The rapid growth of immunology has greatly increased our understanding of disease; this growth has also generated a subject which at times appears separated from some of the basic medical sciences. Recent studies in the areas of purine metabolism and of polymorphonuclear neutrophil phago- cyte function have, however, linked immunology and clinical medicine with biochemistry. The precise defects of the inborn errors of metabolism have now provided good evidence for the importance of purine metabolism specifically the enzymes adenosine deaminase and nucleoside phosphorylase in lymphocyte...