Quantitative Determination of Antibody and Complement Directed against Lymphocytes

Abstract

A rapid, precise method is presented for the quantitative assay of cytotoxic antibody and complement levels employing lymphocytes as the target cell. The technique consists essentially of enumerating with the electronic Coulter Counter the number of “normal size cells” remaining after incubation with antibody and complement. Death of lymphocytes as appraised by eosin dye exclusion was paralleled by a loss in numbers of electronically countable cells, though simultaneous counts made in the hemocytometer indicated that the cells do not actually disappear. Thus dead cells are apparently not “seen” by the electronic counter. Plots of the reduction in normal size cells produced by allogenic mouse antisera or complement were shown to be linear by the method of probits or the von Krogh equation. The technique was highly sensitive, for cytotoxicity of some mouse antisera produced against homografts could be detected with as little as 0.00005 ml.