Antibody response in aged C57BL/6 mice: T helper cells are responsible for the decline of the primary antibody response to a bacterial antigen in aging.
One of the most important effects of aging is the decline of immune effectiveness. A study is described here on the primary (IgM) antibody response to phosphorylcholine (PC), an antigen expressed on the surface of the Streptococcus pneumoniae R36a, in aged (18-22 mo.) C57BL/6 mice. Preliminary data showed a significant decrease of PC-specific response in aged mice as compared to young/adult (3-4 mo.) syngeneic mice. In vitro studies showed that B cells from aged donors, retained the ability to produce amounts of anti-PC antibody comparable to that of B cells from young donors. In addition, B cells from young and aged donors were cultured in the presence of L3T4 or Lyt2 T cells obtained from donors of different ages. "Aged" L3T4 cells failed to augment the anti-PC response, as compared to the young ones, while the Lyt 2 cells, either from young or aged donors, showed no effects on the anti-PC response. These observations were confirmed by in vivo selective depletion of T cells subpopulations in both young and aged C57BL/6 mice. L3T4 cell-depleted young mice displayed a markedly reduced antibody response; in contrast, age-depleted mice did not show any significant modifications of the response as compared to normal aged mice. Furthermore, we observed that the selective depletion of Lyt 2 cells in both young and aged C57BL/6 did not alter the anti-PC response in any way.
Nicoletti
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Institute of Human Anatomy, University of Siena, Italy.
D000375:Aging / Q000276:immunology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D008212:Lymphocyte Depletion; D051379:Mice; D008810:Mice, Inbred C57BL; D010767:Phosphorylcholine / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000907:Antibodies, Bacterial; D010767:Phosphorylcholine