- Email: [email protected]
Allogenic stimulus induces prostaglandin and thromboxane production in T lymphocytes
0952.3278/89/0038-0203/S10.00
hostaghdins Leukotrienes and Essential Fatty Acids (1989) 38.203-206 fQ Longman Group UK Ltd 1989
Allogenic Stimulus Induces Prostaglandin and Thromboxane Production in T Lymphocytes A. M. GENARO,
G. A. CREMASCHI
and E. S. BORDA
Centro de Estudios Farmacoldgicos y de Principios Naturales ICEFAPRINI Consejo National de lnvesrigaciones Cientificas y Tknicas de la Reptiblica Argentina (CONKET). (Reprint requests and mailing address: ESB, Serrano 665, (1414) Buenos Aires, Argentina)
Abstract - We have examined the influence of an allogeneic stimulus on T lymphocyte prostanoid synthesis. PGEz and TXBz (the stable product of TX4) were determined by radioimmunoassay. When T cells were derived from alloimmunized animals, the production of PGEz and TXAz was significantly higher than that of non-immunized cells. Moreover, T immune lympocytes in the presence of the immunized alloantigen showed an increment in prostanoid production. We propose that the allogeneic stimulus provides a signal to the T lymphocytes for an increase in prostanoid synthesis.
Introduction
In previous reports we have demonstrated that T cells from allo-immunized mice exerted negative inotropic effects on the contractile tension of spontaneously beating mouse isolated atria (1). This effect was specific for antigens linked to the Major Histocompatibility Complex (MHC), both in their induction and their expression (1). Several experiments have indicated that this effect is mediated by arachidonic acid cyclooxygenase metabolites. Furthermore, we have demonstrated that after contact of sensitized T lymphocytes with specific alloantigens on atria1 cells, active factors are synthesized and released by immunocompetent cells (1, 2). Reports of several laboratories have implicated prostaglandins, especially prostaglandins of the
E serie, as important mediators of immunocompetent cell functions (3, 4). Although macrophages have been described as major cellular source of prostaglandins (4, 5), the role of lymphocytes as prostaglandin-producing cells is still controversial (4, 6). Rinaldi-Garaci et al. (7) have reported the induction of PGE* production by a thymic hormone in Ficoll-separated murine thymocytes and splenocytes. The purpose of the present study was to examinate if T lymphocytes are able to synthesize prostaglandins and thromboxane in response to an allogeneic stimulus. Alloimmune T cells produced PGE2 and TXB2 in significantly higher quantities than control cells. Additionally, the specificity of this phenomenon was linked to the MHC complex.
203
204
PROSTAGLANDINS
Methods Mice
Inbred male BALB/c (H-2d), C3H (H-2k), AKR (H-2k) and C57 Bl/Hep (H-2’) mice were acquired from the Comision National de Energia Atdmica (Argentina). All animals were used between 60 and 90 days of age. Immunizations
All immunizations were carried out between animals of the same sex, according to the following plan: one intradermal injection of 1 x 10’ lymphoid cells (pooled spleen, lymph node and thymus suspensions) followed at 7 day intervals by one or more immunizations with 3 x lo7 cells intraperitoneally. Mice were killed 4 or 5 days after the last injection. The degree of immunization was tested by measuring the citotoxic activity of alloimmunized sera as described previously (9). Preparation of purified T ceils
A T cell-enriched population was obtained by the method of Julius et al. (10) as described previously (1). Briefly, lymph nodes were removed and gently homogenized in RPMI-1640 with a loosely fitting teflon-glass homogenizer; the cell suspension was filtered through a metal mesh and then through needles, washed in medium and resuspended in phosphate buffered solution with 5% fetal calf serum, and passaged through nylon wool columns. The viability of the cell suspension was more than 95% as checked by trypan blue exclusion test. The degree of purification was checked by lysis with anti-Thy plus complement and/or direct immunofluorescence. By these methods more than 97% of the cells were shown to be T cells.
