Immunoglobulin G (IgG) subclass distribution and IgG1 avidity of antibodies in human immunodeficiency virus-infected individuals after revaccination with tetanus toxoid

In human immunodeficiency virus (HIV)-infected individuals the amount of antibodies formed after vaccination with T-cell-dependent recall antigens such as tetanus toroid is proportional to the peripheral blood CD4(+) T-lymphocyte counts. To investigate whether the immunoglobulin G (IgG) subclass distribution and avidity of the antibodies produced after vaccination are affected as well, we gave 13 HIV-infected adults with low CD4(+) T-lymphocyte counts (<200 x 10(6)/liter; group I), 11 EIN-infected adults with intermediate CD4(+) T-lymphocyte counts (greater than or equal to 200 x 10(6)/liter; group II), and 5 healthy controls booster immunizations with tetanus toroid. The prevaccination antibody concentrations against tetanus toroid were similar in the HIV-infected and healthy adults. After vaccination the total IgG and the IgG1 anti-tetanus toroid antibody concentrations were significantly lower in group I than in group II and the controls. The avidity of the IgG1 anti-tetanus toroid antibodies formed by HIV-infected adults was within the range for healthy controls, irrespective of their CD4(+) T-lymphocyte counts.