Table 3. Phenotypic characteristics of Human regulatory B-cell subsets.

Breg Type	Phenotype	Key feature	Ascribed function
B10	CD24hiCD27+	Found in human blood, produce IL-10, and suppress effector CD4+ T cells and monocyte function	23, 26, 55
Transitional B cells	CD19+CD24hiCD38hi	Produce IL-10, found in blood and at site of inflammation, induce Treg cells, suppress Th1 and Th17 cells, suppress virus specific CD8+ T-cell responses	25, 27, 56, 57
Memory B cells	CD19+CD27+IgM+	Produce IL-10 and found in human blood. Suppress CD4+ T-cell proliferation and effector function	27
Plasmablast	CD19+CD38hiCD24hi CD27int	Produce IL-10, found in human blood and suppress DCs and effector CD4+ T cells	43, 58
GrB+ B cells	CD19+CD38+CD1dhi IgM+CD147+	IL-21 induced Granzyme B-expressing B cells suppressed T-cell proliferation	59
Br1 cells	CD19+CD25hiCD71hi CD73lo	Found in blood and produce IL-10 and IgG4	60

Abbreviations: Br1, B regulatory 1; DC, dendritic cell; IgG4, immunoglobulin G4; NK, natural killer.