Evaluation of cancer patient leukocyte responses in the presence of physiologic and pharmacologic pyridoxine and pyridoxal levels

Peripheral blood samples from six cancer patients (five colon cancer, one lung cancer) and six healthy volunteers were tested in vitro for oxygen radical production by phagocytic cells and in assays of mitogen‐induced lymphoblastogenesis at physiologic and pharmacologic concentrations of pyridoxine (PN, 1.8‐96 nmol/ml) or pyridoxal (PL, 0.08‐90 nmol/ml). Plasma levels of pyridoxal‐5′‐phosphate (PLP), 4‐pyridoxic acid (4PA), pyridoxamine phosphate (PMP), and PL were also determined. Phagocytic cells from three patients showed significantly increased capacity for oxygen radical production when incubated in PL‐, but not PN‐supplemented media. Oxygen burst capacity of cells from healthy subjects was significantly enhanced by PN‐, but not PL‐enriched media. Lymphocyte responsiveness to phytohemagglutinin or pokeweed mitogen (PWM) stimulation showed a modest increase in cell activation in three patients as the concentration of PN was increased; with concanavalin A, two showed enhanced responsiveness. On the other hand, PL‐supplementation resulted in greater cell proliferation only with PWM. The cancer patients had significantly lower plasma PLP, 4PA, and PMP levels when compared with the healthy volunteers. These data indicate that in the cancer patients and in a majority of the healthy volunteers, vitamin 6‐6 status was marginal or deficient and suggest that increasing PN or PL in vivo levels may augment functions related to cell‐mediated immunity.