Interleukin-7 levels may predict virological response in advanced HIV-1-infected patients receiving lopinavir/ritonavir-based therapy

Objectives. To examine the relationship between levels of the T-cell regulatory cytokine interleukin-7 (IL-7) and CD4 cell counts during immune reconstitution and to assess its prognostic value in advanced HIV-1-infected patients receiving lopinavir/ritonavir-based therapy. Methods. Thirty-six HIV-1-infected adults who completed 48 weeks of follow-up visits were included in this prospective study. Patients having failed two or more antiretroviral therapy regimens were treated with lopinavir/ritonavir-based therapy. An enzyme-linked immunosorbent assay was used to determine IL-7 plasma levels, flow cytometry was used to analyse cell surface antigens, and polymerase chain reaction was used to quantify plasma HIV-1. Results. Pretreatment IL-7 levels were elevated in all patients (mean 11.0 pg/mL) and were negatively correlated with CD4 cell counts and age (r = -0.59, P<0.001 and r = -0.57, P<0.001, respectively). During the course of treatment, IL-7 levels decreased by 34% while CD4 cell numbers progressively increased by 88%. Multivariate regression analysis showed that only pretreatment IL-7 levels predicted viral load at 48 weeks when controlling for baseline CD4 cell counts, viral load and patient demographics. Conclusions. These findings are consistent with regulation of T-cell recovery by IL-7, and suggest that IL-7 measurements might be used to predict virological response.