The effects of allopurinol on immune function in normal BALB/c and SCID mice

To clarify the relationship between purine metabolism and immunity, the in vivo immunosuppressive effects of allopurinol (AL), a xanthinoxidase (XO) inhibitor, were studied using normal BALB/c and severe combined immunodeficient (SCID) mice. Following AL administration for 14 weeks (long term), a decreased immune response to ovalbumin (OVA) in the peripheral blood was observed in normal mice, which might not be only due to direct B cell suppression but also due to suppression of helper T cell function. In the SCID mice, there was a markedly late and reduced recovery of surface immunoglobulin (sIg) positive cells, which are markers for mature B lymphocytes, in the peripheral blood after AL administration. The total immunoglobulin G (IgG) titers in the AL treated group were significantly lower than in the control group 6 weeks after stem cell transfer, but increased until there was no difference in the titers between the two groups at week 14. CD4 positive helper T cells and CD8 positive T cells were slow to recover, though these gradually recovered to reach normal levels in the mature stage. These data suggest that the administration of AL may modulate B cell and T cell responses in OVA-immunized antibody formation. Furthermore, this study showed that AL could influence immune functions during the pre-natal and developmental periods and that its effects might differ according to the stages of maturity of the immune cells. (C) 2000 International Society for Immunopharmacology. Published by Elsevier Science Ltd. All rights reserved.