Ontogeny of spontaneous antigen-binding cells in developing chick embryos.

Bursal and splenic lymphocytes in developing chick embryos were examined for the number of antigen binding cells (ABC) which could form rosettes with red blood cells from sheep, guinea-pig, rabbit or dinitrophenylated sheep red blood cells (DNP-SRBC). The kinetics of the development of bursal ABC to rabbit red blood cells (RRBC) did not vary significantly with age of embryo examined, and its frequency was constantly high. The number of cells which bind to SRBC, guinea-pig red blood cells (GPRBC) or DNP-SRBC was low in the bursa and increased in an approximately linear fashion with the age of embryo. With the exception of RRBC-ABC, similar results were obtained with splenic ABC. Furthermore, the frequencies of ABC were higher in the spleen than in the bursa. These events suggest the antigen-independent generation of clonal diversity during the developmental stage of chick embryos.