LEUKOTRIENES
AND ESSENTIAL
The pellets, resuspended were stored at -20°C. Measurement
FAT-I-Y ACIDS
in PBS at 2-5 mg’ml,
of PGE and TX
The amounts of PGE and TX were determined in cells and their supernatants. The cells were disrupted by sonication on ice three times for 30 set at maximum speed by using a Labsone C 1510. Both supernatants and cell suspensions were used immediately. For prostanoid assays, three extractions with chloroform at pH 4 were performed (12). Pooled chloroform extracts were dried under a stream of nitrogen gas at 40°C. The residue was dissolved in the corresponding buffer and an aliquot was taken for PGE? and TX& determinations byzysing a radioimmunoassay procedure (PGEzI RIA KIT, New England Nuclear and TXBZ-‘~“I RIA KIT, New England Nuclear). Statistical analysis
Statistical significance of differences was determined by two tailed “t” test for independent populations. When multiple comparisons were necessary Student-Newman-Keuls test was used after analysis of variance. Results PGE2 and TXB2 release by immunized normal T cells
and
As shown in Figure 1 non-immunized and alloimmunized T cells are able to generate PGE2 and TXB*. However, the productions of PGEz and TXB;! were significantly higher in alloimmune T
Preparation of supernatants
Cell free supernatants were obtained by incubation of 4 x lo7 T lymphocyte enriched cells alone or with 0.6-1.2 mg of lymphoid organ alloextracts in 1 ml of RPMI-1640 for 30 min at 37” followed by centrifugation of the cell mixture for 15 min at 500 g. Alloextracts were obtained according to the method described by Braun et al. (11). Briefly, lymphatic organs were homogenized in phosphate buffer saline (PBS) and sonicated for 10 min at 10 kc/set, lipids were extracted with chloroform and the aqueous phase recovered and centrifuged at 20.000 g for 30 min.
TXE2
PGEZ
TX&
PGE,
Fig. 1 Basal prostanoid synthesis by non-immunized (0) and immunized (m) T cells. PGE, and TXB, amounts were determined in cells (A) and in their supernatants (B) after incubation for 30 minutes at 37°C according to the experimental procedures described in Methods.
ALLOGENIC STIMULUS INDUCES PC AND THROMBOXANE PRODUCTION
205
(H-2b) alloextracts. These results show that the alloextracts must share the same H-2 specificity as the immunizing strain in order to induce T cell cyclooxygenase enzyme hyperactivity. Discussion
PGEz
1x02
PGE2
TX62
Fig. 2 PGEr and TXB, synthesis by non-immunized (0) and immunuzed (m) T-cells after exposure to specific alloantigen. Prostanoid amounts were determined in cells (A) and in their supematants (B) after incubation in the presence of alloextracts as described in the Methods.
lymphocytes than in non-immunized T cells. Balb/c anti-C&I T cells incubated with the specific C@ alloextracts produced significantly greater amounts of PGE;! and TXB:! than immune cells alone (Figure 2). Alloextracts did not modify significantly the production of PGE? or TXB2 in normal T cells (Fig. 2). Spec$city of PGE2 and TXBZ production alloimmune lymphocytes
by T
To analyze the participation of products of the Major Histocompatibility Complex (MHC) in the phenomenon, T immune cells from BALB/c mice with BALB/c anti C3H (H-2k) specificity were exposed to alloantigens from different strains. As shown in the Table we obtained an increased production of PGE2 and TXB2 with both C3H (H-2k) and AKR (H-2k) alloextracts. On the contrary, increased production of prostanoids was not obtained with BALB/c (H-2d) or C57 Bl/Hep Table
Specificity
of PGE,
and TXB, production
of
T lymphocytes Supernatans of
PGF,
TXBz (Pdb4
T T T T T
cell cell cell cell cell
alone + AlloAg C,H + AlloAg AKR + C.57 Bl/Hep + BALB/c
2.3 8.5 9.3 2.1 2.4
+ + f f 5
0.1 0.9 1.1 0.2 0.1
5.6 27.4 31.1 4.9 5.3
+ 1.0 rfI 1.2 + 1.8 f 0.9 f 1.0
Balb/c anti C,H alloimmune T cells were incubated alone or in the presence of alloextracts obtained from different strains (AlloAg). Values represent the Mean f S.E.M. of 5 separate experiments.
