Mucosal and plasma IgA from HIV-exposed seronegative individuals neutralize a primary HIV-1 isolate

Objective: To characterize functional properties of HIV-specific IgA in sam ples representing both systemic and mucosal compartments of HIV-1 highly ex posed persistently seronegative (HEPS) individuals. Methods: IgA was purified from plasma and mucosal samples from HEPS individ uals and tested for the ability to neutralize infection of peripheral blood mononuclear cells (PBMC) by a non-syncytium inducing HIV-1 (clade B) prima ry isolate. None of these individuals had measurable HIV-l-specific IgG. Results: HIV-1-specific neutralizing activity of the purified IgA from plas ma (n = 15), saliva (n = 15) and cervicovaginal fluid (CVF) (n = 14) were f ound in the majority of samples (73, 73 and 79%, respectively). In contrast , plasma, saliva and CVF samples of low-risk, uninfected HIV-seronegative i ndividuals lacked neutralizing IgA, with the exception of two out of 34 (6% ) saliva samples. Conclusion: Mucosal and plasma IgA from HEPS individuals can neutralize HIV -1 Introduction infection. (C) 2000 Lippincott Williams & Wilkins.