CD4 and nutritional deficiency disease: Absolute numbers of some thymic and splenic T-cell sub-populations were reduced in zinc deficient rats compared to both pair-fed and ad libitum-fed control rats [splenic TCR+CD4+CD8− (helper T-cells), splenic TCR+CD4−CD8+ (cytotoxic T-cells)] while other reductions occurred in both zinc deficient and pair-fed rats [thymic TCR−CD4+CD8+ and TCR+CD4+CD8+ (both pre T-cells)] indicating an effect of malnutrition.