Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

An Fc gamma receptor I (CD64) negative subpopulation of human peripheral blood monocytes is resistant to killing by antigen activated CD4-positive cytotoxic T cells

Abstract

It has been demonstrated that in monocyte/T cell co cultures activated with recall antigens, cytotoxic T cells were generated which are able to reduce the number of antigen presenting monocytes. In previous studies we could show that a minor subset of monocytes, the Fc gamma receptor I negative (CD64(-)) monocytes, exhibits significantly higher antigen presenting capacity than the main population of monocytes (> 90%) which are Fc gamma receptor I positive (CD64(+)). Therefore, we addressed the question whether they are also differentially susceptible to T cell mediated killing. In the present study we demonstrate that the CD64(-) monocyte subset is more resistant to killing by antigen activated T cells than CD64(+) monocytes, as indicated by a higher viability and recovery of CD64(-) monocytes. This mechanism involves CD95 (Fas) antigen, since monocyte death in co cultures with antigen activated T cells could be partially reduced by blocking anti Fas monoclonal antibodies (mAb). In agreement with this finding, although CD95 antigen was expressed on CD64(+) and CD64(-) monocytes at comparable levels, killing of CD64(-) monocytes by activating anti Fas mAb was lower than of CD64(+) monocytes.