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Interaction of mistletoe lectin I with Kupffer cells and endothelial cells of mouse liver
Acta histochem. 78, 123-129 (1986) VEB Gustav Fischer Verlag Jena
Staatliches Institut fUr Immunpriiparate und Nahrmedien1 ), Berlin, DDR Department of Virology, Faculty of Medicine 2 ), Strasbourg, France
Interaction of mistletoe lectin I with Kupffer cells and endothelial cells of mouse liver
With 2 Figures (Received .January 10, 1985)
Summary The i1l vitro-formation of blebs by en
Introduction Toxic plant lectins as ricin, ahrin, and mistletoe lectin I (ML I) consist of 2 different chains. The A chain prohahly hy enzymatic activity inhihits the protein synthesis on riboRomal level and the B chain hinds to galactose containing glycoconjugates on the cell surface. These leetinR are of increasing interest in cancer therapy. Isolated A chains are taken for preparation of iml1mnotoxins and the native lectins are even used directly hecause they seem to have a higher affinity for some kinds of tumour cells than for "normal" cells. Thus, the antitUlIlor preparations h\cador® and Helixor® contain different amounts of ML I (ZISKA and FRANZ 1985). Recently ricin was also given in a phase I study to 54 cancer patients (FODSTA])T et al. 1984). Of course, one must take into account the well known toxicity of these lectins, toxicity which mayor may not be connected to the inhibition of protein synthesis. FLEXNER (1897) already descrihed necrosis in liver and other organs after ricin treatment of animalR. DERENZINI et al. (1976) found that primarely sinusoidal liver cells were progressively damaged by ricin until the cells became necrotic. SKILLETER et al. (1981) reported that nonparenchymal cells from rat liver accumulate 125J-lahelled ricin in vivo to a much greater extent than parenchymal cells. It can be assumed that Kupffer cells playa key role in the reaction of the organism to parenterally administered toxic lectins. The aim of this work is to incrcaRe our understanding of the interaction of ML I with nonparenchymal liver cells. Therefore, morphological alterations of Kupffer cells and endothelial cells of mouse liver after ML I treatment in vitro were investigated by scanning electron microscopy.
Materials and methods Isolation oj Kupjjer and endothelial cells: Mice from A/.J strain, weighing 25 g were killed by cervical dislocation. The liver was perfused in situ with Carr-deprived medium containing 0.05 % g*
124
H.
FRANZ,
A.·lI1.
S T EE'FAN
anrl A.
KIRN
Fig. 1. Kupffer cells. a. norm al Kupffer cell in vitro without any treatment. X 2,500. b. Kupffer cell after trea tment with ML I (lO,ug/ ml) for 7 h. Multiple blebs are formed. X 5,000. Beside the blebs also fil a ments are vis ible. X 5,000.
c.
Interaction of mistletoe lectin I
125
collagenase (Worthington t ype 1, CLS) at a flow r a te of 5 ml per min for 30 s. Liver tissue~ was then gently disrupted with scissors and pinces and incub ated in a collagenase solution (0.05 % in GEY'S Bala nced Salt so lution : GBS) in a girotory water bath shaker (New.Brunswick) at 280 rjmin for a period of 3n to 45 min. This incubation leads to a mechanica l lysis of hepatocytes. After filtr at ion on nylon, centrifugation at 300 g, the pellet was suspended in a metrizamide solution (Ny egaord Oslo) . The fin al dens ity of t h e suspension is adjusted to 1.089 g jcm 3 • After a centrifugation at 1,4()0 g for 15 min, si nusoid a l cells form a band on t h e top o f the tube . These cells are co ll ec t ecl ancl washed once w it h G HS . K upffer and endothelial ce lls a re separated by centrifugal e lu tr ia tion. A 1st elutriation, at a rotor speed of 2,500 r jmin a llows one to obt ain 3 fraction s. Fr'({ction I elutecl at H flow rate of 22 mljlllin contains endotheli a l cells and debris. Fraction I I at a flow rate of 32 Illl j lllin is a m ix ture of Kupffer a nd endothelia l cells which display the s a m e dyrHunic equili bri ulll . This fr act ion is discared . l'm.ction III obtained at 44.5 m ljm in corres ponds to Kupffer cells. Fraction I is purified in a 2nd elut riation at a rotor speed of 3,400 r jlll in. Debris are elu ted at 31 ml jlllin and endothe lia l cells at 61 ml j min. Cells are grown on round glass slids (12 mm) in Linbro 24 well p lats for 24 h in Dulbecco's mod ified Eagle mediu m (20 mmo!j! Hepes ancll0 mmoljl NaHCO a ) supplemented with 20 % fetal calf serum. This tech· nique h as a lready been d escribed (KIRX et a l. 1980; STEFFAN et a l. 1981; KIRK et al. 1982). Scanning electron m icroscopy: Cells were fixed with 2.5 % glutaraldehyde in cacodylate buffer (0.075 mlTiol jl, 4.5 % sucrose, 1 Jl1ll1ol jl :\-IgC! ~, and 1 mmol jJ CaCI2 , pH = 7.4) for 24 h, postfixed with 1 % OS04 in water, d ehydrated with ethanol, critical point dried , gold sp utter ed a nd ob· served in a Ph-iii!'", EM 300. Preparation of mistletoe lectin I: ~IL I was prepared as described earlier (ZISKA et al. 1978).
