Direct Demonstration of Theta-positive Antigen-binding Cells, with Antigen-induced Movement of Thymus-dependent Cell Receptors

Anti-thetaAKR antibody conjugated to fluorescein has been used in direct immunofluorescence tests to identify spleen theta(+) (T) sheep erythrocyte rosette-forming cells in AKR mice. Specificity studies involving A and cogenic A/thetaAKR mice clearly demonstrated that the cell surface fluorescence and cytotoxicity produced by the antiserum is directed solely toward the thetaAKR alloantigen. Approximately (3/8) of rosette-forming and non-rosette-forming spleen cells were found to be theta(+). The tendency for T cells to bind less antigen and the tendency for antigen-binding T cells to bear less theta than other spleen T cells, first suggested by other studies involving rosette-elimination by anti-thetaC3H plus complement, were confirmed by direct immunofluorescence. All AKR rosettes are specifically inhibitable by anti-immunoglobulin, including T rosettes. Antigen-induced redistribution of T cell receptors, analogous to that previously described for B cell receptors (16), occurs as readily in theta(+)RFC as in theta(-) RFC, without altering the symmetrical ring distribution of thetaAKR antigen.