title: IgG on infants' B lymphocytes: enhanced binding of IgG by Ig M-bearing lymphoid cells in early childhood.
abstract: IgM/IgD-bearing lymphocytes (B cells) from children in the first few weeks of life were found to also have surface IgG, unlike most normal adult B cells. The IgG was loosely bound to the lymphocyte surface and was partially or completely removed by incubation at 37 degrees C or by trypsinization. When F(ab')2 antisera were employed, very few infant B cells had surface IgG, although the IgM staining was similar to that obtained with the native antisera. IgM/IgD-positive cells bound IgG anti-Rh-coated (Ripley) erythrocytes, unlike most adult B lymphocytes. Capping experiments suggested that an Fc receptor on the cells could be redistributed by the anti-IgM-surface IgM complex. These data indicate that, during infancy, B-lymphocyte receptors for IgG are of altered affinity, frequency, or availability compared with adult B-lymphocyte Fc receptors and resemble the Fc receptors found on "third population" (Fc + Ig-) mononuclear cells and monocytes.
mesh_terms: D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D001666:Binding Sites, Antibody; D002478:Cells, Cultured; D005453:Fluorescence; D005455:Fluorescent Antibody Technique; D006801:Humans; D007104:Immune Adherence Reaction; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism; D007202:Indicators and Reagents; D007231:Infant, Newborn; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D013194:Staining and Labeling; D014357:Trypsin / Q000494:pharmacology
chemical_list: D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007202:Indicators and Reagents; D011947:Receptors, Antigen, B-Cell; D014357:Trypsin