Results and Discussion As shown in Fig. 1 Kupffer cells as well as endothelial cells (Fig. 2) of mouse liver develop numerous protrusions (blebs) aft er incubation with ML I solution (10 f-tg/ml for 7 h). The alterations are localized exclusively in the central part of the cells while the dam aged cells rem ain still anchored on the support by num erous clearly visible
126
H.
F RANZ ,
A.·M.
S T E FF AN
an d A.
KIRN
Fig . 2. Endothelial c ells. (I. norm al endotheli al cell fro m mo use liver. The sieve plates are clearly visible. x 5,000. b. Blebs formation after 7 h by treatment which ML I (IO !~g ML I /m l). Note the fil amentous structures . x 5,000. c. In so me endo t heli al cells even after ML I·trea tment (7 h, 10 ftg/m l) r esid ues of sieve pla t es a re sho wn. X 5,000.
Interaction of mistletoe lectin I
127
(Fig 1) filaments. The characteristic fenestrations (sieve plates) of endothelial cells (Fig. 2) are partially preserved (Fig. 2). The extent of the alteration of the sinusoidal liver cells indicates an irreversible degeneration. After in cubation for 1 h (concentration 10 flg ML I/ml) and at concentrations of 1 flg ML Ilml (7 h), we did not find signifi cant cell modifications. The described alterations have been found only in 30 % of the Kupffer cclls and 25 % of endothelial cells treated under the same conditions. The formation of cell mem brane protrusions by the toxic lectins ricin and ML I has been studied before mainly on tumour cells. CREPPY et al. (1981) reported protrusions induced by ricin (5 pmollml corresponding to 325 ng/ml) on Hepatoma Tissue Culture cells (HTC) aft er 8 to 12 h. Isolated rat hepatocytes needed much higher lon centrations (750 pmol/ml corresponding to 49 flg/ml) to develop these blebs. This effect occured only on 10 to 20% of the hepatocytes. We observed earlier (BERGMA:NK et a!. 1984) blebs formation of EHRLICH ascites tumour cells (EAT) after 1 h incll hation Ilsing concentrations from 1 to 10 flg ML I/ml per 107 cells. It is nece~"ary to mention that membranes of the altered cells are impermeable by Trypan hllle. H,ihereau-Gayon found blebs formation on HTC cells after in cubation witb WI L I and Iscador® (pers. com munication). A prereq llisite for all t hese membrane alterations is no doubt thc binding of the toxic lettins to distinct structures on cell membranes according to PAt:L EHRLICH' S postulftt,e "Corpora. non agunt nisi fixata" (substances do not react without fixation). Wherea.~ one ('an aSSIIIlIe that ricin and ML I are bound normally via their B chain to galact,ose ('ontaining glycoconjugates on the cell surface, the mechanism of their interact,ion with Kllpffcr ('clls and endothelial cells fleems to be more complicated. Different type" of rea('tions IllUst be discussed:
128
H. FRANZ, A.-M. STEFFAN and A. KIRN
1. The "typical" reaction of toxic lectins involves the following steps:
