Peripheral immunoglobulin secreting cells in immunodeficiencies; effects of intravenous immune globulin.

Peripheral blood B cells secreting IgG, IgA, IgM, and IgE were quantitated in normal adults (n = 12), newborns (n = 8), patients with antibody deficiency (n = 5), and patients with elevated IgE (four patients) using a reverse enzyme-linked immunospot (RELISPOT) assay. This technique measures immunoglobulin secreted by B cells by capture on an antibody-coated plate, and identified as a plaque on a nitrocellulose-membrane plate. Hypogammaglobulinemic patients and newborns (cord blood) showed no detectable IgG, IgA, or IgE secreting cells. Several cord blood and hypogammaglobulinemic patients, however, showed normal adult numbers of IgM secreting cells. One IgA-deficient patient showed increased numbers of IgA secreting cells, but a second IgA-deficient patient showed normal numbers of IgA secreting cells. Three patients with the hyper-IgE syndrome and a patient with severe eczema had very high numbers of IgE secreting cells. The effects of intravenous immunoglobulin on this system in vivo and in vitro were also examined. High dose intravenous immunoglobulin therapy did not decrease the immunoglobulin secreting cells in two neurologic patients given high dose IVIG. In vitro exposure of normal B cells to either IVIG or cycloheximide (a protein synthesis inhibitor) decreased the number of IgA and IgM secreting B cells. Cycloheximide also decreased the number of IgG secreting B cells in vitro. IgG spots, however, were present when cycloheximide-treated cells were incubated with a high concentration of IVIG. Since IVIG may bind directly to cells, its effect on in vitro B-cell IgG synthesis could not be determined.