite R: Higb affinity human IgE receptor (Fc€RI). Analysis of functional domains of tbe a-subunit witb monoclonal antibodies. J Bio Chem 266:11245-11251, 1991 Walls AF, Jones DB, Williams JH, Church MK, HolegateST: Immunobistochemical identification of mast cells in formaldehyde-fixed tissue using monoclonal antibodies specific for tryptase. J Pathol 162:119-126, 1990 Lerner NB, Nocka KH, Cole SR, Qui F, Strife A, Asbman LK, Besmer P: Monoclonal antibody YB5.B8 identifies the buman c-kit protein product. Blood 77:1876-1883, 1991 Butterfield JH, Weiler D, Dewald G, Gleich GJ: Establishment of an immature mast cell line from a patient with mast cell leukemia. Leukemia Res 12:345355, 1988 Gordon JR, Galli JS: Mast cells as a source of both preformed and immunologically inducible TNF-a/cacbectin. Nature 346:274-276, 1990 Walsh LJ, Trincbieri G, Waldorf HA, Wbitaker D, Murphy GF: Human dermal mast cells contain and release tumor necrosis factor a , which induces endothelial leucocyte adhesion molecule 1. Proc Natl Acad Sci USA 88:4220-4224, 1991 Tsai M, Takeishi T, Thomson H, Langley KE, Zsebo KM, Metcalfe DD, Geissler EN, Galli SJ: Induction of mast cell proliferation, maturation, and heparin synthesis by tbe rat c-kit ligand, stem cell factor. Proc Natl Acad Sci USA 88:6382-6386, 1991 Mitsui H, Furitsu T, Dvorak AM, Irani AM, Schwartz LB, Inagaki N, Takei M, Ishizaka K, Zsebo KM, Gillis S, Ishizaka T: Development of human mast cells from umbilical cord blood cells by recombinant human and murine c-kit ligand. Proc Natl Acad Sci USA 90:735-739, 1993 Sillaber CH, Bevec D, Asbman LK, Butterfield JH, Lechner K, Maurer D, Bettelbeim D, Valent P: 11-4 regulates c-kit gene product expression in human mast and myeloid cell progenitors.y/mrauno/ 147:4224-4228, 1991 Valent P, Schmidt G, Besmer J, Mayer P, Zenke G, Liebl E, Hinterberger W, Lechner K, Maurer D, Bettelheim P: Interleukin 3 is a differentiation factor for human basophils. BUrf 73:1763-1769, 1989 Columbo M, Horowitz EM, Botatia LM, MacGlashan D W Jr, Bochner BS, Gillis S, Zsebo KM, Galli SJ, Licbtenstein LM: Tbe buman recombinant c-kit receptor ligand, rhSCF, induces mediator release from human cutaneous tnast cells and enhances IgE-dependent mediator release from both skin mast cells and perpberal blood basophils.y/mmuno/149:599-608, 1992 Benyon RC, Bissonnette EY, Befus AD: Tumor necrosis factor-a dependent cytotoxicity of human skin mast cells is enhanced by anti-lgE antibodies, y Immunol 147:2253-2258, 1991