a) binding to galactose containing glycoconjugates, b) penetration of the cell membrane by the A chain, c) inhibition of protein synthesis. It is possible, that the membrane lesions are "due to the inhibition of the synthesis of a protein essential for the cytoskeleton to function and control the membrane shape" (CREPPY et al. 1981). This type of reaction needs the complete lectin. Neither A or B chain alone can react in this way as has been shown by CREPPY et al. (1981) for ricin and by BERGMANN et al. (1984) for ML 1. Because a great number of cells (not only tumour cells!) bear galactose containing glycoconjugates on their membrane this mechanism cannot by excluded for Kupffer and endothelial cells. 2. In relation to their phagocytic activity, Kupffer cells have a special ability for carbohydrate recognition which is different from the binding capacity of hepatocytes. They have an affinity for galactose-terminated derivates (asialoglycoproteins) [review: JONES and SUMMERFIELD (1982)J. Kupffer cells and endothelial cells carry a surface lectin which is specific for N-acetylglucosamine and/or mannose. Such a mannan binding protein has been isolated from rabbit liver (KOWASAKI et al. 1978). In agreement to these findings, SKILLETER et al. (1981) reported that rat nonparenchymal liver cells in vivo accumulate 125.J -labelled ricin to a much greater extent than hepatocytes. This uptake is not essentially inhibited by galactose suggesting that the ricin uptake by Kupffer cells is due to its mannose residues. ML I also contains mannose as has been demonstrated by precipitation of the A chain as well as the B chain by Con A. Therefore it could be assumed that the remarkable morphological alterations shown in this paper are the result of ML I uptake by mannose specific surface lectins. Studies about the interaction of the isolated A chain of ML I with Kupffer cells and endothelial cells are in progress. Recently we demonstrated that the A chain alone can act as a mitogen for lymphocytes [review: FRANZ (1985)J. In conclusion, the results demonstrate that the uptake of toxic lectins by Kupffer cells and endothelial cells can be accompagnied by morphological alterations and cell lesions. ML I seems to be less toxic than ricin which produces under the same conditions as used for ML I protrusions on 100 % of Kupffer cells and endothelial cells (CREPPY et al. 1981). The ML I concentration used in this work was much higher than used in tumour therapy. Nevertheless the liver function after injection of ricin or ML I into patients should be continously controlled. The described affinity of Kupffer cells and endothelial cells can also be the reason for a very fast elimination of therapeutically administered ricin or ML 1. To avoid such bindings the preparation of a whether mannose-free or chemically modified mannose-containing lectin would be necessary. On the other hand, it can be possible that small doses of ML I increase the phagocytic activity of Kupffer cells. Recently we have shown [review: FRANZ (1985)J that rat peritoneal macrophages are activated by ML 1.
References BERGMANN, P., ZISKA, P., und FRANZ, R., Morphologie von Ehrlich-Miiuse-Ascites-Tumorzellen nach Einwirkung des cytotoxischen Lektins I der Miste!. 11. Tagung "Elektronenmikroskopie", 16.-18.1.1984, Dresden, in press. CREPPY, E. E., LUGXIER, A.-A., .J., BECK, G., DIRHEIMER, G., PETZIXGER, E., and FRIMMER, M., Comparative studies by scanning electron microscopy On the effect of ricin on the cell membrane of hepatoma cells and isolated hepatocytes. Toxico!. Europ. Res. 3, 179-185 (1981).
