Transplantation of cells from bursa of Fabricius into surgically bursectomized chicks.

Abstract

Cells from bursa of Fabricius were transplanted intravenously into surgically bursectomized and bursectomized-irradiated chicks. The 61/2-week-old donors used were isogeneic with the recipients at the major histocompatibility locus. Survival pattern, gain of body weight, humoral immune responses, and microscopic morphology of spleen and cecal tonsils were studied to assess the effects of transplantation. Antigenic stimulation with SRBC and <i>Brucella abortus</i> was carried out at 28 and 35 days following the transplantation. The number of chickens producing natural and immune antibodies was approximately 2-fold greater in the transplanted groups than in untransplanted groups. Presence of germinal centers and plasma cells in the spleen and cecal tonsils paralleled the functional evidence for restoration of humoral immunity. These findings indicate that, at the time of a beginning involution of the bursa, the bursal stem cell is sufficiently mature to home to other lymphoid organs, and to proliferate and develop further without a bursal influence. This conclusion is supported by findings in chickens treated with cyclophosphamide in the newly hatched period. In these birds, transplantation of bursa cells resulted in a more frequent reconstitution of the bursa-dependent lymphoid system than occurred in the surgically bursectomized birds – even though no evidence of homing of transplanted cells to the bursa could be obtained.