Immunocytochemical localization of the immunoglobulin factors Gm(a), Gm(b) and Inv(a) in human lymphoid tissue

Fluorescent antibodies to the human immunoglobulin allelic characters Gm(a) and Gm(b) were found to be localized in different plasma cells in the red pulp of the spleen and the medullary cords of the lymph nodes of heterozygous Gm(a⁺ b⁺) individuals. Approximately 45 per cent of the cells, which were subsequently shown to contain immunoglobulin after bleaching the section and restaining with fluorescent anti-whole human immunoglobulin, reacted with the fluorescent anti-Gm(a), 25 per cent with the fluorescent anti-Gm(b) and 30 per cent did not react at all. Sections already labelled with the fluorescein anti-Gm(a) and rhodamine anti-Gm(b) upon staining with fluorescein anti-Inv(a) showed approximately 60 per cent of all cells with mixed fluorescence and 25 per cent previously unlabelled cells fluorescing with the Inv(a) label only. In Gm(a⁺ b⁺ x⁺) individuals Gm(a) and Gm(x) seemed to be localized in the same plasma cells. However, in the germinal centres of the lymph nodes and the white pulp of the spleen Gm(a), Gm(b) and Inv(a) appeared to be contained in the same cells.