Interaction of mistletoe lectin I
129
DEREXZIXI, M., BOXETTI, E., :\L"RIXOZZI, V., and ~TIRPE, F., Toxic effects of ricin. Studies on the liver lesions. Virchows Arch. B. Cell Path. 20, 15-18 (1976). FLEXNER, ~., The histological changes prollncell by ricin and abrin intoxications. J. expo Med. 2, 197-216 (1897). FODsTADT, 0., KVALHEIM, G., GODOL, A., LOTSBERG, .J., AA~IDAL, S., HOST, H., and PIHL, A., Phase I study of the plant protein ricin. Cancer Res. 44, 862-865 (1984). FRANZ, H., Inhaltsstoffe del' i\1istel (T'iscum ([lbum L.) als potentielle Arzneistoffe. Pharmazie 40, 97-104 (1985). JONES, E. A., and SUMMERFIELD, ,J. A., Kupffer cells in the liver. Biology and Pathology (ed. by .J. ARIAS, H. POPPER, D. SCHACHTER and D. A. ~HAFRITZ). Raven, New York 1982, pp. 507 to 523. KAWASAKI, T., ETCH, R., anll YA~IASIIIXA, 1., Isolation and characterisation of a mannan-binding protein from rabbit liver. Biochem. Biophys. Res. Commnn. 81, 1018-1024 (1978). KELLER, F., and CIXQUALBRE, .T., Endocytic capacities of Kupffer cells isolated from the human adult liver. Hepatology 2,216-222 (1982). KIRN, A., STEFFAN, A. M., BINGEN, A., CINQUALBRE, J., et GENDRAULT, T., Isolement et culture de cellules de Kupffer humaines. C.R. Acad. ~ci. (Paris) ~er. D, 291, 249 (1980). SKILLETER, D. N., l' AIXE, A .•J., and ~TIRPE, F., A comparison of the accumulation of ricin by hepatic parenchymal and nonparenchymal cells and its inhibition of protein synthesis, Biochim. Biophys. Acta 677,495-500 (1981). STE}'FAN, A. M., LECERF, F., KELLER, F., CINQI-ALBRE, J., et KIRN, A., Isolement et culture de cellules endoth61iales de foies hUlllclin et murin. C.R. Acad. Sci. Paris, (Ser. III) 292, 809-815 (1981). ZISKA, 1'., and FRANZ, H., Determination of lectin contents in commercial mistletoe preparations for cancer therapy using the ELItlA technique. Lectins, Biology, Biochemistry, Clinical Biochemistry. (Eds.: BOG-HANSEN, T. C., ,J. BREBOROWICZ). Vol. 4, W. de Gruyter, Berlin (West) 1985, pp. 47:3-480. and KIXDT, A., The lectin from Viscum album L. Purification by biospecific affinity chromatography Experientia 34, 123-124 (1978). Author's address: OMR Prof. Dr. Dr. H. FRAXZ, Staatliches Institut fiir Immunpriiparate und Niihrmedien, DDR - 1120 Berlin, Klement-Gottwald-Allee 317-321.
Staatliches Institut fUr Immunpriiparate und Nahrmedien1 ), Berlin, DDR Department of Virology, Faculty of Medicine 2 ), Strasbourg, France
Interaction of mistletoe lectin I with Kupffer cells and endothelial cells of mouse liver
With 2 Figures (Received .January 10, 1985)
Summary The i1l vitro-formation of blebs by en
Introduction Toxic plant lectins as ricin, ahrin, and mistletoe lectin I (ML I) consist of 2 different chains. The A chain prohahly hy enzymatic activity inhihits the protein synthesis on riboRomal level and the B chain hinds to galactose containing glycoconjugates on the cell surface. These leetinR are of increasing interest in cancer therapy. Isolated A chains are taken for preparation of iml1mnotoxins and the native lectins are even used directly hecause they seem to have a higher affinity for some kinds of tumour cells than for "normal" cells. Thus, the antitUlIlor preparations h\cador® and Helixor® contain different amounts of ML I (ZISKA and FRANZ 1985). Recently ricin was also given in a phase I study to 54 cancer patients (FODSTA])T et al. 1984). Of course, one must take into account the well known toxicity of these lectins, toxicity which mayor may not be connected to the inhibition of protein synthesis. FLEXNER (1897) already descrihed necrosis in liver and other organs after ricin treatment of animalR. DERENZINI et al. (1976) found that primarely sinusoidal liver cells were progressively damaged by ricin until the cells became necrotic. SKILLETER et al. (1981) reported that nonparenchymal cells from rat liver accumulate 125J-lahelled ricin in vivo to a much greater extent than parenchymal cells. It can be assumed that Kupffer cells playa key role in the reaction of the organism to parenterally administered toxic lectins. The aim of this work is to incrcaRe our understanding of the interaction of ML I with nonparenchymal liver cells. Therefore, morphological alterations of Kupffer cells and endothelial cells of mouse liver after ML I treatment in vitro were investigated by scanning electron microscopy.
