Demonstration that antigen-binding cells are precursors of antibody-producing cells after purification with a fluorescence-activated cell sorter.

We have obtained viable and functional populations of antigen-binding cells enriched up to 500-fold from primed spleen-cell suspensions by fluorescent labeling and by a new electronic cell sorter that sorts viable cells according to fluorescence. Concomitantly, populations largely depleted of antigen-binding cells were obtained. While neither population alone is capable of a full adoptive secondary response when injected into irradiated recipients, a reconstituted mixture restores the full response of the unfractionated spleen cells. Admixture of sources of unprimed thymus-derived cells (T-cells) with the purified antigen-binding cells (B-cells) restores much of the full response.