title: Inhibition of concanavalin A response during osteopetrosis virus infection.
abstract: Infection of animals with oncogenic viruses frequently leads to an immunosuppressed state. We have examined immunosuppression induced by an avian osteopetrosis virus, myeloblastosis-associated virus of subgroup B inducing osteopetrosis [MAV-2(O)], and our results suggest that this virus induces immunosuppression by a novel mechanism. Lymphoid cells from osteopetrotic chickens did not respond to a wide dose range of concanavalin A (Con A) over a wide cell density range. Failure to undergo blastogenesis was not due to a lack of Con A-binding sites, since 125I-labeled Con A bound to lymphocytes from infected and uninfected chickens. Infected lymphocytes failed to respond to sodium metaperiodate stimulation, indicating that failure of blastogenesis was not due to a blockage of Con A receptor sites. MAV-2(O) infection of chicks 8 days of age resulted in a transient immunosuppression which appeared 1 to 2 weeks after infection. Cell-mixing experiments showed that MAV-2(O)-induced immunosuppression was not attributable to suppressor cells. In contrast, adherent cells from normal lymphoid preparations restored mitogenicity to lymphocytes from MAV-2(O)-infected animals. Adherent cells were present in the spleen and peripheral blood lymphocytes of MAV-2(O)-infected chickens in numbers comparable to those of the uninfected animal, and both sets of cells contained Fc-dependent phagocytic activity and nonspecific esterase. Peritoneal exudate cells were elicited from osteopetrotic and normal chickens in similar numbers. We conclude that MAV-2(O) induces immunosuppression by interfering with an accessory function of macrophage-like adherent cells.
mesh_terms: D000740:Anemia / Q000209:etiology; D000818:Animals; D001353:Avian Leukosis / Q000276:immunology*; D009189:Avian Myeloblastosis Virus; D002645:Chickens; D003208:Concanavalin A / Q000494:pharmacology*; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology*; D010022:Osteopetrosis / Q000209:etiology / Q000276:immunology*; D011952:Receptors, Concanavalin A / Q000378:metabolism; D012526:Satellite Viruses; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D011952:Receptors, Concanavalin A; D003208:Concanavalin A