Plaque assay with protein A-coated erythrocytes for the evaluation of human immunoglobulin-secreting cells induced by pokeweed mitogen.

Cells secreting IgM, IgG and IgA were evaluated in cultures of human peripheral blood lymphocytes stimulated in vitro with pokeweed mitogen by a haemolytic plaque assay using protein A-coated erythrocytes in the presence of class-specific antisera. Kinetic study revealed that immunoglobulin-secreting cells appeared after 3 days of culture and peaked between days 5 and 7. IgM-secreting cells predominated throughout the culture period. This plaque assay is a useful and sensitive in vitro test for the evaluation of polyclonal B-cell activation in humans and may provide a good approach to the study of disturbances in the synthesis of the various classes of immunoglobulins.