Function associated molecules on nonspecific cytotoxic cells: role in calcium signaling, redirected lysis, and modulation of cytotoxicity.
Monoclonal antibodies (mAbs) specific for a putative antigen receptor (function associated molecule, FAM) on fish NCC were tested for their ability to initiate signal transduction responses. Anti-FAM hybridoma target cells were significantly lysed by NCC when tested by redirected lysis (RL). Redirected lysis was enhanced by 1-h pretreatment of the NCC with anti-FAM mAb; however, 18-h pretreatment produced significant inhibition. The effects of the calcium ionophore A23187 on RL were also examined: 10(-4) M but not 10(-5) M A23187 significantly increased RL. Purified NCC were treated with mAb and cellular DNA synthesis was determined. Significant increases in NCC incorporation of tritiated thymidine were measured 72 h after treatment with mAb. Experiments were also conducted to determine levels of free cytosolic calcium in NCC following mAb binding. Anti-FAM mAb binding produced a rapid rise in cytosolic calcium (200-500 nM) determined by Fura-2/AM fluorescence. Calcium ionophore A23187, PHA, and Con-A treatment of NCC also produced significantly increased [Ca2+]i. Target cell binding by NCC caused a three-fold increase in [Ca2+]i. These data suggest that triggering of the FAM may initiate a signal(s) that activates cytotoxicity, increases cytosolic free calcium concentrations, and initiates DNA synthesis.
Evans
D L
DL
Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens 30602.
Harris
D T
DT
Jaso-Friedmann
L
L
D000818:Animals; D000911:Antibodies, Monoclonal; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002397:Catfishes; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000502:physiology*; D004247:DNA / Q000096:biosynthesis; D004306:Dose-Response Relationship, Immunologic; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology*; D010835:Phytohemagglutinins; D011946:Receptors, Antigen / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology*
D000911:Antibodies, Monoclonal; D010835:Phytohemagglutinins; D011946:Receptors, Antigen; D003208:Concanavalin A; D000001:Calcimycin; D004247:DNA; D002118:Calcium