Enhancement of chicken hemagglutinin response by thymocytes.

Antigen responsive cells, detectable with the cell transfer antibody assay, are abundant in the blood and spleen of chickens after immunization. In experiments where serial dilutions of donor immunocyte-antigen mixture were cultured in host embryos, each two-fold dilution of the mixture resulted in approximately a four-fold reduction in hemagglutinin output. When higher than normal concentrations of donor buffy coat were used, however, serial dilutions resulted in antibody output that was more directly proportional. The overall dose-response curve of relative donor cell number to antibody production appears to be biphasic, with a slope of a first order reaction at higher concentrations, and a steeper slope at lower concentrations of donor cells. The hemagglutinin response in the adoptive cell transfer system was enhanced when autologous thymocytes were added to the immunocyte-antigen mixture. Data from the kinetic and thymocyte supplement experiments taken together strongly indicate that the mouse erythrocyte antigen responsive cells of the chicken, like their mammalian counterpart the antigen-reactive units, involve the cooperation of T and B type lymphocytes.