PURINE METABOLISM IN SEVERE COMBINED IMMUNODEFICIENCY

Abstract

This chapter explains purine metabolism in severe combined immunodeficiency. In a study described in the chapter, purine metabolism in four patients with severe combined immunodeficiency (SCID) was examined. One of them had ADA deficiency, while the others had normal ADA and nucleoside phosphorylase activities. Plasma and erythrocytes were quickly separated from heparinized blood and protein-free filtrates prepared using trichloracetic acid. Lymphocytes were isolated on Ficoll–Hypaque gradients and then extracted similarly. The methods of analysis of purine and pyrimidine intermediates included ion exchange and high-pressure liquid chromatography, spectrophotometry, and spectrofluorometry. In the ADA-deficient patient, accumulations of adenosine in the plasma and adenine in the plasma, erythrocytes and urine were noted. In addition, adenine nucleotides, especially ATP, were greatly increased in erythrocytes and lymphocytes of this patient. Cyclic AMP was three times greater than normal in the ADA-deficient lymphocytes. Pyrimidine nucleotides were normal or slightly increased in erythrocytes and lymphocytes.