metabolism in relation to lymphocyte function, for instance, has opened up new possibilities for immunomodulation and leukaemia chemotherapy, with eventual conse­ quences for other types of cancer. At previous meetings there have been pointers implicating purine metabolism in relation to normal cardiac and skeletal muscle function. During the present meeting much new data on both issues have been re­ ported which indicate clear differences in the pathways of ATP metabo­ lism. The widening of the field of interest is also illustrated by the recent work on infectious disease: exploitation of the differences in purine metabolic pathways in certain parasites compared with those in human cells has resulted in new rationales for therapy being devel­ oped.