Bacteria as an indicator of formation of antibodies by single spleen cells in agar

Bacteria can be used to measure the formation of specific antibody by suspensions of single spleen cells. The technique, based on localized immune lysis (plaque formation) in agar, permits assays on the kinetics of increase in the number of cells forming bactericidal antibody in the spleen of immunized mice. The procedure also is useful for testing nonspecific stimulation of antibody synthesis and for analyzing spleen cell populations from donors that have been immunized simultaneously with bacterial and red blood cell antigens.