In this study we have shown that T lymphocytes from alloimmunized mice are able to produce higher amounts of PGE2 and TXB* than normal active T cells. This points to a more cyclooxygenase enzyme in alloimmune T lymphocytes than in normal T cells, which is responsible for the synthesis and release of PGE2 and TXB,?. Our data also show that immune T cells in the presence of specific alloantigens are abIe to synthesize and release both cyclooxygenase derived arachidonic acid products in higher amounts than T immune cells not challenged with the specific antigen. ‘The ability of lymphocytes to synthesize PGE? or TXA2 has been previously reported (7, 13, 14). The response of T cells to antigen involves a cascade of cellular events which culminates in T cell proliferation. Activation of T receptors by the specific antigen involves an increase of free cytoplasmic Ca++ concentration (15). Because changes in intracellular levels of Ca++ or Ca++ fluxes result in modifications of phospholipase activity and arachidonic acid metabolism it is tempting to speculate that stimulation of T cell receptor or associated proteins is followed by changes in arachidonic acid metabolism and prostanoid synthesis. The increased prostanoid synthesis only takes place when immune T cells are antigenically challenged with the same H-2 specificities as used for immunization. In order to obtain PGE;! or TX& products from active T cells, alloextracts must derive from H-2 compatible strains (AKR and CjH, both H-29. When alloantigens are derived from H-2 incompatible strains (BALB/c, H-2d or C57 Bl/Hep, H-2b) the production of PGEz and TXBz tends to be lower. In short, the data indicate that T cells sensitized against MHC products are able to release PGE? and TXB, during the specific recognition of a product of either the MHC or of a very closely linked gene. The bulk of evidence suggests that prostaglandins play a key role in the regulation of both humoral and cell-mediated immunity. Usually PGE acts as a feedback inhibitor of the response (13). Perhaps, the synthesis and release of PGE2 during alloantigenic recognition represent a feed-
206
PROSTAGLANDINS
back mechanism capable of regulating the response . On the other hand, the effect of TXA2 on lymphocyte function is difficult to determine because it is very labile product which is rapidly convet-ted to TXB,. Available data upon the action of TXA;! on the immune response-are contradictory and its role is still largely unknown (17, 18, 19). Experiments presented in the proceeding section as well as data published previously (2, 16) suggest that PGE2 and probably TXA;! may play some role in the alloimmune response. Further experiments are necessary to stablish the exact function of prostanoids in the alloimmune response. Acknowledgements The present study has been 3904802/85 from CONICET.
supported
by Grant.
PID
References 1. Genaro, A. M., Borda, E. S., Cremaschi, G. A., SterinBorda, L. and Braun, M. H-2 specific inotropic effect of alloimmune lymphoid cells on mouse isolated atria. Immunopharmacology 11: 129-140,1986. 2. Borda, E. S., Genaro, A. M., Peredo, H, Cremaschi, G. A., Perez-Leiros, C. and Sterin-Borda, L. Alloimmunization induced changes in thymocytes prostaglandin levels: a signal for the induction of biological activity. Int. J. Immunopharmacol. 7: 647-653, 1985. Goodwin, J. S. and Cluppens, J. Regulation of the immune response by prostaglandins. J. Clin. Immunol. 3: 295-315, 1983. Goldyne, M. E. and Stobo, J. D. Immunoregulatory role of prostaglandins and related lipids. Crit. Rev. Immunol. 2: 189-223, 1981. Humes, J. L., Salcowski, S. and Galavage, M. Evidence for two sources of arachidonic acid for oxidative metabolism by mouse peritoneal macrophages. J. Biol. Chem. 257: 1591-1594.1982. Lewis, G. P. Immunoregulatory activity of metabolites of AA and their role in inflammation. Br. Med. Bull. 39: 234-245. 1983.
7.
