(4), e70218.
AIM: We aimed to assess the populations of lymphocytes: NK cells, NKT cells and T cells, and the expression of the immunoregulatory receptor CD244 (2B4) by each population in rheumatoid arthritis (RA) patients with concomitant hepatitis C virus (HCV) infection.
METHODS: Lymphocyte phenotyping for NK cells (CD3-CD56+), NKT cells (CD3 + CD56+), and T cells (CD3 + CD56-) was analyzed by flow cytometry in patients with HCV positive RA (n = 21), HCV negative RA (n = 20) and controls (n = 11). Surface expression of CD244 by each lymphocyte population was quantified as mean fluorescence intensity and frequency of CD244 expressing cells.
RESULTS: Patients with and without concomitant HCV displayed comparable numbers of NK, NKT, and T cells to controls. We observed that the expression intensity of CD244 was downregulated by the lymphocyte populations in HCV positive and HCV negative RA compared to controls (NK CD244 p < 0.001, NKT CD244 p = 0.047, T CD244 p < 0.001). Yet, the downregulation was more profound in HCV positive RA, as CD244 expression by NK cells and T cells was decreased in HCV positive in relation to negative RA (p < 0.001 and p = 0.003, respectively). In addition, the frequency of CD244-expressing NK and NKT cells in HCV positive RA was lower compared to HCV negative RA and controls (p < 0.001 and p = 0.001, respectively). T cell CD244 expression was significant for discriminating clinically active from less active RA with and without HCV (n = 41), area under the curve = 0.717 (95% CI 0.560-0.873, p = 0.007).
CONCLUSION: Our findings reveal a distinct expression pattern of CD244 by lymphocytes of RA with HCV infection.
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