Long-term resistance to HIV infection in vertical HIV infection: cytokine production, HIV isolation, and HIV phenotype define long-term resistant hosts

We analyzed immunologic (CD4 and CD8 slopes; interferon-γ, interleukin-2, interleukin-10, and chemokines production; concentration of IgE; β2-microglobulin) and virologic (p24; HIV isolability and phenotype; plasma viremia) parameters in HIV vertically infected children ≤ 8 years of age without disease progression or mild symptoms and an absolute CD4+ count ≤ 500/μl with CD4+ percentage ≤ 25%. The results were compared to those of two control groups: (1) slow progressors, children ≤ 8 years of age with moderate symptomatology and/or moderate CD4 depletion, and (2) progressors, children ≤ 8 years of age with severe clinical disease and/or severe CD4 depletion. Pediatric long-term resistant hosts were characterized by higher production of interleukin-2 and interferon-γ and lower production of interleukin-10, normal concentration of IgE, HIV isolates with a non-syncytium-inducing phenotype, and lower plasma viremia. This condition was not associated with the concentration of β2-microglobulin, p24, and chemokines, or with HIV isolability. The IL-10/IL-2 ratio best correlated with both CD4 counts and disease progression. Thus, vertically infected children showing resistance to disease progression are immunologically and virologically distinct from those in whom progressive HIV infection is observed.