Materials and methods Isolation oj Kupjjer and endothelial cells: Mice from A/.J strain, weighing 25 g were killed by cervical dislocation. The liver was perfused in situ with Carr-deprived medium containing 0.05 % g*
124
H.
FRANZ,
A.·lI1.
S T EE'FAN
anrl A.
KIRN
Fig. 1. Kupffer cells. a. norm al Kupffer cell in vitro without any treatment. X 2,500. b. Kupffer cell after trea tment with ML I (lO,ug/ ml) for 7 h. Multiple blebs are formed. X 5,000. Beside the blebs also fil a ments are vis ible. X 5,000.
c.
Interaction of mistletoe lectin I
125
collagenase (Worthington t ype 1, CLS) at a flow r a te of 5 ml per min for 30 s. Liver tissue~ was then gently disrupted with scissors and pinces and incub ated in a collagenase solution (0.05 % in GEY'S Bala nced Salt so lution : GBS) in a girotory water bath shaker (New.Brunswick) at 280 rjmin for a period of 3n to 45 min. This incubation leads to a mechanica l lysis of hepatocytes. After filtr at ion on nylon, centrifugation at 300 g, the pellet was suspended in a metrizamide solution (Ny egaord Oslo) . The fin al dens ity of t h e suspension is adjusted to 1.089 g jcm 3 • After a centrifugation at 1,4()0 g for 15 min, si nusoid a l cells form a band on t h e top o f the tube . These cells are co ll ec t ecl ancl washed once w it h G HS . K upffer and endothelial ce lls a re separated by centrifugal e lu tr ia tion. A 1st elutriation, at a rotor speed of 2,500 r jmin a llows one to obt ain 3 fraction s. Fr'({ction I elutecl at H flow rate of 22 mljlllin contains endotheli a l cells and debris. Fraction I I at a flow rate of 32 Illl j lllin is a m ix ture of Kupffer a nd endothelia l cells which display the s a m e dyrHunic equili bri ulll . This fr act ion is discared . l'm.ction III obtained at 44.5 m ljm in corres ponds to Kupffer cells. Fraction I is purified in a 2nd elut riation at a rotor speed of 3,400 r jlll in. Debris are elu ted at 31 ml jlllin and endothe lia l cells at 61 ml j min. Cells are grown on round glass slids (12 mm) in Linbro 24 well p lats for 24 h in Dulbecco's mod ified Eagle mediu m (20 mmo!j! Hepes ancll0 mmoljl NaHCO a ) supplemented with 20 % fetal calf serum. This tech· nique h as a lready been d escribed (KIRX et a l. 1980; STEFFAN et a l. 1981; KIRK et al. 1982). Scanning electron m icroscopy: Cells were fixed with 2.5 % glutaraldehyde in cacodylate buffer (0.075 mlTiol jl, 4.5 % sucrose, 1 Jl1ll1ol jl :\-IgC! ~, and 1 mmol jJ CaCI2 , pH = 7.4) for 24 h, postfixed with 1 % OS04 in water, d ehydrated with ethanol, critical point dried , gold sp utter ed a nd ob· served in a Ph-iii!'", EM 300. Preparation of mistletoe lectin I: ~IL I was prepared as described earlier (ZISKA et al. 1978).
Results and Discussion As shown in Fig. 1 Kupffer cells as well as endothelial cells (Fig. 2) of mouse liver develop numerous protrusions (blebs) aft er incubation with ML I solution (10 f-tg/ml for 7 h). The alterations are localized exclusively in the central part of the cells while the dam aged cells rem ain still anchored on the support by num erous clearly visible
126
H.
F RANZ ,
A.·M.
S T E FF AN
an d A.
KIRN
Fig . 2. Endothelial c ells. (I. norm al endotheli al cell fro m mo use liver. The sieve plates are clearly visible. x 5,000. b. Blebs formation after 7 h by treatment which ML I (IO !~g ML I /m l). Note the fil amentous structures . x 5,000. c. In so me endo t heli al cells even after ML I·trea tment (7 h, 10 ftg/m l) r esid ues of sieve pla t es a re sho wn. X 5,000.
