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ICOS and B7 costimulatory molecule expression identifies activated cellular subsets in rheumatoid arthritis
Author(s) -
Ruth Jeffrey H.,
Rottman James B.,
Kingsbury Gillian A.,
Coyle Anthony J.,
Haines G. Kenneth,
Pope Richard M.,
Koch Alisa E.
Publication year - 2007
Publication title -
cytometry part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.316
H-Index - 90
eISSN - 1552-4930
pISSN - 1552-4922
DOI - 10.1002/cyto.a.20383
Subject(s) - cd14 , flow cytometry , immunology , t cell , antigen , proinflammatory cytokine , population , lymphocyte , monocyte , t lymphocyte , inflammation , synovial fluid , antigen presenting cell , biology , microbiology and biotechnology , chemistry , immune system , medicine , pathology , alternative medicine , environmental health , osteoarthritis
To better define important cell subsets expressing activation markers in rheumatoid arthritis (RA), we compared selective lymphocyte and monocyte B7H1, B7H2, B7RP.1, B7RP.2, and inducible costimulatory molecule (ICOS) expression from normal peripheral blood (NL PB), RA PB, and RA synovial fluid (SF) by multicolor flow cytometry and immunohistochemistry. RA SF memory lymphocytes expressed B7RP.1 and B7RP.2, suggesting that T‐cells may function as antigen presenting cells (APCs) in RA joints. We found similar results for ICOS expression. RA SF CD14+ monocytes also expressed B7RP.1 (an ICOS ligand) and the homologous ligand B7RP.2, identifying monocytes as potential mediators of antigen processing and lymphocyte activation in RA. Furthermore, we found an increased population of RA SF CD14+ monocytes expressing B7H1 and B7H2. [The FACS analysis was supported by immunohistochemistry, showing intense lymphocyte and APC (macrophages with dendritic morphology) ICOS staining in RA synovial tissue (ST). Overall, these results define elevated populations of memoryT‐lymphocytes expressing proinflammatory B7 molecules in RA SF that either stimulate T cells through ICOS (via ICOS ligands B7RP.1 and B7RP.2), or down‐regulate RA ST T‐lymphocytes through B7H1 and B7H2.] Therefore, in the same joint, there may exist positive and negative influences on the inflammatory response, and perhaps, the negative signals dominate as joint inflammation resolves. © 2007 International Society for Analytical Cytology