Decreased blood levels of B lymphocytes and NK cells in patients with systemic lupus erythematosus (SLE) infected with papillomavirus (HPV)

Patients with systemic lupus erythematosus (SLE) show an enhanced risk to develop human papillomavirus (HPV) infection, and aggressive forms of this condition are seen in these patients. The aim of this study was to assess the possible relationship among HPV infection, immunosuppressive therapy and levels of leukocyte subsets in patients with SLE. The following individuals were included in the study: (1) SLE patients under immunosuppressive therapy and with lesions caused by HPV (n = 16); (2) SLE patients under immunosuppressive therapy and no evidence of HPV infection (n = 20); (3) untreated SLE patients with no evidence of HPV infection (n = 7), and; (4) healthy female subjects without evidence of HPV infection (n = 10). Peripheral blood was obtained and the percentages of different lymphocyte subsets were determined by flow cytometry, with the use of the following monoclonal antibodies: CD3, CD4, CD8, CD16, CD19, CD20, CD22, CD56, and CD335 (NKp46). We found that SLE patients under immunosuppressive therapy and with lesions caused by HPV showed significantly lower levels of B lymphocytes and NK cells compared to other groups. In contrast, SLE patients receiving immunosuppressive drugs and with no evidence of HPV infection showed similar levels of B and NK cells than healthy controls. Those patients receiving mycophenolate mofetil (MMF) had a diminished number of B cells, and a positive correlation was detected between the dose of MMF and the number of HPV skin lesions. Our data suggest that therapy of SLE patients with MMF is associated with diminished levels of B and NK cells and an enhanced risk for HPV infection.