Aging effects on T-bet expression in human B cell subsets.

In order to compare human and mouse B cell subset markers, we evaluated T-bet expression in human B cell subsets from individuals of different ages. We found T-bet expressed in unstimulated memory more than naïve B cells, and more in young individuals. TLR7 stimulation up-regulated T-bet in all B cell subsets from young and elderly individuals, and more in the elderly. By fold-increase the best effect was seen in subsets of the elderly and especially in those that undergo class switch (naïve and IgM). We also evaluated CD11c expression, as T-bet+CD11c+ B cells are expanded in healthy elderly individuals and also in patients with autoimmunity. Similar to T-bet, CD11c expression was higher in memory than in naïve B cells, but no differences were observed between young and elderly individuals. After TLR7 stimulation, CD11c increases in all B cell subsets (especially in naïve and IgM) from the elderly.