The importance of B-cells and ecto-5'nucleotidase in Mycoplasma fermentans infection and the relevance to rheumatoid arthritis.
The aim of this work was to discover if Mycoplasma fermentans, which is known to infect B cells, could be the cause of the raised ecto-5'-nucleotidase observed in the synovial fluid of rheumatoid arthritis patients. The ecto-5'-nucleotidase activity in the patients' serum has been shown to correlate with the erythrocyte sedimentation rate and DNA from the mycoplasma has been found in the synovial fluid. B lymphoblastoid cell lines were exposed to 16 strains of Mycoplasma fermentans and their ecto-5'-nucleotidase, CD73, was measured both biochemically and by mouse antibodies to human ecto 5'-nucleotidase using the fluorescence activated cell sorter. The type strain, PG 18, did not grow with the B cells. Some of the mycoplasma strains (9/15) increased the cellular ecto-5'-nucleotidase activity from twice to 17 fold, and usually showed 5'-nucleotidase activity themselves. At least one strain, M106, induced human 5'-nucleotidase on the normally 5'-nucleotidase negative Daudi and Raji Burkitt's lymphoma cell lines, and increased sevenfold the 5'-nucleotidase on the monocyte/macrophage cell line THP-1. Growing the cells in aged medium increased the level of mycoplasma infection. This mycoplasma-induced enzyme showed a conformational change and an increase in activity with a glycosylation change involving mannose groups. The other group of strains, mostly of respiratory or cell culture origin, usually did not have any 5'-nucleotidase of their own and decreased the B-cell enzyme activity by about half. Electron microscopy and flow cytometry showed that the strain M106 was filamentous and could be found inside the B-cells. The 5'-nucleotidase-inducing strains of M. fermentans may be important in the aetiology of rheumatoid arthritis.
Department of Basic Medical Sciences, St. George's University of London, London, UK. sjohnson@sgul.ac.uk
Sheena M
SM
Johnson
D015720:5'-Nucleotidase / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D001402:B-Lymphocytes / Q000276:immunology / Q000382:microbiology* / Q000648:ultrastructure; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D008854:Microscopy, Electron; D009175:Mycoplasma Infections / Q000150:complications* / Q000201:enzymology / Q000276:immunology; D016858:Mycoplasma fermentans / Q000145:classification / Q000302:isolation & purification* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured
D015720:5'-Nucleotidase