Two distinct subpopulations of marginal zone B cells exhibit differential antibody-producing capacities and radioresistance

Marginal zone(MZ)B cells,which are splenic innate-like B cells that rapidly secrete antibodies(Abs)against blood-borne pathogens,are composed of heterogeneous subpopulations.Here,we showed that MZ B cells can be divided into two distinct subpopulations according to their CD80 expression levels.CD80^(high)MZ B cells exhibited greater Ab-producing,proliferative,and IL-10-secreting capacities than did CD80^(low)MZ B cells.Notably,CD80^(high)MZ B cells survived 2-Gy whole-body irradiation,whereas CD80^(low)MZ B cells were depleted by irradiation and then repleted with one month after irradiation.Depletion of CD80^(low)MZ B cells led to accelerated development of type II collagen(CII)-induced arthritis upon immunization with bovine CII.CD80^(high)MZ B cells exhibited higher expression of genes involved in proliferation,plasma cell differentiation,and the antioxidant response.CD80^(high)MZ B cells expressed more autoreactive B cell receptors(BCRs)that recognized double-stranded DNA or CII,expressed more immunoglobulin heavy chain sequences with shorter complementarity-determining region 3 sequences,and included more clonotypes with no N-nucleotides or with B-1a BCR sequences than CD80^(low)MZ B cells.Adoptive transfer experiments showed that CD21^(+)CD23^(+)transitional 2 MZ precursors preferentially generated CD80^(low)MZ B cells and that a proportion of CD80^(low)MZ B cells were converted into CD80^(high)MZ B cells;in contrast,CD80^(high)MZ B cells stably remained CD80^(high)MZ B cells.In summary,MZ B cells can be divided into two subpopulations according to their CD80 expression levels,Ab-producing capacity,radioresistance,and autoreactivity,and these findings may suggest a hierarchical composition of MZ B cells with differential stability and BCR specificity.