Malarial toxic antigens synergistically enhance insulin signalling

Hypoglycaemia is a major complication of severe malaria [(1990) Trans. Roy. Soc. Trop. Med. 84 (suppl. 2) 1–65], especially cerebral malaria, in which it is associated with increased mortality [(1990) Lancet 336, 1039–1043; (1989) Quart. J. Med. (New series) 71, 441–459]; however, the mechanisms responsible have not been fully explained. Preparations containing toxic malaria antigens (TMA) released by blood stage Plasmodium yoelii malaria parasites have been shown to induce hypoglycaemia in mice lasting at least 8 h [(1992) Clin. Exp. Immunol. (in press)]. Here we report that TMAs can act synergistically with insulin in both stimulating lipogenesis and inhibiting lipolysis in rat adipocytes in vitro, and, furthermore, that they act synergistically with insulin in the induction of hypoglycaemia in vivo.