Variance in the resistance of murine early bone marrow B cells to a deficiency in zinc

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Abstract
Little is known of the effects of nutritional deficiencies on lymphopoietic processes. Nevertheless, deficiencies in zinc adversely affect immune function causing thymic atrophy and lymphopenia in both humans and animals. Previous studies of the effects of zinc deficiency (ZD) on lymphopoiesis in adult mice indicated that a suboptimal intake of zinc caused a 50% or more depletion of the marrow of developing B cells. Thus, interference in the production of lymphocytes by ZD appeared to be a significant factor in the loss of host defence capacity. In the current study three-colour immunofluorescence phenotyping of early bone marrow B lymphocytes (B220+ immunoglobulin-) using flow cytometry demonstrated that a 27-day period of ZD caused a 50-70% decline in pre-B cells (B220+ CD43- immunoglobulin M (IgM)-) for moderate and severely zinc-deficient mice, respectively. Conversely, early pro-B cells (B220+ CD43+ 6C3-) and late pro-B cells (B220+ CD43+ 6C3+) exhibited little or no change in their distribution within the marrow. Indeed, the greater resistance of pro-B cells resulted in a 50% increase in the proportion of this subset within the B-cell compartment of the marrow as the deficiency in zinc advanced. Collectively, the data indicate that the B-cell compartment of the marrow is substantially altered by ZD and the stage specific sensitivity noted among early B cells may be related to chronically elevated levels of glucocorticoids present during ZD or other parameters that affect their survival and resistance to apoptosis.