Depletion of cells of the B lineage in the bone marrow of zinc-deficient mice.

Though lymphopenia is often noted in malnourished humans and rodents, little is known about the effects of suboptimal nutriture on lymphopoietic processes. Focusing primarily on cells of the B lineage in the marrow of young adult mice, a moderate degree of zinc deficiency (MZD) caused a 43% decline in the proportion of nucleated cells bearing B220 with a 91% decline noted among more severely zinc deficient mice (SZD). Early B cells (B220+Ig-) were highly sensitive to the deficiency, being barely detectable in SZD mice and reduced by almost 60% in MZD mice. Immature B cells (B220+IgM+IgD-) were similarly affected, declining 35% to 80% depending on the degree of the deficiency. In MZD mice, mature B cells (IgM+IgD+) exhibited moderate losses, being somewhat resistant. A more profound loss in this population was noted for SZD mice. Flow cytometric (FACS) scatter profiles indicated that zinc deficiency caused a sharp decline in the proportion of small nucleated cells which in the marrow are thought to contain a high proportion of developing lymphoid cells. There was a concomitant increase in large granular cells that paralleled a substantial increase in the proportion of nucleated cells bearing Mac-1 for both MZD and SZD mice. Given the dramatic depletion of cells of the B lineage in the marrow created by a deficiency in zinc, it is probable that disruptions in lymphopoietic processes in the marrow play a key role in the resulting lymphopenia observed in many types of malnutrition.