The effect of 1 alpha-hydroxyvitamin D3 on primary antibody formation in mice

The immunoregulatory effect of 1 alpha-hydroxyvitamin D3, a precursor form of active vitamin D3 (1,25-dihydroxyvitamin D3), was examined in three different kinds of experimental systems in mice. Oral administration of 0.05 and 0.2 micrograms/kg of 1 alpha-hydroxyvitamin D3 augmented the primary immune response induced by immunization with 1 X 10(7) sheep erythrocytes, although it did not influence a maximal level of antibody formation induced by immunization with 5 X 10(8) sheep erythrocytes. The same treatment also restored the immune response depressed by restraint-stress. Furthermore, 1 alpha-hydroxyvitamin D3 suppressed the anti-dinitrophenyl plaque-forming cell response enhanced by colchicine injection to near the normal level. These results suggest that 1 alpha-hydroxyvitamin D3 enhanced or suppressed the immune response through activating helper and suppressor cells in dependence on the magnitude of the response.