LEUKOTRIENES
AND ESSENTIAL FATTY ACIDS
Rinaldi-Garaci, C., Garaci, E. and Del Gabbo. U. Modulation of endogenous prostaglandins by thymosinalpha lymphocytes. Cell Immunol. 80: 57-63. 1983. 8. Braun, M., Saal, F., Pasqualini, C. D. Aspectos inmunologicos del crecimiento tumoral murino alogenico. Sangre (Barcelona) 19: 153-156. 1974. 9. Julius, M. H., Simpson, E. and Herzenberg, L. A. A rapid method for the isolation of functional thymusderive murine lymphocytes. Eur. J. Immunol. 3: 645-649, 1973. 10. Braun, M., Sen, L. Bachman, A. E. and pavlosky, A. Cell migration inhibition in human lymphomas -using lvmnh node and cell line extracts. Blood 39: 368-376, i97i. rr, Friilich, J. C., Wilson, T. W.. Sweetman. B. J.. Smigel. M., Mies, A. S. Can, K., Watson, J. T. and Oates, J. A. Urinary prostaglandins. Identification and origin. J. Clin. Invest. 55: 763-77?, 1975. 12. Parker. C. W., Stersone, W. F., Huler, M. G. and Kelly, J. P. Formation of TXB2 an hydroxyarachidonic acids in purified human lymphocytes in the presence and absence of PHA. J. Immunol. 222: 1572-1578, 1979. 13. Bauminger, S. Differences in prostaglandin formation Prostaglandins between thymocytes subpopulations. 16: 351-355,1978. 14. Aussel, C., Didier, M. and Fehlmann, M. Prostaglandin synthesis in human T cells. Its partial inhibition by lectius and anti-CD, anti bodies as a possible step in T cell activation, J. Immunol. 138: 3094-3099, 1987. 15. Inboden, J. B., Weiss, A. and Stobo, J. D. The antigen receptor an human T cell line initiates activation by incytoplasmic free calcium. J. Immunol. creasing 134: 663-668, 1985. 16. Borda, E. S., Genaro, A. M., Perez Leiros, C., Cremaschi, G., Peredo, H. and Sterin-Borda, L. Prostaglandin CAMP production and biological activity of alloimmune thymocytes. Prost. Leuk. Med. 19: 197-208, 1985. 17. Kedly, J. P., Johnson, M. C. and Parker, C. W. Effect of inhibitions of arachidonic acid metabolism on mitogenesis in human lymphocytes: possible role of thromboxanes and products of the liboxygenase pathway. J. Immunol. 122: 1563-1571, 1979. 18. Gordon, D., Noreni, A. M. E. and Thomas, R. V. Selective inhibition of thromboxane biosynthesis in human blood mononuclear cells and the effects on mitogenstimulated lymphocyte proliferation. Br. J. Pharmacol. 74: 469-475, 1981. 19 Ceuppens, J. L., Vertessen, S. Deckmyn, H. and Vermylen, J. Effects of thromboxane A2 on lymphocyte proliferation. Cell Immunol. 90: 458-463, 1985.
hostaghdins Leukotrienes and Essential Fatty Acids (1989) 38.203-206 fQ Longman Group UK Ltd 1989
Allogenic Stimulus Induces Prostaglandin and Thromboxane Production in T Lymphocytes A. M. GENARO,
G. A. CREMASCHI
and E. S. BORDA
Centro de Estudios Farmacoldgicos y de Principios Naturales ICEFAPRINI Consejo National de lnvesrigaciones Cientificas y Tknicas de la Reptiblica Argentina (CONKET). (Reprint requests and mailing address: ESB, Serrano 665, (1414) Buenos Aires, Argentina)
Abstract - We have examined the influence of an allogeneic stimulus on T lymphocyte prostanoid synthesis. PGEz and TXBz (the stable product of TX4) were determined by radioimmunoassay. When T cells were derived from alloimmunized animals, the production of PGEz and TXAz was significantly higher than that of non-immunized cells. Moreover, T immune lympocytes in the presence of the immunized alloantigen showed an increment in prostanoid production. We propose that the allogeneic stimulus provides a signal to the T lymphocytes for an increase in prostanoid synthesis.
Introduction
In previous reports we have demonstrated that T cells from allo-immunized mice exerted negative inotropic effects on the contractile tension of spontaneously beating mouse isolated atria (1). This effect was specific for antigens linked to the Major Histocompatibility Complex (MHC), both in their induction and their expression (1). Several experiments have indicated that this effect is mediated by arachidonic acid cyclooxygenase metabolites. Furthermore, we have demonstrated that after contact of sensitized T lymphocytes with specific alloantigens on atria1 cells, active factors are synthesized and released by immunocompetent cells (1, 2). Reports of several laboratories have implicated prostaglandins, especially prostaglandins of the
E serie, as important mediators of immunocompetent cell functions (3, 4). Although macrophages have been described as major cellular source of prostaglandins (4, 5), the role of lymphocytes as prostaglandin-producing cells is still controversial (4, 6). Rinaldi-Garaci et al. (7) have reported the induction of PGE* production by a thymic hormone in Ficoll-separated murine thymocytes and splenocytes. The purpose of the present study was to examinate if T lymphocytes are able to synthesize prostaglandins and thromboxane in response to an allogeneic stimulus. Alloimmune T cells produced PGE2 and TXB2 in significantly higher quantities than control cells. Additionally, the specificity of this phenomenon was linked to the MHC complex.
