Restricted expression of a human T cell lineage membrane antigen

An antiserum raised against human fetal and childhood thymocytes (anti-Thy) and absorbed with peripheral lymphocytes (tonsil) detected an antigen(s) shared by thymocytes, T cell-acute leukemias, activated peripheral T cells and a subset of peripheral T cells. The antigen was expressed by the negative circulating T cell subset after mitogen activation of that separated population. The antigen was shown to be separate from the E rosette receptor, another anti-T cell serum detected antigen, and beta 2-microglobulin; its expression was not related to a particular phase of the cell cycle. The results suggest that the antigen is expressed by T cells only under certain maturational and proliferative conditions.