The nature of active and passive thyroglobulin binding lymphoid cells in Obese strain (OS) chickens.

Thyroglobulin-binding lymphoid cells were identified in the spleen of Obese strain (DS) chickens by their capacity to form rosettes with thyroglobulin-coated chicken red blood cells. The nature of these cells was studied in inhibition experiments using turkey anti-chicken bursa or thymus cell sera and rabbit antisera specific for chicken Ig, gamma, mu, alpha, Fabgamma or Fcgamma. Spleen cells actively synthesizing surface receptors for thyroglobulin were identified as B cells and the receptors found to be complete IgM molecules. Normal T cells became thyroglobulin-rosette-forming cells via passive adsorption of thyroglobulin antibodies, a phenomenon which could be inhibited competitively by the addition of normal chicken serum to the incubation medium. Thyroglobulin antibodies passively adsorbed onto the surface of normal T cells also belong to the IgM class as verified both by inhibition experiments and studies employing IgM and IgG fractions of a high titered OS serum for the preincubation of the cell suspensions. Only preincubation with the IgM fraction of the anti-thyroglobulin antibodies resulted in the formation of significant numbers of passive rosette-forming cells.