Insignificant immune phagocytosis inhibition and cytotoxicity by the murine monoclonal HLA-DP antibody B7/21 tested on human monocytes and macrophages.

On the basis of fluorescence flow cytometry data with the monoclonal antibody (MoAb) B7/21, and of the differing cell sizes, the HLA-DP antigen density on monocytes is estimated to be 25% of that on B lymphocytes. The remote positions of the antigens are assumed to be responsible for the markedly reduced inhibitory capacity of the MoAb B7/21 in immune phagocytosis by monocytes and for the absence of complement-dependent cytotoxicity of this MoAb to monocytes. The findings from experiments on peritoneal macrophages are comparable. Therefore HLA-DP may not be important for the functioning of the monocytes and macrophages.