The proliferative capacity of the cells of the avian Harderian gland.

The largest concentration of plasmacytic cells within avian lymphomyeloid tissue appears in the Harderian Gland (HG). Mature plasma cells were the least frequent cell at day old and the most frequent by 5-weeks of age. Failure of phytohemagglutinin-M to stimulate blasting of HG cells may reflect the low number of T cells in the HG. On the other hand, the uptake of tritiated thymidine by HG cells after short term culture in complete medium was significantly greater than that of splenic cells. The proliferating cells were the plasmablast, and mature plasma cell. Our data demonstrated that labeled B-cells, administered intravenously to 2- or 6-week old syngeneic or allogeneic chickens, did not migrate to the HG. The origin of HG plasma cells may be B-cells which entered prior to 2 weeks of age or the HG may possess a special microenvironment which allowed stem cell differentiation. The maintenance of a high concentration of plasma cells in the HG in the presence of low levels of B-cells may reflect the long-lived nature of the resident B-cell and/or the inherent proliferative capacity of the HG plasmacytic cell.