Characterization of peripheral blood mononuclear cells expressing the VG01 antigen: their NK and memory function

This study describes VG01, a lymphocyte activation antigen of approximately 40 kd and the functional characteristics of VG01 circulating peripheral blood lymphocytes (PBL). We have previously described that VG01 is expressed by monocytes, the majority of CD16 lymphocytes, and a small fraction of circulating T lymphocytes. It is also newly expressed by T cells upon activation with mitogens and alloantigens and allows for the selection and enrichment in vitro of allospecific primed T lymphocytes. In this manuscript, we confirm that most, if not all, the NK activity resides in the VG01-enriched population. We also demonstrate that the memory response to PPD and Candida in previously sensitized normal individuals is found within the VG01+ cell fraction. In contrast, the proliferative response to PHA is significantly greater in the VG01-depleted PBL, but both cell fractions have an overall adequate proliferative response to this mitogen. The absence of proliferation to PPD and Candida by VG01-PBL is not due to differences in the kinetics of response because this cell fraction was almost devoid of responding cells when proliferation to the antigens was measured at different time intervals. Anti-VG01 has no effect in the in vitro lymphocyte proliferative response to antigens and mitogens. VG01 appears to be a lymphocyte activation antigen that includes circulating T memory cells and that at least in these cells appears to be permanently rather than transiently expressed.