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. Author manuscript; available in PMC: 2021 Feb 1.
Published in final edited form as: Arterioscler Thromb Vasc Biol. 2019 Dec 19;40(2):309–322. doi: 10.1161/ATVBAHA.119.313064

Figure 3. Human B-1 cells.

Figure 3.

Human B-1 cells were identified in peripheral and cord blood by Rothstein and colleagues as a CD20+CD3-CD27+CD43+ population. Functionally, this subset spontaneously secretes IgM, exhibits tonic intracellular phospholipase C gamma 2 (PLC-g2) and Syk phosphorylation, and efficiently stimulates T cell proliferation. Heterogeneity has been demonstrated within the human CD20+CD3-CD27+CD43+ B-1 population differentiated by CD11b expression. Human B-1 cells with low or no CD11b expression are better able to spontaneously secrete IgM, thus are termed “B-1 secretors.” CD11b+ human B-1 cells have been demonstrated to express higher levels of CD86 and to more efficiently stimulate allogeneic CD4+ T cell proliferation compared to B-1 secretors. CD11b+ B-1 cells also spontaneously secrete IL-10, which is able to suppress intracellular TNF-a expression by anti-CD3 stimulated T cells in vitro. CD11b+ B-1 cells are termed “B-1 orchestrators” due to their increased capacity to modulate T cell activation and proliferation. In contrast to murine B-1 cells, an equivalent B-1a/B-1b dichotomy has not been identified in the human B-1 cell subset.