Increased Numbers of CD4⁺CD25⁺ and CD8⁺CD25⁺ T-Cells in Peripheral Blood of Patients with Rheumatoid Arthritis with Parvovirus B19 Infection

Aim: To investigate T-cell subpopulations in peripheral blood of human parvovirus B19 DNA-positive (B19+) and-negative (B19-) patients with rheumatoid arthritis (RA) and healthy persons. Patients and Methods: Blood samples were collected from 115 patients with RA and 47 healthy volunteers; 27 patients with RA and nine controls were B19⁺. Cluster of differentiation (CD) 4, 8, 25 and 45RA were analyzed on blood cells. CD25 expression on CD4⁺CD45RA⁺, CD4⁺CD45RA-, CD8+CD45RA+, CD8+CD45RA- subsets were analyzed by flow cytometry. Results: The percentage of CD25low and CD25hi cells was increased on CD4⁺CD45RA⁺, CD4⁺CD45RA^-T-cells and the percentage of CD25+ cells was increased on CD8⁺CD45RA⁺, CD8⁺CD45RA-T-cells of B19+ patients with RA in comparison with B19^- patients and controls. Conclusion: Raised levels of CD4 and CD8 regulatory T^-cells in B19⁺ RA patients could cause downregulation of antiviral clearance mechanisms and lead to activation of persistent human parvovirus B19 infection in patients with RA.