Increased growth of RSV-induced tumors in chickens partially tolerant to MHC alloantigens

Chickens withB²B² MHC genotypes were made partially tolerant to B₅ MHC cell-surface antigens and the fate of their Rous-sarcoma-virus (RSV)-induced tumors was determined.B²B² chickens partially tolerant to viable or lysed white blood cells (WBC) or viable red blood cells (RBC) fromB⁵B⁵ chickens had a significantly higher incidence of tumor progression than untreated, PBS-treated, orB²B² chickens inoculated with WBC from otherB²B² chickens. The criteria for tolerance were absence of antibody titer to the cell type inoculated and acceptance of allografts fromB⁵B⁵ donors byB²B² chickens. Graft-vs-host reactions occurred only inB²B² chickens inoculated with viable WBC fromB⁵B⁵ chickens. It appears thatB²B² chickens partially tolerant to B₅ antigens failed to mount a successful immune response to RSV-induced tumors partly because a B₅ MHC antigen(s) cross-reacted with a tumor associated antigen(s) thereby severely limitingB²B² host recognition of the tumor as foreign. Since WBC and RBC cell-surface antigens appear to contribute similarly to the effect, theB-F- region of the MHC may be involved.