T lymphocyte subsets and immunoglobulin and complement levels are associated with the infection status of patients with antineutrophil cytoplasmic antibody-associated vasculitis

Abstract

Background: Infection is the leading cause of death in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The aim of this study was to characterize the immunological features of infectious events occurring in patients with newly diagnosed AAV and to identify possible risk factors associated with infection.

Methods: The T lymphocyte subsets, immunoglobulin, and complement levels of the groups were compared between infected group and the noninfected group. Further, regression analysis was conducted to determine the association of each variable with the risk of infection.

Results: 280 patients with newly diagnosed AAV were enrolled. The average levels of CD3⁺ T cells (720.0 vs. 920.5, P < 0.001), CD3⁺CD4⁺ T cells (392.0 vs. 547.0, P < 0.001), and CD3⁺CD8⁺ T cells (248.0 vs. 335.0, P = 0.001), serum IgG (11.66 g/L vs. 13.59 g/L, P = 0.002), IgA (1.70 g/L vs. 2.44 g/L, P < 0.001), C3 (1.03 g/L vs. 1.09 g/L, P = 0.015), and C4 (0.24 g/L vs. 0.27 g/L, P < 0.001) were significantly lower in the infected group than in the noninfected group. The levels of CD3⁺CD4⁺ T cells (adjusted OR 0.997, P = 0.018), IgG (adjusted OR 0.804, P = 0.004), and C4 (adjusted OR 0.001, P = 0.013) were found independently associated with infection.

Conclusions: Patients of infected AAV and those without infection differ in T lymphocyte subsets and immunoglobulin and complement levels. Furthermore, CD3⁺CD4⁺ T cells counts and serum IgG and C4 levels were independent risk factors with infection in patients with newly diagnosed AAV.

Keywords: ANCA-associated vasculitis; Complement; Immunoglobulin; Infection; T lymphocyte subset.