Interaction of mistletoe lectin I
127
(Fig 1) filaments. The characteristic fenestrations (sieve plates) of endothelial cells (Fig. 2) are partially preserved (Fig. 2). The extent of the alteration of the sinusoidal liver cells indicates an irreversible degeneration. After in cubation for 1 h (concentration 10 flg ML I/ml) and at concentrations of 1 flg ML Ilml (7 h), we did not find signifi cant cell modifications. The described alterations have been found only in 30 % of the Kupffer cclls and 25 % of endothelial cells treated under the same conditions. The formation of cell mem brane protrusions by the toxic lectins ricin and ML I has been studied before mainly on tumour cells. CREPPY et al. (1981) reported protrusions induced by ricin (5 pmollml corresponding to 325 ng/ml) on Hepatoma Tissue Culture cells (HTC) aft er 8 to 12 h. Isolated rat hepatocytes needed much higher lon centrations (750 pmol/ml corresponding to 49 flg/ml) to develop these blebs. This effect occured only on 10 to 20% of the hepatocytes. We observed earlier (BERGMA:NK et a!. 1984) blebs formation of EHRLICH ascites tumour cells (EAT) after 1 h incll hation Ilsing concentrations from 1 to 10 flg ML I/ml per 107 cells. It is nece~"ary to mention that membranes of the altered cells are impermeable by Trypan hllle. H,ihereau-Gayon found blebs formation on HTC cells after in cubation witb WI L I and Iscador® (pers. com munication). A prereq llisite for all t hese membrane alterations is no doubt thc binding of the toxic lettins to distinct structures on cell membranes according to PAt:L EHRLICH' S postulftt,e "Corpora. non agunt nisi fixata" (substances do not react without fixation). Wherea.~ one ('an aSSIIIlIe that ricin and ML I are bound normally via their B chain to galact,ose ('ontaining glycoconjugates on the cell surface, the mechanism of their interact,ion with Kllpffcr ('clls and endothelial cells fleems to be more complicated. Different type" of rea('tions IllUst be discussed:
128
H. FRANZ, A.-M. STEFFAN and A. KIRN
1. The "typical" reaction of toxic lectins involves the following steps:
a) binding to galactose containing glycoconjugates, b) penetration of the cell membrane by the A chain, c) inhibition of protein synthesis. It is possible, that the membrane lesions are "due to the inhibition of the synthesis of a protein essential for the cytoskeleton to function and control the membrane shape" (CREPPY et al. 1981). This type of reaction needs the complete lectin. Neither A or B chain alone can react in this way as has been shown by CREPPY et al. (1981) for ricin and by BERGMANN et al. (1984) for ML 1. Because a great number of cells (not only tumour cells!) bear galactose containing glycoconjugates on their membrane this mechanism cannot by excluded for Kupffer and endothelial cells. 2. In relation to their phagocytic activity, Kupffer cells have a special ability for carbohydrate recognition which is different from the binding capacity of hepatocytes. They have an affinity for galactose-terminated derivates (asialoglycoproteins) [review: JONES and SUMMERFIELD (1982)J. Kupffer cells and endothelial cells carry a surface lectin which is specific for N-acetylglucosamine and/or mannose. Such a mannan binding protein has been isolated from rabbit liver (KOWASAKI et al. 1978). In agreement to these findings, SKILLETER et al. (1981) reported that rat nonparenchymal liver cells in vivo accumulate 125.J -labelled ricin to a much greater extent than hepatocytes. This uptake is not essentially inhibited by galactose suggesting that the ricin uptake by Kupffer cells is due to its mannose residues. ML I also contains mannose as has been demonstrated by precipitation of the A chain as well as the B chain by Con A. Therefore it could be assumed that the remarkable morphological alterations shown in this paper are the result of ML I uptake by mannose specific surface lectins. Studies about the interaction of the isolated A chain of ML I with Kupffer cells and endothelial cells are in progress. Recently we demonstrated that the A chain alone can act as a mitogen for lymphocytes [review: FRANZ (1985)J. In conclusion, the results demonstrate that the uptake of toxic lectins by Kupffer cells and endothelial cells can be accompagnied by morphological alterations and cell lesions. ML I seems to be less toxic than ricin which produces under the same conditions as used for ML I protrusions on 100 % of Kupffer cells and endothelial cells (CREPPY et al. 1981). The ML I concentration used in this work was much higher than used in tumour therapy. Nevertheless the liver function after injection of ricin or ML I into patients should be continously controlled. The described affinity of Kupffer cells and endothelial cells can also be the reason for a very fast elimination of therapeutically administered ricin or ML 1. To avoid such bindings the preparation of a whether mannose-free or chemically modified mannose-containing lectin would be necessary. On the other hand, it can be possible that small doses of ML I increase the phagocytic activity of Kupffer cells. Recently we have shown [review: FRANZ (1985)J that rat peritoneal macrophages are activated by ML 1.
