MONOCLONAL-ANTIBODIES SPECIFIC FOR HUMAN-MONOCYTES, GRANULOCYTES AND ENDOTHELIUM

Abstract

Four monoclonal antibodies against antigens of human myeloid cells were produced and thoroughly characterized in terms of their reactions with peripheral blood cells, cell lines, 9 lymphoid and non-lymphoid tissues and the polypeptides with which they react. The antibodies UCHM1 and .**GRAPHIC**. identify antigens present on the majority of blood monocytes and a variable, but lower, proportion of tissue macrophages. From their morphology and location in tissues, these cells appear to be recirculating monocytes. .**GRAPHIC**. antigen is also present on platelets. Both antibodies also stained endothelial cells, .**GRAPHIC**. in all tissues examined and UCHM1 variably. Biochemical investigation indicated that the UCHM1 antigen is a protein of 52,000 MW while the .**GRAPHIC**. antigen could not be indentified. The antibodies TG1 and 28 identify antigens mainly present on granulocytes. While 28 reacted with neutrophils, TG1 also stained esoinophils and stained strongly a proportion of monocytes. TG1 also reacted variably with some non-hemopoietic cell lines. Both antibodies reacted predominantly with granulocytes in tissue sections. TG1 precipitated a single polypeptide of 156,000 MW from monocytes and granulocytes, while 28 precipitated non-convalently associated polypeptides of 83,000 and 155,00 MW from granulocytes but only a single molecule from monocytes, corresponding to the lower MW chain of 83,000. The epitope with which 28 reacts appears not to be exposed on the surface of intact monocytes. This suggests that a similar or identical 83,000 MW molecule is made by both neutrophils and monocytes, but that its expression differs according to cell type.