B-cell activation and differentiation by HIV-1 antigens among volunteers vaccinated with VaxSyn HIV-1

The generation of memory B cells in response to vaccination with a baculovirus-derived recombinant gp160 candidate AIDS vaccine, VaxSyn HIV-1, was investigated in 12 healthy human volunteers who were immunized with VaxSyn HIV-1, hepatitis B vaccine, or alum adjuvant alone on days 1, 28, 180, and 540. Peripheral blood mononuclear cells were collected pre- and post-immunization and cultured unstimulated or with pokeweed mitogen (PWM), VaxSyn HIV-1 (rgp160), or HIV-1 lysate (iHIV-1) for 7 days before polyclonal and HIV-1-specific IgG production in culture supernatants (SNs) were measured. No differences were seen in the spontaneous or PWM-induced IgG production in SN from vaccinees and controls. Only vaccinee SN contained higher-than-normal levels of polyclonal IgG after stimulation with either rgp160 or iHIV-1, especially after the second and third booster immunizations on days 180 and 540, respectively. There were also contemporaneous increases in HIV-1-specific antibody in SN of all vaccinees, albeit at different time points throughout the study. We conclude that VaxSyn HIV-1 induces antigen-specific B-cell responses with the generation of memory B cells in vivo that can be reactivated in vitro to deliver an anamnestic response.