TEMPORAL DYNAMICS OF CD69 EXPRESSION ON LYMPHOID-CELLS

Lymphocyte activation remains an area of intense interest to immunolog ists and cell biologists and the dynamics of expression of surface mol ecules during the process are widely studied. The CD69 C-type lectin i s reportedly the earliest activation antigen on lymphocytes and can be detected within hours of mitogenic stimulation. Recently reports have described differential activation dynamics with respect to different antigenic or mitogenic stimuli. This study has investigated the dynami cs of CD69 expression over time after mitogenic, allogeneic, cytokine and target cell mediated activation of T-cell and NK cell subsets. It is apparent that the dynamics of CD69 expression differ with respect t o the cell type and the method of stimulation. Mitogenic stimulation r esulted in the most rapid expression of CD69 on both T-and NK cells wh ile alloantigen stimulation induced a far slower response. Target cell stimulation of NK cells gave paradoxical results in that the CD69 + v e subset increased as a proportion of the total NK cells but did not i ncrease in number. This was due to the selective binding of CD69 - ve NK cells to the target cells and their subsequent loss from the lympho id gate. We confirmed this by showing that CD69 + ve NK cells do not l yse K562 target cells. This observation demonstrates the caution neede d in the analysis of flow cytometric data based solely upon relative p roportions of cells within discrete subsets. (C) 1997 Elsevier Science B.V.