Membrane expression of Thy-1,2 and GM1 ganglioside on differentiating T lymphocytes.

C3H mouse bone marrow cells were separated by discontinuous BSA gradient centrifugation. Marrow cells from the 17 to 19%, 19 to 21% to 23%, 23 to 25%, 25 to 27% interfaces and the cell pellet were treated with thymic factor (TF) or with Vibrio cholerae neuraminidase (VCN), followed by anti-Thy-1,2 and anti-GM1 ganglioside antisera. Antigens determined by anti-Thy-1.2 or anti-GM1 were expressed either with TF or VCN within a 30-min incubation. Cells expressing these antigens after VCN or TF treatment were concentrated in the 19 to 21% layer and the 21 to 23% layer whereas there was little or no antiserum cytotoxicity in the other layers. A small amount of Thy-1.2 of GM1 could be detected by cytotoxicity on 19 to 21% layer marrow cells within 15 min of either TF or VCN treatment. Treatment of 19 to 21% layer cells with TF or VCN had no effect on anti-H-2 cytotoxicity. Pretreatment of TF-treated marrow cells with cholera toxin or choleragenoid (which bind cell surface GM1) abrogated the cytotoxicity of anti-Thy-1.2 or anti-GM1 without affecting anti-H-2 cytotoxicity. Pretreatment of Thy-1.2 positive C3H thymocytes with cholera toxin or choleragenoid greatly reduced the cytotoxicity of anti-Thy-1.2 antisera without affecting the cytotoxicity of anti-H-2 antisera. Nude mouse splenocytes, after treatment with VCN or TF, were susceptible to the lytic action of anti-Thy-1.2 and anti-GM1. The possibility that nonspecific autologous antibodies were responsible for anti-Thy-1.2 cytotoxicity toward VCN-treated marrow cells was eliminated because anti-Thy-1.2 was not cytotoxic for VCN treated AKR (Thy-1.1) marrow cells.