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.

Human papillomavirus immunization is associated with increased expression of different innate immune regulatory receptors.

Human papillomavirus (HPV) is able to inhibit the secretion of gamma interferon (IFN-γ) and the expression of some immune innate cell receptors. Immunoglobulin-like transcript 2 (ILT2) is a regulatory receptor that seems to participate in the pathogenesis of viral infections. We have studied the expression and function of ILT2 and the expression of other NK cell receptors in 23 healthy women before and after immunization with the quadrivalent HPV (type 6/11/16/18) vaccine (Gardasil). Receptor expression was analyzed by flow cytometry in freshly isolated peripheral blood mononuclear cells as well as after in vitro stimulation with the quadrivalent HPV (type 6/11/16/18) vaccine. In addition, the regulatory function of ILT2 on cell proliferation and IFN-γ production was analyzed. We found a significant increase in the expression of ILT2 by NK and CD3(+) CD56(+) lymphocytes and monocytes after quadrivalent HPV (type 6/11/16/18) vaccine immunization. In addition, the in vitro stimulation with the quadrivalent HPV (type 6/11/16/18) vaccine also increased the proportion of CD3(-) CD56(+) ILT2(+) NK cells. Although the inhibitory function of ILT2 on cell proliferation was enhanced after HPV immunization, the in vitro engagement of this receptor did not affect the synthesis of IFN-γ induced by HPV. Finally, a significant increase in the expression of NKG2D, NKp30, and NKp46 by NK and CD3(+) CD56(+) lymphocytes was detected after quadrivalent HPV (type 6/11/16/18) vaccine immunization. Our data indicate that HPV immunization is associated with significant changes in the expression and function of different innate immune receptors, including ILT2, which may participate in the protective effect of HPV vaccines.