Cell surface phenotype of the spontaneous immunoglobulin-secreting cells in peripheral blood from homosexual men with generalized lymphadenopathy or AIDS.

Activated B cells that spontaneously secrete immunoglobulin are found in homosexual men with AIDS or lymphadenopathy. These cells constitute a very small percentage of peripheral blood lymphocytes (usually less than 1%), making identification of their surface antigens difficult. To identify surface antigens on immunoglobulin-secreting cells, peripheral blood mononuclear cells were first reacted with monoclonal antibody, followed by a fluorescein-conjugated goat antimouse globulin reagent. Secretion of immunoglobulin was then assessed in a reverse hemolytic plaque assay, with a modified Cunningham chamber in which an individual plaque-forming cell could be examined with a fluorescence microscope. All plaque-forming cells were found to be reactive with OKT 10 and 4F2 monoclonal antibodies; there was moderate reactivity with anti-la and B4. The same results were found when normal pokeweed mitogen-stimulated lymphocytes were tested. The surface phenotype of these cells is consistent with that of a preplasma cell.