Degradation of Thymidine to Thymine by Rheumatoid Arthritis Synovial Tissue Eluate

Abstract

A study was made of the effect of [human] rheumatoid synovial tissue eluate on phytohemagglutinin (PHA) stimulation of peripheral blood lymphocytes. Rheumatoid synovial tissue eluate caused marked inhibition of 3H-thymidine incorporation by lymphocytes stimulated with PHA. Synovial tissue from traumatic joints had no effect. The inhibitor was a heat-sensitive and nondialyzable substance. The inhibitory effect on PHA stimulation was diminished by thymine. In TLC it showed the capacity to convert thymidine to thymine. Because thymine is not incorporated by DNA-synthesizing cells, this report explains why negative results are obtained when lymphocytes are stimulated by rheumatoid synovial tissue using 3H-thymidine incorporation as an indicator of lymphocyte activation.