References BERGMANN, P., ZISKA, P., und FRANZ, R., Morphologie von Ehrlich-Miiuse-Ascites-Tumorzellen nach Einwirkung des cytotoxischen Lektins I der Miste!. 11. Tagung "Elektronenmikroskopie", 16.-18.1.1984, Dresden, in press. CREPPY, E. E., LUGXIER, A.-A., .J., BECK, G., DIRHEIMER, G., PETZIXGER, E., and FRIMMER, M., Comparative studies by scanning electron microscopy On the effect of ricin on the cell membrane of hepatoma cells and isolated hepatocytes. Toxico!. Europ. Res. 3, 179-185 (1981).
Interaction of mistletoe lectin I
129
DEREXZIXI, M., BOXETTI, E., :\L"RIXOZZI, V., and ~TIRPE, F., Toxic effects of ricin. Studies on the liver lesions. Virchows Arch. B. Cell Path. 20, 15-18 (1976). FLEXNER, ~., The histological changes prollncell by ricin and abrin intoxications. J. expo Med. 2, 197-216 (1897). FODsTADT, 0., KVALHEIM, G., GODOL, A., LOTSBERG, .J., AA~IDAL, S., HOST, H., and PIHL, A., Phase I study of the plant protein ricin. Cancer Res. 44, 862-865 (1984). FRANZ, H., Inhaltsstoffe del' i\1istel (T'iscum ([lbum L.) als potentielle Arzneistoffe. Pharmazie 40, 97-104 (1985). JONES, E. A., and SUMMERFIELD, ,J. A., Kupffer cells in the liver. Biology and Pathology (ed. by .J. ARIAS, H. POPPER, D. SCHACHTER and D. A. ~HAFRITZ). Raven, New York 1982, pp. 507 to 523. KAWASAKI, T., ETCH, R., anll YA~IASIIIXA, 1., Isolation and characterisation of a mannan-binding protein from rabbit liver. Biochem. Biophys. Res. Commnn. 81, 1018-1024 (1978). KELLER, F., and CIXQUALBRE, .T., Endocytic capacities of Kupffer cells isolated from the human adult liver. Hepatology 2,216-222 (1982). KIRN, A., STEFFAN, A. M., BINGEN, A., CINQUALBRE, J., et GENDRAULT, T., Isolement et culture de cellules de Kupffer humaines. C.R. Acad. ~ci. (Paris) ~er. D, 291, 249 (1980). SKILLETER, D. N., l' AIXE, A .•J., and ~TIRPE, F., A comparison of the accumulation of ricin by hepatic parenchymal and nonparenchymal cells and its inhibition of protein synthesis, Biochim. Biophys. Acta 677,495-500 (1981). STE}'FAN, A. M., LECERF, F., KELLER, F., CINQI-ALBRE, J., et KIRN, A., Isolement et culture de cellules endoth61iales de foies hUlllclin et murin. C.R. Acad. Sci. Paris, (Ser. III) 292, 809-815 (1981). ZISKA, 1'., and FRANZ, H., Determination of lectin contents in commercial mistletoe preparations for cancer therapy using the ELItlA technique. Lectins, Biology, Biochemistry, Clinical Biochemistry. (Eds.: BOG-HANSEN, T. C., ,J. BREBOROWICZ). Vol. 4, W. de Gruyter, Berlin (West) 1985, pp. 47:3-480. and KIXDT, A., The lectin from Viscum album L. Purification by biospecific affinity chromatography Experientia 34, 123-124 (1978). Author's address: OMR Prof. Dr. Dr. H. FRAXZ, Staatliches Institut fiir Immunpriiparate und Niihrmedien, DDR - 1120 Berlin, Klement-Gottwald-Allee 317-321.