CD4+ and CD8+ CD28(null) T Cells Are Cytotoxic to Autologous Muscle Cells in Patients With Polymyositis.
Arthritis Rheumatol 2017;
68:2016-26. [PMID:
26895511 DOI:
10.1002/art.39650]
[Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 02/16/2016] [Indexed: 12/12/2022]
Abstract
OBJECTIVE
Inflammatory T cell infiltrates in the skeletal muscle tissue of patients with polymyositis are dominated by CD28-negative effector (CD28(null) ) T cells of both the CD4 and CD8 lineage. These cells are potentially cytotoxic, and the aim of the present study was to develop a fully autologous cell culture system in which to investigate the functional contribution of such CD28(null) T cells to myotoxicity.
METHODS
In vitro cocultures of autologous skeletal muscle cells and T cell subsets obtained from 5 polymyositis patients were performed. Myotoxicity of T cells was quantified by calcein release and flow cytometric analyses. T cell degranulation was blocked with concanamycin A. Specific blocking of perforin, cytokines, and HLA was performed using antibodies.
RESULTS
Both CD4+CD28(null) and CD8+CD28(null) T cells induced more muscle cell death than did their CD28+ counterparts. Differentiated muscle cells (myotubes) were more sensitive to T cell-mediated cell death than were their precursors (myoblasts). Both CD8+ and CD4+ CD28(null) T cells displayed perforin polarization toward muscle cells and secreted higher levels of granzyme B and interferon-γ (IFNγ) in coculture than did CD28+ T cells. The myotoxic effects of CD28(null) T cells were reduced upon the blocking of perforin, cytokines, and HLA. Addition of IFNγ or tumor necrosis factor did not induce skeletal muscle cell death in the absence of T cells; however, it did up-regulate HLA expression on muscle cells.
CONCLUSION
Myotoxicity of CD4+ and CD8+ CD28(null) T cells is mediated by directed perforin-dependent killing and can be further influenced by IFNγ-induced HLA expression on muscle cells. The data suggest that CD28(null) T cells are key effector cells that contribute to the muscle cell damage in polymyositis.
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