Dampening of CD8+ T Cell Response by B Cell Depletion Therapy in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: To compare the effects of rituximab (RTX) and conventional immunosuppressants (CIs) on CD4+ T cells, Treg cells, and CD8+ T cells in antineutrophil cytoplasmic antibody-associated vasculitis (AAV). METHODS: A thorough immunophenotype analysis of CD4+, Treg, and CD8+ cells from 51 patients with AAV was performed. The production of cytokines and chemokines by CD8+ T cells stimulated in vitro was assessed using a multiplex immunoassay. The impact of AAV B cells on CD8+ T cell response was assessed using autologous and heterologous cocultures. RESULTS: CD4+ and Treg cell subsets were comparable among RTX-treated and CI-treated patients. In contrast, within the CD8+ T cell compartment, RTX, but not CIS, reduced CD45RA+CCR7- (TEMRA) cell frequency (from a median of 39% before RTX treatment to 10% after RTX treatment [P < 0.01]) and efficiently dampened cytokine/chemokine production (e.g., the median macrophage inflammatory protein 1α level was 815 pg/ml in patients treated with RTX versus 985 pg/ml in patients treated with CIs versus 970 pg/ml in those with active untreated AAV [P < 0.01]). CD8+ T cell subsets cocultured with autologous B cells produced more proinflammatory cytokines in AAV patients than in controls (e.g., for tumor necrosis factor-producing effector memory CD8+ T cells: 14% in AAV patients versus 9.2% in controls [P < 0.05]). In vitro disruption of AAV B cell-CD8+ T cell cross-talk reduced CD8+ T cell cytokine production, mirroring the reduced CD8+ response observed ex vivo after RTX treatment. CONCLUSION: The disruption of a pathogenic B cell/CD8+ T cell axis may contribute to the efficacy of RTX in AAV. Further studies are needed to determine the value of CD8+ T cell immunomonitoring in B cell-targeted therapies.

Vaccine-preventable severe morbidity and mortality caused by meningococcus and pneumococcus: A population-based study in France.

BACKGROUND: In a context of suboptimal vaccination coverage and increasing vaccine hesitancy, we aimed to study morbidity and mortality in children related to missing or incomplete meningococcal C and pneumococcal conjugate vaccines. METHODS: We conducted a prospective, observational, population-based study from 2009 to 2014 in a French administrative area that included all children from age 1 month to 16 years who died before admission or were admitted to an intensive care unit for a community-onset bacterial infection. Vaccine-preventable infection was defined as an infection with an identified serotype included in the national vaccine schedule at the time of infection and occurring in a non- or incompletely vaccinated child. Death and severe sequelae were studied at hospital discharge. Frequencies of vaccine-preventable morbidity and mortality caused by meningococcus and pneumococcus were calculated. RESULTS: Among the 124 children with serotyped meningococcal (n = 75) or pneumococcal (n = 49) severe infections included (median age 26 months), 20 (16%) died and 12 (10%) had severe sequelae. Vaccine-preventable infections accounted for 18/124 infections (15%, 95% CI 9, 22), 5/20 deaths (25%, 95% CI 9, 49), and 3/12 severe sequelae cases (25%, 95% CI 0, 54). The vaccine schedule for meningococcal C and pneumococcal conjugate vaccinations was incomplete for 71/116 (61%) children targeted by at least one of these two vaccination programs. CONCLUSIONS: Mortality and morbidity rates related to vaccine-preventable meningococcal or pneumococcal infection could be reduced by one quarter with better implementation of immunisation programs. Such information could help enhance the perception of vaccine benefits and fight vaccine hesitancy.