Immune Recovery under Highly Active Antiretroviral Therapy Is Associated with Restoration of Lymphocyte Proliferation and Interferon‐γ Production in the Presence ofToxoplasma gondiiAntigens

The in vitro lymphocyte proliferative response (LPR) and interferon (IFN)-gamma production in the presence of Toxoplasma antigen were evaluated in 97 human immunodeficiency virus (HIV)-1-infected patients with CD4 cell counts of <100 cells/microL (group 1), currently >300 cells/microL but previously <100 cells/microL (group 2), or always >300 cells/microL (group 3) and in 28 non-HIV-infected blood donors (group 4), all seropositive to Toxoplasma. In group 2, 81% of patients had a positive LPR, versus 20% in group 1 (P<10(-3)). IFN-gamma production was greater in group 2 than in group 1 (922 vs. 0 Deltapg/mL; P=10(-4)). Multivariate analysis found a significant association between a positive LPR to Toxoplasma antigen and a CD4 count >300 cells/microL (odds ratio [OR], 16.3; 95% confidence interval [CI], 5.3-50.2) and anti-Toxoplasma IgG titer >150 IU/mL (OR, 5; 95% CI, 1.6-15.2). Immune reconstitution under highly active antiretroviral therapy was associated with a restoration of immune responses against Toxoplasma.