G. Colonna-Romano, M. Bulati, A. Aquino, S. Vitello, G. Clesi, C. Caruso

The literature on immunosenescence has focused mainly on the roles of T cells in the induction of the immune response and in the generation of the immunological memory. On the other hand, little is known about the B cell memory. According to the expression of sIgD and CD27 as markers for B memory cells (1), we have studied nave and memory B lymphocytes in our aged population. Our data show a decrease of nave IgD+CD27- B cells and a slight (not statistically significant) increase of memory IgD-CD27+ B cells. No modifications are observed in the IgD+CD27+ population, whereas we observe a significant increase of the IgD-CD27- subset that, as suggested by Gagro et al (2), might be a subset of memory B cells. In our samples, the percentage of this subset is the same of those obtained for IgG+CD27- B cells. We have also evaluated another novel subpopulation of resting memory B cells identified by the expression of CD80 and CD27 that shows a low threshold of activation and ability to deliver a good memory effector response (3) . Our preliminary data show that this kind of B cells in elderly is increased. Hence, we hypothesize that memory B cell compartment in aged is shaped to ensure a robust secondary humoral immune response. In fact, although CD19 B cells are numerically decreased the lower threshold of activation of B cells renders them prompt to respond. Since information on the senescence of B cells is of obvious interest, further studies are necessary to confirm these preliminary results as well as to extend the number of markers used to characterize the cells.

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B memory