Two phenotypically distinct B lymphocytes (IgM(high)IgD(low) and IgM(low)IgD(high)) in chronic gastric ulcer in the rat

We determined the kinetics and phenotypes of infiltrating B cells in gastric ulcer in the rat induced by gastric injection of acetic acid (day 0). Few B cells were found in the lesion in the early stages of ulceration. On day 40, two kinds of B cells with phenotypes of IgM(high)IgD(low)OX33 (CD45)⁺OX19 (CD5)^- and IgM(low)IgD(high)OX33 (CD45)⁺OX19 (CD5)^- were scattered in the granulation tissue of open ulcers, but not in the healed scar tissue. On day 180, those two kinds of B cells formed primary follicles in the granulation tissue of open ulcers, but were absent from the healed scar tissue. The IgM(high)IgD(low)OX33 (CD45)⁺OX19 (CD5)^- B cell was considered to be identical to the marginal zone B cell of rat spleen. This phenotype of B cell might be associated with inflammatory process in chronic gastric ulcer.