Time course of antibody response to tetanus toxoid and pneumococcal capsular polysaccharides in patients infected with HIV

The temporal course of the humoral immune response to T-cell-dependent and T-cell-independent type 2 antigens was evaluated in HIV-infected patients. In all, 26 seropositive patients were vaccinated with tetanus toroid and 23 -valent pneumococcal vaccines; total IgG and IgG1 antibodies to tetanus tor oid (Ttox) and total IgG and IgG2 antibodies against 23 Streptococcus pneum oniae capsular antigens (PPS) were measured at baseline, 2 months, and 12 m onths after vaccination. For the Ttox, baseline levels of IgG1 (Ttox-IgG1) increased from 11.0 to 19.5 mg/L at 2 months postimmunization. Overall only 6 patients (23%) showed a significant response. At 12 months postvaccinati on, Ttox-IgG and T-tox-IgG1 were significantly lower than baseline levels ( Ttox IgG basal; 11.0 mg/L, 12 months; 0.8 mg/L, Ttox IgG1 baseline; 13.1 mg /L, Ttox IgG1 12 months; 2.4 mg/L) and in 10 patients, antibodies that fell below protective levels (0.6 mg/L). In contrast with PPS, a significant re sponse was observed at 2 and 12 months (PPS-IgG basal; 35.9 U/ml, 2 months; 151.4 U/ml, 12 months; 59.7 U/ml; PPS-IgG2 baseline 20.3 U/ml, 2 months; 1 13.2 U/ml, 12 months; 51..9 U/ml). Overall, 19 patients (76%) showed an imm une response to pneumococcal polysaccharides antigens. Immunization with th e Ttox T-cell-dependent antigen fails to elicit a significant immune respon se and may induce inhibition of antibody production in HIV-infected patient s. In contrast, immunization with a T-cell-independent type 2 antigen can c ause the pneumococcal polysaccharides to induce significant immune response in a high proportion of HIV-infected patients.