203
204
PROSTAGLANDINS
Methods Mice
Inbred male BALB/c (H-2d), C3H (H-2k), AKR (H-2k) and C57 Bl/Hep (H-2’) mice were acquired from the Comision National de Energia Atdmica (Argentina). All animals were used between 60 and 90 days of age. Immunizations
All immunizations were carried out between animals of the same sex, according to the following plan: one intradermal injection of 1 x 10’ lymphoid cells (pooled spleen, lymph node and thymus suspensions) followed at 7 day intervals by one or more immunizations with 3 x lo7 cells intraperitoneally. Mice were killed 4 or 5 days after the last injection. The degree of immunization was tested by measuring the citotoxic activity of alloimmunized sera as described previously (9). Preparation of purified T ceils
A T cell-enriched population was obtained by the method of Julius et al. (10) as described previously (1). Briefly, lymph nodes were removed and gently homogenized in RPMI-1640 with a loosely fitting teflon-glass homogenizer; the cell suspension was filtered through a metal mesh and then through needles, washed in medium and resuspended in phosphate buffered solution with 5% fetal calf serum, and passaged through nylon wool columns. The viability of the cell suspension was more than 95% as checked by trypan blue exclusion test. The degree of purification was checked by lysis with anti-Thy plus complement and/or direct immunofluorescence. By these methods more than 97% of the cells were shown to be T cells.
LEUKOTRIENES
AND ESSENTIAL
The pellets, resuspended were stored at -20°C. Measurement
FAT-I-Y ACIDS
in PBS at 2-5 mg’ml,
of PGE and TX
The amounts of PGE and TX were determined in cells and their supernatants. The cells were disrupted by sonication on ice three times for 30 set at maximum speed by using a Labsone C 1510. Both supernatants and cell suspensions were used immediately. For prostanoid assays, three extractions with chloroform at pH 4 were performed (12). Pooled chloroform extracts were dried under a stream of nitrogen gas at 40°C. The residue was dissolved in the corresponding buffer and an aliquot was taken for PGE? and TX& determinations byzysing a radioimmunoassay procedure (PGEzI RIA KIT, New England Nuclear and TXBZ-‘~“I RIA KIT, New England Nuclear). Statistical analysis
Statistical significance of differences was determined by two tailed “t” test for independent populations. When multiple comparisons were necessary Student-Newman-Keuls test was used after analysis of variance. Results PGE2 and TXB2 release by immunized normal T cells
and
As shown in Figure 1 non-immunized and alloimmunized T cells are able to generate PGE2 and TXB*. However, the productions of PGEz and TXB;! were significantly higher in alloimmune T
Preparation of supernatants
Cell free supernatants were obtained by incubation of 4 x lo7 T lymphocyte enriched cells alone or with 0.6-1.2 mg of lymphoid organ alloextracts in 1 ml of RPMI-1640 for 30 min at 37” followed by centrifugation of the cell mixture for 15 min at 500 g. Alloextracts were obtained according to the method described by Braun et al. (11). Briefly, lymphatic organs were homogenized in phosphate buffer saline (PBS) and sonicated for 10 min at 10 kc/set, lipids were extracted with chloroform and the aqueous phase recovered and centrifuged at 20.000 g for 30 min.
TXE2
PGEZ
TX&
PGE,
Fig. 1 Basal prostanoid synthesis by non-immunized (0) and immunized (m) T cells. PGE, and TXB, amounts were determined in cells (A) and in their supernatants (B) after incubation for 30 minutes at 37°C according to the experimental procedures described in Methods.
