Expression of costimulatory molecule CD40L in T cell subpopulation in RA patients

Objective To investigate the relationship between abnormal expression of costimulatory molecule CD40L in T cell subpopulation and the immune disfunction in patients with rheumatoid arthritis (RA). Methods In 46 RA patients and 20 healthy controls, CD3, CD4, CD8, and CD40L on the surface of T cells were labeled and determined by immunofluorescence and flow cytometry, respectively; IgG, IgA, and IgM in serum were determined by rate nephelometry. Results As compared with controls, the CD3 + CD4 + T cells in RA patients were significantly increased (P 0.05) but the CD3 + CD8 + T cells were significantly decreased (P 0.05). The CD40L expression level in CD4 +T cells and CD8 +T cells in RA patients were both significant higher that in healthy controls (P 0.05) while the levels of IgG, IgA, and IgM in serum of RA patients were significant higher than those in healthy controls (P 0.05). Conclusion As a second signal, increased CD40L expression in T cells interacts with CD40 in B cells, activates the T and B cells, promotes the hyperfunction of cellular immunity, and induces the cellular proliferation of B cells in RA patients. As a result, a lot of immunoglobulin are produced. CD40-CD40L pathway plays an important role in immune disfunction of RA patients.