Antibodies to cell surface antigens detected by a rapid spot test using ethidium bromide

We describe here a spot test to detect antibodies to non-erythroid cell surface antigens, using ethidium bromide staining to visualize areas of target cell lysis. This assay allows rapid screening of large numbers of samples of culture supernatants, antisera, or ascitic fluids. Antibody titers determined by this spot test are shown to correlate well with titers determined by two other methods, providing a simple method for initial estimation of the amount of antibody in positive samples.