Predictive value of immunologic parameters and HIV RNA in relation to humoral pneumococcal polysaccharide vaccine responses in patients with HIV infection

In the study presented here immunologic markers and HIV RNA were related to specific antibody responses in 50 HIV-infected patients who had moderate immunodeficiency (median CD4+, 295) and were vaccinated with a pneumococcal polysaccharide vaccine. Low responses were associated with low IgG2 or high IgM levels (P=0.01) and good responses with high IgG4 (P=0.05) or IgG2 (P=0.07) or low beta(2) microglobulin (P=0.04) levels. A combination of IgG2 levels >1.0 g/l and IgM <1.6 g/l at baseline significantly predicted a twofold or better response in logistic regression analysis (P=0.025). Neither CD4+ lymphocyte counts nor HIV RNA levels were predictive, but it should be noted that good antibody responses were not restricted to patients with high CD4+ cell counts or low HIV RNA levels.