ANTIBODY AND IMMUNOGLOBULIN PRODUCTION AT THE CELLULAR LEVEL IN BURSECTOMIZED-IRRADIATED CHICKENS

The effect of bursectomy combined with sublethal X-irradiation in the newly hatched chicken on the immunoglobulin and antibody producing capacity in later life was investigated. The previous findings of a significant incidence of hypogammaglobulinemia in such animals were confirmed. Spleen cells from severely hypogammaglobulinemic animals synthesized and secreted little or no immunoglobulin. Such spleen lymphoid cells contained fewer immunoglobulin antigenic determinants than spleen cells from irradiated control animals as evidenced by their relative inability to respond by an increased DNA synthesis after in vitro culture with rabbit antiserum to chicken immunoglobulin. Therefore, the deficiency in the immunoglobulin synthesis extends not only to actively secreting cells such as plasma cells, but to the entire lymphoid cell population. As expected, most irradiated-bursectomized chickens, irrespective of plasma immunoglobulin levels failed to produce detectable amount of circulating antibodies to Brucella abortus antigen in the primary immune response. Severely hypogammaglobulinemic animals were completely unable to elaborate any plaque forming cells (PFC) in the primary response to sheep red blood cells (SRBC). The results of this investigation support the contention that in the severely hypogammaglobulinemic bursectomized-irradiated chicken the entire antibody producing and immunoglobulin producing cell line is absent. The possibility remains that precursor or stem cells are present but are not appropriately directed to antibody synthesis by other cell types.