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Antigen-binding B cells and polyreactive antibodies
Z J Chen1, J Wheeler, A L Notkins
1Laboratory of Oral Medicine, National Institute of Dental Research, National Institutes of Health, Bethesda 20892.
The present experiments were initiated to see if cells capable of binding antigens could make polyreactive antibodies. Fluorescein isothiocyanate-labeled self and non-self antigens were incubated with B cells from normal individuals. Antigen-binding cells were separated from non-antigen-binding cells by flow cytometry, immortalized with Epstein-Barr virus and analyzed at the clonal level for their capacity to make polyreactive antibodies. Four to six times more cells making polyreactive antibodies were found in the B cell subset that bound antigens than in the B cell subset that did not bind antigens. The majority of the polyreactive antibodies were of the immunoglobulin (Ig)M isotype. Immunoflow cytometry revealed that cell lines making polyreactive antibodies bound a variety of antigens (e.g., insulin, IgGFc and beta-galactosidase), whereas cell lines making monoreactive antibodies bound only a single antigen. The binding of antigens to B cell lines that made polyreactive antibodies could be inhibited (range, 28%-57%) by both homogeneous and heterogeneous antigens. Both CD5+ and CD5- antigen-binding B cells made polyreactive antibodies, but the frequency was slightly higher in the CD5+ antigen-binding (85%) as compared to the CD5- antigen-binding (50%) population. Comparison of CD5+ B cells that bound antigens with CD5+ B cells that did not bind antigens showed that approximately 86% of the former, but only 15% of the latter, made polyreactive antibodies. It is concluded that cells capable of binding a variety of different antigens can make polyreactive antibodies and that antigen binding is a good marker for identifying polyreactive antibody-producing cells.
The present experiments were initiated to see if cells capable of binding antigens could make polyreactive antibodies. Fluorescein isothiocyanate-labeled self and non-self antigens were incubated with B cells from normal individuals. Antigen-binding cells were separated from non-antigen-binding cells by flow cytometry, immortalized with Epstein-Barr virus and analyzed at the clonal level for their capacity to make polyreactive antibodies. Four to six times more cells making polyreactive antibodies were found in the B cell subset that bound antigens than in the B cell subset that did not bind antigens. The majority of the polyreactive antibodies were of the immunoglobulin (Ig)M isotype. Immunoflow cytometry revealed that cell lines making polyreactive antibodies bound a variety of antigens (e.g., insulin, IgGFc and beta-galactosidase), whereas cell lines making monoreactive antibodies bound only a single antigen. The binding of antigens to B cell lines that made polyreactive antibodies could be inhibited (range, 28%-57%) by both homogeneous and heterogeneous antigens. Both CD5+ and CD5- antigen-binding B cells made polyreactive antibodies, but the frequency was slightly higher in the CD5+ antigen-binding (85%) as compared to the CD5- antigen-binding (50%) population. Comparison of CD5+ B cells that bound antigens with CD5+ B cells that did not bind antigens showed that approximately 86% of the former, but only 15% of the latter, made polyreactive antibodies. It is concluded that cells capable of binding a variety of different antigens can make polyreactive antibodies and that antigen binding is a good marker for identifying polyreactive antibody-producing cells.