T cell activation and human immunodeficiency virus replication after influenza immunization of infected children

Abstract

Background: T cell activation plays a major role in the ability of HIV to remain latent or to establish a productive infection. It has been hypothesized that vaccination-mediated immune stimulation can activate T cells and enhance HIV replication. Our study was designed to determine whether influenza immunization would induce T cell activation and increase HIV burdens in HIV-infected children.

Methods: Blood samples from 16 HIV-infected children ages 6 months to 14 years were obtained immediately before and 2 and 6 to 8 weeks after the administration of influenza vaccine. The percentage of activated (CD25+) T cells was determined by flow cytometry, and HIV viral load was measured by quantitative cultures of peripheral blood mononuclear cells and plasma HIV RNA.

Results: The administration of influenza vaccine was associated with significant increases in HIV viral load in 5 of 16 children evaluated. These increases in HIV burden were transient, and in four of five patients the plasma HIV RNA copy number returned to baseline 6 to 8 weeks after immunization. There was no correlation between the patient's immunologic or clinical category according to the CDC classification and either the initial viral load or the likelihood of having a significant increase after immunization. Four of the five patients who experienced increases in viral load after influenza immunization were not receiving antiretroviral therapy.

Conclusions: Our results emphasize the need for additional studies that examine the effect of routine immunizations on T cell activation and HIV replication in HIV-infected children.