Wen B, et al. - Given the reciprocal influence of hepatitis C virus (HCV) and hepatitis B virus (HBV) coinfection on viral replication and host defense responses, researchers examined how HBV coinfection affects circulating T follicular helper cell (cTfh) distribution and the HCV neutralizing antibody (nAb) response. Using the HCV pseudoparticle neutralization assay, they measured HCV neutralizing antibody responses in individuals with HCV monoinfection (n=83) and HBV/HCV coinfection (n=78). They noted significantly lower HCV neutralizing antibody responses and a decreased frequency of circulating Th1-like Tfh cells (Tfh1) in the HBV coinfection group vs the HCV monoinfection group. A positive correlation of the frequency of the Tfh1 subset with HCV neutralizing antibody responses was noted in HCV monoinfection; however, under HBV/HCV coinfection, this correlation was lost. In contrast, a negative correlation was observed between the frequency of circulating Th2-like Tfh cells (Tfh2) and the HCV neutralizing antibody responses. Within cTfh cells, the Tfh2 subset composition was enhanced in HBV coinfection group, which was associated with serum HBsAg in HBV/HCV coinfection. As expected, HBV/HCV coinfection group displayed an inverse correlation between HBsAg and HCV neutralizing antibody responses. The investigators suggested that these findings may assist in assessing the immunopathogenesis of HBV/HCV coinfection.