The short lived suppressor cell assay and its relationship with mitogen responsiveness in normal individuals

The short lived suppressor cell(SLSC) assay is an indirect test for spontaneous suppressor cell activity based on the principle that some suppressor cells are short lived in culture. It measures the ratio (suppressor index) between 3H-thymidine incorporation by lymphocytes stimulated by concanavalin-A (Con-A) after 24 hours of preincubation (during which SLSC are lost) to that incorporated by cultures stimulated immediately (SLSC present). In autoimmune conditions decreased suppressor indices are reported but low responses to mitogen stimulation also occur. The aim of this study was to investigate whether low levels of mitogen responsiveness could lead per se to low suppressor indices. A simultaneous analysis of suppressor indices and mitogen responses to Con-A, PHA and PWM of peripheral blood mononuclear cells in normal individuals was performed. There was an inverse correlation between responses to Con-A or PHA and the suppressor indices, indicating that low mitogen responsiveness does not lead per se to decreased SLSC activity and furthermore that the activity of SLSC may modulate lymphocyte reactivity in vitro.