Figure 5.

ES-62 modulates the levels of B1-like cells in the spleen and LNs of mice with collagen-induced arthritis (CIA). There is no unambiguous phenotype for B1 cells in the spleen but they have been described as CD19^high CD23⁻ CD43⁺ IgM^high IgD^low/− CD5^± cells where CD5⁺ B1a and CD5⁻ B1b comprise ˜2% and 1% of cells in the spleen, respectively.²⁴ However, following gating on CD19⁺ IgM⁺ (a), analysis of CD43⁺ CD5^± cells has been widely used to describe B1 cells^25,26 whereas CD19⁺ CD5⁺ gating has been used to describe B1a cells.²⁸ Moreover, although CD43 can be up-regulated on B2 cells, this is usually expressed at a lower level than on B1 cells²⁷ and we have therefore chosen to gate only on CD43^high cells (b) so as to exclude any potential CD43⁺ B2 cells. We have therefore phenotyped CD19^high CD43⁺ IgM^high B cells as CD5⁺ B1a-like cells and CD5⁻ B1b-like cells and the data show their relative proportions in the spleen (c; naive, n = 10; PBS, n = 13 and ES-62, n = 11) and draining lymph node (d; naive, n = 4; PBS, n = 8 and ES-62, n = 8) of the indicated groups of mice.