EFFECT OF ASCORBIC-ACID NUTRITURE ON BLOOD HISTAMINE AND NEUTROPHIL CHEMOTAXIS IN GUINEA-PIGS

Histamine suppresses certain immune responses, including neutrophil chemotaxis. The present study examined whether the histamine-lowering effect of ascorbate was accompanied by enhanced chemotaxis in guinea pigs. Animals were fed low ascorbate, adequate or high ascorbate diets (0.5, 2.0 or 50 mg ascorbate.100 g body wt-1.d-1) for 4 wk. Mean liver ascorbate paralleled dietary intake, and these values differed significantly. Blood histamine was significantly depressed in the high ascorbate group compared to the adequate and low ascorbate groups, and liver ascorbate was inversely correlated to blood histamine levels (r = -0.64, P < 0.001). The random migration of neutrophils was not significantly affected by vitamin dosage. Leukocyte chemotaxis was significantly impaired in low ascorbate animals compared to that of animals with adequate ascorbate nutriture. Leukocyte chemotaxis in high ascorbate animals did not differ significantly from that in the adequate or low ascorbate groups. Furthermore, chemotaxis was significantly lower when cells extracted from animals with adequate ascorbate nutriture were incubated in low ascorbate or high ascorbate serum rather than in autologous serum. These data suggest that the histamine-lowering effect of supplemental ascorbate does not appear to enhance leukocyte chemotaxis and that serum from guinea pigs fed low or high levels of ascorbate appears to contain factors that depress chemotaxis.