Repeated administration of adenoviral vectors in lungs of human CD4 transgenic mice treated with a nondepleting CD4 antibody.

The central role of CD4+ T cells in regulation of adenovirus vector-mediated immune responses has been documented previously in murine models. We analyzed the effects of a nondepleting mAb to human CD4 (CD4 mAb; Clenoliximab) on immune functions following intratracheal administration of adenoviral vectors in murine CD4-deficient mice (muCD4KO) expressing a human CD4 transgene (HuCD4 mice). Treatment of HuCD4 mice with Clenoliximab inhibited both cell-mediated and humoral immune responses to adenoviral Ags. Chronic treatment of HuCD4 mice with Clenoliximab permitted successful readministration of adenoviral vectors at least four times. The ability to readminister these vectors is associated with marked suppression of neutralizing Ab responses to viral capsid proteins. Clenoliximab also inhibited CTL and prolonged expression of the transgene. T or B cell responses to adenovirus did not emerge after the effects of a short course of Clenoliximab diminished. These data illustrate the potential utility of a nondepleting CD4 Ab in facilitating gene therapy using adenoviral vectors.