ALLOGENIC STIMULUS INDUCES PC AND THROMBOXANE PRODUCTION
205
(H-2b) alloextracts. These results show that the alloextracts must share the same H-2 specificity as the immunizing strain in order to induce T cell cyclooxygenase enzyme hyperactivity. Discussion
PGEz
1x02
PGE2
TX62
Fig. 2 PGEr and TXB, synthesis by non-immunized (0) and immunuzed (m) T-cells after exposure to specific alloantigen. Prostanoid amounts were determined in cells (A) and in their supematants (B) after incubation in the presence of alloextracts as described in the Methods.
lymphocytes than in non-immunized T cells. Balb/c anti-C&I T cells incubated with the specific C@ alloextracts produced significantly greater amounts of PGE;! and TXB:! than immune cells alone (Figure 2). Alloextracts did not modify significantly the production of PGE? or TXB2 in normal T cells (Fig. 2). Spec$city of PGE2 and TXBZ production alloimmune lymphocytes
by T
To analyze the participation of products of the Major Histocompatibility Complex (MHC) in the phenomenon, T immune cells from BALB/c mice with BALB/c anti C3H (H-2k) specificity were exposed to alloantigens from different strains. As shown in the Table we obtained an increased production of PGE2 and TXB2 with both C3H (H-2k) and AKR (H-2k) alloextracts. On the contrary, increased production of prostanoids was not obtained with BALB/c (H-2d) or C57 Bl/Hep Table
Specificity
of PGE,
and TXB, production
of
T lymphocytes Supernatans of
PGF,
TXBz (Pdb4
T T T T T
cell cell cell cell cell
alone + AlloAg C,H + AlloAg AKR + C.57 Bl/Hep + BALB/c
2.3 8.5 9.3 2.1 2.4
+ + f f 5
0.1 0.9 1.1 0.2 0.1
5.6 27.4 31.1 4.9 5.3
+ 1.0 rfI 1.2 + 1.8 f 0.9 f 1.0
Balb/c anti C,H alloimmune T cells were incubated alone or in the presence of alloextracts obtained from different strains (AlloAg). Values represent the Mean f S.E.M. of 5 separate experiments.
In this study we have shown that T lymphocytes from alloimmunized mice are able to produce higher amounts of PGE2 and TXB* than normal active T cells. This points to a more cyclooxygenase enzyme in alloimmune T lymphocytes than in normal T cells, which is responsible for the synthesis and release of PGE2 and TXB,?. Our data also show that immune T cells in the presence of specific alloantigens are abIe to synthesize and release both cyclooxygenase derived arachidonic acid products in higher amounts than T immune cells not challenged with the specific antigen. ‘The ability of lymphocytes to synthesize PGE? or TXA2 has been previously reported (7, 13, 14). The response of T cells to antigen involves a cascade of cellular events which culminates in T cell proliferation. Activation of T receptors by the specific antigen involves an increase of free cytoplasmic Ca++ concentration (15). Because changes in intracellular levels of Ca++ or Ca++ fluxes result in modifications of phospholipase activity and arachidonic acid metabolism it is tempting to speculate that stimulation of T cell receptor or associated proteins is followed by changes in arachidonic acid metabolism and prostanoid synthesis. The increased prostanoid synthesis only takes place when immune T cells are antigenically challenged with the same H-2 specificities as used for immunization. In order to obtain PGE;! or TX& products from active T cells, alloextracts must derive from H-2 compatible strains (AKR and CjH, both H-29. When alloantigens are derived from H-2 incompatible strains (BALB/c, H-2d or C57 Bl/Hep, H-2b) the production of PGEz and TXBz tends to be lower. In short, the data indicate that T cells sensitized against MHC products are able to release PGE? and TXB, during the specific recognition of a product of either the MHC or of a very closely linked gene. The bulk of evidence suggests that prostaglandins play a key role in the regulation of both humoral and cell-mediated immunity. Usually PGE acts as a feedback inhibitor of the response (13). Perhaps, the synthesis and release of PGE2 during alloantigenic recognition represent a feed-
206
PROSTAGLANDINS
back mechanism capable of regulating the response . On the other hand, the effect of TXA2 on lymphocyte function is difficult to determine because it is very labile product which is rapidly convet-ted to TXB,. Available data upon the action of TXA;! on the immune response-are contradictory and its role is still largely unknown (17, 18, 19). Experiments presented in the proceeding section as well as data published previously (2, 16) suggest that PGE2 and probably TXA;! may play some role in the alloimmune response. Further experiments are necessary to stablish the exact function of prostanoids in the alloimmune response. Acknowledgements The present study has been 3904802/85 from CONICET.
supported
by Grant.
