Key differences in B cell activation patterns and immune correlates among treated HIV-infected patients versus healthy controls following influenza vaccination

Background: There is increasing recognition of the role of B cell dysfunction in HIV pathogenesis, but little is known about how these perturbations may influence responses to vaccinations. Methods: Healthy controls (n = 16) and antiretroviral therapy (ART)-treated aviremic HIV-infected subjects (n = 26) receiving standard-of-care annual influenza vaccinations were enrolled in the present study. Total bacterial 16 S rDNA levels were assessed by quantitative polymerase chain reactions in plasma. Serologic responses were characterized by ELISA, hemagglutination inhibition assay (HI), and microneutralization, and cell-mediated responses were assessed by ELISPOT (antigen-specific IgG+ antibody-secreting cells (ASCs)) and flow cytometry at pre-vaccination (D0), day 7-10 (D7) and day 14-21 (D14) post-vaccination. Results: Decreased peripheral CD4+ T cell absolute counts and increased frequencies of cycling and apoptotic B cells were found at baseline in HIV-infected subjects relative to healthy controls. In healthy controls, post-vaccination neutralizing activities were related to the frequencies of vaccine-mediated apoptosis and cycling of B cells, but not to CD4+ T cell counts. In patients, both baseline and post-vaccination neutralizing activities were directly correlated with plasma level of bacterial 16S rDNA. However, overall vaccine responses including antibody titers and fold changes were comparable or greater in HIV-infected subjects relative to healthy controls. Conclusion: B cell function correlates with measures of recall humoral immunity in response to seasonal influenza vaccination in healthy controls but not in ART-treated patients.