ANTAGONISM BETWEEN DONOR AND HOST B CELLS IN ALLOTYPE CONGENIC CHICKEN CHIMERAS

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Abstract
B [bursa derived] cell chimaerism was analyzed in juvenile chickens given injections of major histocompatibility complex-compatible lymphoid cells. The allelic products of donor and host-derived B cells were monitored with antisera directed against immunoglobulin M1 (IgM) and G1 (IgG) isotype-specific allotypes. Injection of peripheral blood lymphocytes and spleen cells suppressed host allotype levels whereas purified T [thymus derived] lymphocytes were ineffective. Pretreatment of recipients with cyclophosphamide was more effective than irradiation in promoting engraftment and host B cell suppression. Host allotype suppression endured for several months after cell transfer and was attributable to B cell deletion, as ascertained by the lack of cells which expressed surface M1. In partially suppressed chickens, host G1 was inhibited to a greater degree than M1 allotype. Host recovery was followed by donor B cell rejection when low numbers of donor cells and/or inadequate host conditioning was used. Selective M1 chimaerism occurred when limiting numbers of spleen cells were transferred into cyclophosphamide-treated hosts, whereas selective G1 chimaerism resulted after the transfer of large numbers of peripheral blood lymphocytes or spleen cells into unconditioned recipients. These findings can be attributed to a B cell surveillance mechanism which may be similar to that postulated previously to explain resistance to hemopoietic and tumor cells.