In vitro naïve T cell proliferation failure predicts poor post-immunization responses to neoantigen, but not recall antigens, in HIV-infection.

Immune reconstitution after HAART is incomplete, but no widely accepted method to quantify subclinical immune deficiency is available. We immunized 9 HIV-negative subjects and 29 HIV-infected patients with CD4>/=450 cells/microL and undetectable HIV RNA levels with 2 doses of diphtheria/tetanus toxoid (TT) and KLH, a presumed neoantigen. We quantified the response by lymphoproliferative assay, delayed-type hypersensitivity (DTH), and antibody titers up to 59days after enrollment. We assessed T cell proliferative capacity using anti-Vbeta3 and anti-Vbeta5 antibody stimulation, which we herein show induced predominant proliferation of naïve T cells. Subjects with detectable responses to KLH tended to exhibit greater proliferative responses to anti-Vbeta3/Vbeta5 stimulation; no such pattern was seen with response to TT. Several measures of in vitro T cell proliferative capacity correlated significantly with DTH and antibody responses to KLH, but not with TT responses; this association was independent of naïve T cell numbers. Our results indicate that naïve T cell proliferation predicts response to neo-, but not recall antigens, and suggest that it may be a meaningful reflection of in vivo immune competence in HIV-infected persons. Copyright 2010 Elsevier Inc. All rights reserved.