Technical aspects of the macrophage electrophoretic mobility test in transplantation immunity.

Transplantation immunity against a product of the D-region of mouse H-2 gene complex was examined by the macrophage electrophoretic mobility assay. The results obtained with the MEM assay depended upon selection of the guinea pig peritoneal exudate macrophages used for measurements. The macrophages 16--20 micrometers in diameter and containing liquid paraffin droplets were best suited for electrophoretic mobility measurements. The cells, containing liquid paraffin droplets but smaller than 16 micrometers in diameter, were affected by lymphocyte-antigen interaction product(s) much less. The increasing antigen concentration resulted in a sharp rise of macrophage percentage slowing from zero but reached a plateau value. The critical number of lymph node cells for a significant response was not less than 10(5) cells and there was a direct relationship between the number of lymphocytes and the magnitude of the response.