Canine transmissible venereal tumor cell depletion of B lymphocytes: molecule(s) specifically toxic for B cells.
Canine transmissible venereal tumor (CTVT) is an excellent model for investigating the interaction between host immunity and tumor growth. Although CTVT is an allograft, initially the host immune system is unable to destroy the tumor cells, and the tumor grows progressively for about 4-6 months (P phase). After a short stable phase, the tumor undergoes regression (R phase). In this study, CTVT inoculation significantly reduced the proportion of B lymphocytes among all peripheral blood lymphocytes (PBL), but the proportion of B lymphocytes returned to normal after complete removal of CTVT. Following CTVT inoculation, immunoglobulin concentrations decreased gradually, coincident with B lymphocyte decline. Furthermore, CTVT secreted a soluble, heat- and protease K-sensitive cytotoxic molecule(s) that destroyed peripheral blood B lymphocytes (PBBL) but spared other types of immune cells regardless of whether mitogens, such as IL-2 or Con A, were present. The decrease in the proportion and viability of PBBL was caused by a cytotoxic molecule(s) that induced apoptosis. The molecular weight of the CTVT-derived cytotoxic molecule(s) was 30-100kDa. Human, domestic cat, horse and mouse B cells were also sensitive to the substance.
Liao
Kuang-Wen
KW
Department of Veterinary Medicine, National Taiwan University, 142 Chou-San Road, Taipei, 106, Taiwan, ROC.
Hung
Shao-Wen
SW
Hsiao
Ya-Wen
YW
Bennett
Michael
M
Chu
Rea-Min
RM
D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000473:pathology; D003208:Concanavalin A; D003601:Cytotoxicity Tests, Immunologic / Q000662:veterinary; D004283:Dog Diseases / Q000276:immunology* / Q000473:pathology; D004285:Dogs; D019286:Endopeptidase K / Q000276:immunology; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D015151:Immunoblotting / Q000662:veterinary; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D007376:Interleukin-2 / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008297:Male; D014685:Venereal Tumors, Veterinary / Q000276:immunology* / Q000473:pathology
D007376:Interleukin-2; D003208:Concanavalin A; D019286:Endopeptidase K