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While many studies have investigated the overall nutritional status of children with cancer, the status with regard to vitamin B6 has not been investigated. Vitamin B6 is an important factor in over 100 different chemical reactions within cells. It has been hypothesized by some that abnormalities in vitamin B6 metabolism could play a role in the development of cancer. For this reason, the vitamin B6 status was investigated in 37 children with leukemia and in 37 age-matched controls. The study examined the plasma levels of pyridoxal 5'-phosphate (PLP), which is the biologically active form of the vitamin; it is generally believed that the circulating plasma levels of this vitamin are a fair indication of the total body store. It was found that the patients generally had significantly lower levels of PLP than the control subjects, although not all the leukemia patients were below the normal range. However, a low level of a vitamin in a cancer patient does not mean that a low level contributed to the development of the disease. While some experiments in animals have indicated that vitamin B6 deprivation can contribute to the development of cancer, there is no reason to think that the children studied in the present research were deprived prior to the development of their disease. Testing of the siblings of these patients did not reveal any abnormalities, and it seems likely that the depressed levels of vitamin B6 observed in these patients are a result of inadequate nutrition resulting from cancer, rather than a contributing cause. However, it cannot be ruled out that at least some of the observed reduction in circulating vitamin B6 may result from the increased use of the vitamin by the leukemic cells themselves. Therefore, the possibility that any supplementation of the diets of these children with vitamin B6 may actually provide the cancer cells with more of what they need to grow must be considered. More must be learned about the metabolism of vitamin B6 in leukemic children before guidelines for vitamin supplementation are developed. (Consumer Summary produced by Reliance Medical Information, Inc.)

We recently reported that low molecular weight B-cell growth factor (LMW-BCGF) plus recombinant interleukin-2 (rIL-2) synergistically induced lymphokine-activated killer (LAK) activity from the bone marrow (BM) cells of children with acute lymphoblastic leukemia (ALL). The kinetics of cell growth, antigenic phenotype, and lytic activity of the generated effector cells were further analyzed in this study. BM cells from ALL patients with active disease and in complete remission (CR) were cultured with a combination of LMW-BCGF and rIL-2. Monoclonal antibodies (anti-CD3 and anti-Leu 19) and immunomagnetic beads were used to separate LAK cells into three subsets: CD3 + /Leu 19-, CD3 + /Leu 19 +, and CD3-/Leu 19+. Cytotoxicity assays with different subsets were performed versus K562, Raji, and autologous leukemic cells, using a 3-hour 51Cr release test. There was a significant cell expansion of 54-fold (mean value) for CD3+ cells and 15-fold for Leu 19+ cells in culture with LMW-BCGF plus rIL-2 for 7 to 14 days, whereas no cell expansion was observed in culture with rIL-2 alone. Although NK activity (K562) was generated from leukemic BM cells in culture with rIL-2 alone, it is only about one third of that generated in culture with rIL-2 plus LMW-BCGF. Analysis of lytic activity of cells generated in the latter cultures demonstrated that CD3 — /Leu 19+ cells expressed highest lytic activity against NK-sensitive K562 cells as well as against NK-resistant Raji cells. CD3+/Leu 19+ cells showed median cytotoxicity, and CD3+ /Leu 19— cells mediated only minimal cytotoxic activity. Also, lytic activity of CD3— /Leu 19+ cells against autologous leukemic blasts was noted in patients with active disease. Our results demonstrate that LAK activity generated from BM cells by LMW-BCGF and r-IL2 is mediated mainly by two types of Leu 19+ cells: CD3 — / Leu 19 + NK cells and CD3 + / Leu 19 + T cells. Although CD3 + T cells (both Leu 19+ and Leu 19—) mediated less anti-tumor cytotoxicity than CD3— /Leu 19+ cells, the former cells were the major expanding cell population in culture with LMW-BCGF and rIL-2. The new culture system may be effective in generation of cells with LAK activity for therapeutic use.