Effects of injectable beta-carotene and vitamin A on lymphocyte proliferation and polymorphonuclear neutrophil...

Newborn piglets were injected with either (1) vehicle; (2) 20 mg beta-carotene; (3) 40 mg beta-carotene; (4) 25,000 IU vitamin A palmitate, or (5) 50,000 IU vitamin A palmitate. Blood was collected at 0.5, 1, 3, and 6 weeks of age and lymphocyte proliferation, polymorphonuclear neutrophil (PMN) phagocytosis and intracellular killing of live Escherichia coli were measured. Lymphocyte proliferation in all piglets was high at birth but decreased thereafter. Piglets injected with either high beta-carotene or vitamin A palmitate showed higher phytohemagglutinin- and pokeweed mitogen-induced lymphocyte proliferation at week 3 compared to controls. Similar results were seen with 20 micrograms/ml concanavalin A in piglets injected with high vitamin A palmitate. Phagocytosis by PMN isolated from all piglets decreased to a nadir at week 3 but returned to values observed in the newborn by week 6. Treatment had no effect on phagocytosis. Piglets injected with beta-carotene or vitamin A palmitate had lower intracellular killing ability at week 3 compared to controls. Therefore, beta-carotene and vitamin A palmitate enhanced mitogen-induced lymphocyte proliferation but reduced killing ability by PMN in piglets.