label: Increased immature B cell proportion
label_lc: increased immature b cell proportion
description: An elevation in the proportion above normal of immature B cells (CD19+/ CD21low) in circulation relative to total number of B cells. Immature B cells (IgM+) are still in final stages of development within the bone marrow. Naive B cells are those which have left the bone marrow, before they bind to the antigen for which they're specific (IgM+/IgD+).