Isolation of B lymphocytes for HLA-DR typing using monoclonal antibodies.

Isolating sufficient B cells for DR typing is often a problem, particularly in patients with low lymphocyte and/or B cell counts. This paper describes a simple method for preparing highly purified B cells using monoclonal antibodies and complement to kill the majority of non-B cells. Mononuclear cells are isolated by standard Ficoll-Hypaque techniques and incubated at 0 degrees C for 10 min with the following monoclonal antibodies: OKT3 (pan T cell), OKT11 (pan T and null cell), and Leu11b (NK cell). Rabbit complement is added and the mixture is incubated at 37 degrees C for 20 min. Dead cells are then removed by Percoll gradient centrifugation. This procedure results in cell preparations containing 90.1 +/- 1.3% B cells as measured by two-colow immunofluorescence with an Epics C flow cytometer. A yield of 52% can routinely be obtained. In contrast, nylon wool adherence results in preparations with only 44 +/- 9.1% B cells with a yield of 31%. B cells prepared by the monoclonal antibody procedure always show stronger and clearer reactions on DR typing trays. These results are consistent with the flow cytometric analyses of the B cell preparations. In summary, this procedure has the following advantages: increased accuracy of DR typing, decreased sample size (only 1.0 X 10(7) mononuclear cells are required), reduced time of cell preparation, and reduction in the number of repeat typings necessitated by poor yields and/or results.