Characterization of the DNA-synthesizing cells in rheumatoid synovial tissue

DNA-synthesizing cells from the rheumatoid arthritis synovial tissue of 7 patients and from 5 patients with traumatic and degenerative joint lesions were studied by incubating fresh synovial tissue samples with tritiated thymidine. Labelled cells were identified using autoradiography. The tissue sections were stained with methyl green pyronine. It was found that 0.66% (range 0.38-1.4) of the cells were labelled with 3H-thymidine whereas in control materials the percentage was 0.17 (range 0-0.38). Approximately half of the labelled subsynovial cells in rheumatoid patients (range 37-67%) were small lymphocytes, according to morphological criteria. About one-tenth of the labelled cells (range 0-17%) looked like medium-sized lymphocytes, while the rest had the characteristics of fibroblasts or were unidentifiable.