PID
References 1. Genaro, A. M., Borda, E. S., Cremaschi, G. A., SterinBorda, L. and Braun, M. H-2 specific inotropic effect of alloimmune lymphoid cells on mouse isolated atria. Immunopharmacology 11: 129-140,1986. 2. Borda, E. S., Genaro, A. M., Peredo, H, Cremaschi, G. A., Perez-Leiros, C. and Sterin-Borda, L. Alloimmunization induced changes in thymocytes prostaglandin levels: a signal for the induction of biological activity. Int. J. Immunopharmacol. 7: 647-653, 1985. Goodwin, J. S. and Cluppens, J. Regulation of the immune response by prostaglandins. J. Clin. Immunol. 3: 295-315, 1983. Goldyne, M. E. and Stobo, J. D. Immunoregulatory role of prostaglandins and related lipids. Crit. Rev. Immunol. 2: 189-223, 1981. Humes, J. L., Salcowski, S. and Galavage, M. Evidence for two sources of arachidonic acid for oxidative metabolism by mouse peritoneal macrophages. J. Biol. Chem. 257: 1591-1594.1982. Lewis, G. P. Immunoregulatory activity of metabolites of AA and their role in inflammation. Br. Med. Bull. 39: 234-245. 1983.
7.
LEUKOTRIENES
AND ESSENTIAL FATTY ACIDS
Rinaldi-Garaci, C., Garaci, E. and Del Gabbo. U. Modulation of endogenous prostaglandins by thymosinalpha lymphocytes. Cell Immunol. 80: 57-63. 1983. 8. Braun, M., Saal, F., Pasqualini, C. D. Aspectos inmunologicos del crecimiento tumoral murino alogenico. Sangre (Barcelona) 19: 153-156. 1974. 9. Julius, M. H., Simpson, E. and Herzenberg, L. A. A rapid method for the isolation of functional thymusderive murine lymphocytes. Eur. J. Immunol. 3: 645-649, 1973. 10. Braun, M., Sen, L. Bachman, A. E. and pavlosky, A. Cell migration inhibition in human lymphomas -using lvmnh node and cell line extracts. Blood 39: 368-376, i97i. rr, Friilich, J. C., Wilson, T. W.. Sweetman. B. J.. Smigel. M., Mies, A. S. Can, K., Watson, J. T. and Oates, J. A. Urinary prostaglandins. Identification and origin. J. Clin. Invest. 55: 763-77?, 1975. 12. Parker. C. W., Stersone, W. F., Huler, M. G. and Kelly, J. P. Formation of TXB2 an hydroxyarachidonic acids in purified human lymphocytes in the presence and absence of PHA. J. Immunol. 222: 1572-1578, 1979. 13. Bauminger, S. Differences in prostaglandin formation Prostaglandins between thymocytes subpopulations. 16: 351-355,1978. 14. Aussel, C., Didier, M. and Fehlmann, M. Prostaglandin synthesis in human T cells. Its partial inhibition by lectius and anti-CD, anti bodies as a possible step in T cell activation, J. Immunol. 138: 3094-3099, 1987. 15. Inboden, J. B., Weiss, A. and Stobo, J. D. The antigen receptor an human T cell line initiates activation by incytoplasmic free calcium. J. Immunol. creasing 134: 663-668, 1985. 16. Borda, E. S., Genaro, A. M., Perez Leiros, C., Cremaschi, G., Peredo, H. and Sterin-Borda, L. Prostaglandin CAMP production and biological activity of alloimmune thymocytes. Prost. Leuk. Med. 19: 197-208, 1985. 17. Kedly, J. P., Johnson, M. C. and Parker, C. W. Effect of inhibitions of arachidonic acid metabolism on mitogenesis in human lymphocytes: possible role of thromboxanes and products of the liboxygenase pathway. J. Immunol. 122: 1563-1571, 1979. 18. Gordon, D., Noreni, A. M. E. and Thomas, R. V. Selective inhibition of thromboxane biosynthesis in human blood mononuclear cells and the effects on mitogenstimulated lymphocyte proliferation. Br. J. Pharmacol. 74: 469-475, 1981. 19 Ceuppens, J. L., Vertessen, S. Deckmyn, H. and Vermylen, J. Effects of thromboxane A2 on lymphocyte proliferation. Cell Immunol. 90: 458-463, 1985.