Development of host plasma cells during graft-versus-host reactions in mice

Graft-versus-host (GVH) reactions induced by thymus or spleen cells in newborn mice were found to trigger the development of plasma cells in the medullary areas of lymph nodes. No germinal centers were found. The plasma cells were found from the fourth day of the GVH reactions and increased in numbers over the next few days. On the 14th day the plasma cells were still present, although in lower numbers. Results of immunodiffusion experiments indicated that during GVH reactions induced by spleen cells, donor as well as host plasma cells develop. In contrast, induction of GVH reactions by thymus cells leads to the development of plasma cells, which probably originate exclusively from the host. Positive Coombs' reactions were detected 15–20 days after induction of GVH reactions and host immunoglobulins were found to contribute to the Coombs' positivity. The GVH reactions stimulated the formation of antibodies to sheep erythrocytes. This effect was more marked on 7 S than on 19 S antibody production.