title: Altered T lymphocyte signaling in rheumatoid arthritis.
abstract: Synovial and peripheral blood T cells from patients with rheumatoid arthritis are functionally deficient. This may be secondary to their reduced cytokine (e.g. interleukin-2) synthesis. We have investigated the possibility of an alteration in pathways common to interleukin-2 production and proliferation in peripheral blood T cells from patients with active rheumatoid arthritis. Intracellular calcium levels ([Ca2+]i) were analyzed by flow cytometric methods in Indo1-loaded T cells. These were purified by negative selection from patients or age/sex-matched controls, and stimulated with phytohemagglutinin-P or anti-CD3. Rheumatoid [Ca2+]i responses to both stimuli were reduced (p < 0.005). Patient cell samples included a larger proportion of non-responding cells, but even in the responsive population the magnitude of the response in rheumatoid cells was impaired compared with those in normal cell samples (p < 0.0001) for both stimuli. Proliferation responses were also impaired (p < 0.005), and there was a positive correlation between the paired [Ca2+]i elevation and proliferative responses for both stimuli. CD2 and CD3 expression were normal, and the proportions of CD4, CD8 and CD45RO and CD45RA subsets were also unaffected by disease. Thus a signaling defect downstream of CD2 or CD3 surface molecules may contribute to functional deficiencies in rheumatoid T lymphocytes. This effect is not due to non-steroidal anti-inflammatory drugs which some patients were taking. We have demonstrated similar alterations in [Ca2+]i responses and proliferation in a smaller study of patients with inflammatory bowel disease, indicating that such changes might be present in other chronic inflammatory states.
authors.affiliation: Department of Rheumatology, University of Birmingham, GB.
authors.forename: M E
authors.initials: ME
authors.lastname: Allen
authors.forename: S P
authors.initials: SP
authors.lastname: Young
authors.forename: R H
authors.initials: RH
authors.lastname: Michell
authors.forename: P A
authors.initials: PA
authors.lastname: Bacon
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000473:pathology; D002118:Calcium / Q000032:analysis; D002455:Cell Division; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D008297:Male; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D015703:Antigens, CD; D007376:Interleukin-2; D002118:Calcium