Chronic HCV infection, HCV/HIV coinfection and older age are independently associated with na ve CD4+CD31+lymphopenia

Abstract Background Chronic Hepatitis C virus (HCV), HCV/HIV and aging are known to predispose to impaired immunity to vaccines, new infections and cancers. Naïve CD4+CD31+ lymphopenia is exhibited in all three conditions, and may be one contributor to impaired immunity. Whether age and chronic HCV or HCV/HIV infection status independently impact naïve CD4+CD31+ lymphopenia in older chronic infected individuals has not been described. Methods We enumerated naïve CD4+ and CD4+CD31+ absolute counts in chronic HCV (n=28) and ART controlled HCV/HIV (n=13) participants spanning a broad age range (HCV 27–87, HCV/HIV 27–70), and age distribution-matched uninfected controls (n=18, age 24–88) by flow cytometry. Kruskal-Wallis test (by SPSS) was used to compare variables across groups, and Spearmans rho test was used to evaluate correlations within individual groups. Results Naive CD4+ and CD4+CD31+ counts differed across groups (HCV, HCV/HIV and control groups, p=0.01 and p=0.03), while age did not differ across groups. Lower naive CD4+ and CD4+CD31+ counts were observed in the HCV infected participants compared to the controls (p=0.007 and p=0.01). Within the HCV group age negatively correlated with the naive CD4+ and CD4+CD31+ counts (r= −0.51 p=0.006, and r= −0.64 p<0.001). Conclusions Both the state of infection (HCV or ART controlled HCV/HIV) and age independently impact naive CD4+ and CD4+CD31+ counts. Further studies are needed to understand how the mechanisms resulting in CD4+CD31+ lymphopenia during infection and ageing differ, and whether there is immune restoration following HCV DAA therapy.