Use of Monocytes in HLA-A, B, C and DR Typings

Abstract

A simple method of improved serologic typing of [human] monocytes for HLA-A, B, C and DR specificities is described. The method employs monocytes recovered from frozen samples of peripheral blood mononuclear cells; it chiefly involves pretreatment of monocytes with 0.01% iodoacetamide (IAA) prior to typing. The principal advantage of this method is in the lowering of the background nonspecific cytotoxicities and false positive readings upon IAA addition to the monocyte preparations. Using this method monocytes can be typed for HLA-A, B, C determinants. Although addition of IAA results in substantial typing improvements, assignment of A, B, C specificities was difficult due to the presence of extra positive reactions when monocytes were compared to T [thymus-derived] lymphocyte typings, probably due to the presence of DR or monocyte specific antibodies in the routinely used HLA antisera. This method was most useful in DR typings where monocytes in the presence of IAA were compared with autologous B [bone marrow-derived] cells in the absence of IAA. Differences in typings due to a decrease in false positive cytotoxic readings were significantly in favor of using IAA treated monocytes in DR typings (P < 0.0001). The use of IAA in the course of B cell or T cell typings had no adverse consequences on A, B, C or DR typings. These results indicate potential usefulness for the use of IAA in typing monocytes for HLA determinants in general and for the DR determinants in particular.