Immune globulin production by the bursa of Fabricius of young chickens.

A study was made of the formation of immune globulins by lymphoid tissues from neonatal chicks. Incorporation of C-amino acid into γM and γG was demonstrated by means of radioimmunoelectrophoresis. Results were correlated with observations made on tissue sections stained for the presence of immune globulins with fluorescein-labelled antisera. The bursa of Fabricius synthesized γM as early as the 18th day of embryonic development, and was significantly more active than the spleen in the production of immune globulins during the 1st week after hatching. Medullary cells of the bursa follicles contained immune globulins. Synthesis of γM by the spleen became detectable on day 7. Comparable activities in immune globulin formation in bursa and spleen were obtained by day 15, while the spleen was much more active than the bursa in 3-month-old chickens. The thymus produced no γM but started to produce γG during the 2nd week after hatching. Bursa and spleen from 8-day-old germ-free chicks showed similar synthesis of γM, as did organs from normal animals. The significance of this early γM synthesis and its possible independence of antigenic stimulation are discussed.