Rhesus Monkey B Lymphocyte Surface Immunoglobulin: Analysis with a Fluorescence-Activated Cell Sorter

Abstract

Rhesus monkey spleen, mesenteric lymph node, peripheral lymph node, blood, thymus, and bone marrow mononuclear cell suspensions were stained with fluorescein-conjugated F(ab′)₂ fragments of affinity-purified rabbit anti-human Fab, rabbit anti-human γ, rabbit anti-human µ, rabbit anti-human δ, and/or rabbit anti-human α as well as rabbit anti-keyhole limpet hemocyanin (RaKLH) and analyzed for fluorescence intensity and frequency of positive cells with a fluorescence-activated cell sorter. Greater than 90% of surface (s)IgM-bearing spleen, blood, and lymph node lymphocytes bore sIgD, whereas only approximately 40% of sIgM-bearing bone marrow lymphocytes had sIgD. In all of these organs greater than 90% of sIgD-bearing cells also had sIgM. Substantially smaller numbers of lymphocytes bore sIgG than sIgM or sIgD, and most sIgG-bearing cells in all organs studied lacked sIgM and sIgD. Few if any cells in any organ studied bore detectable sIgA, and less than 1% of thymus cells had any sIg. B cell populations from spleen, peripheral lymph node, and mesenteric lymph node averaged similar quantities of sIgM and sIgD per B cell. Blood B cells averaged twice as much sIgM and sIgD as B cells from spleen and lymph node, and 9 times as much sIgD as sIgD⁺ bone marrow cells. sIgD⁺ bone marrow B lymphocytes have considerably more sIgM than sIgD^- sIgM⁺ bone marrow B cells. Our data confirm that the sIgD⁺ sIgM⁺ cells are the predominant B lymphocyte in primates, and suggest that monkey B cells acquire sIgD in the marrow before migrating to other lymphoid organs.