Anti-alpha interferon immunization: safety and immunogenicity in asymptomatic HIV positive patients at high risk of disease progression.

ABSTRACT

A randomized, placebo-controlled trial was designed to evaluate safety and immunogenicity of an anti-cytokine vaccine in high risk HIV-positive patients. This strategy was aimed to modulate the impaired cytokine regulation in AIDS. Twelve asymptomatic patients on antiretroviral therapy for at least 1 year and with CD4 cell counts between 100-300/mm3 were randomized to receive adjuvanted formol-inactivated interferon alpha-2a (IFN alpha) and continue the current antiretroviral treatment, whatever it was, or to receive the adjuvant alone and the current antiretroviral treatment. All patients received 4 i.m. injections monthly, followed by booster injections every 3 months. Clinical status, immunology and virology were monitored. Immune response to vaccination was evaluated in term of antibody detection (ELISA) and serum anti-IFN alpha neutralizing capacity. Only local discomfort and transient fever were reported. All vaccines except one showed increased levels of anti-IFN alpha Abs and developed serum IFN alpha neutralizing capacity. Viral load did not increase in vaccinees while it remained unchanged or even increased in placebo-treated patients. None of them showed HIV-related symptoms and all had their CD4 cell counts stabilized over 18 months, whereas 2 placebo-treated patients developed full-blow AIDS. In conclusion, anti-IFN alpha vaccine was safe and immunogenic. Stable clinical and immunological status over 18 months was observed in vaccinees coupled to increased serum IFN alpha neutralizing capacity.