Relationship of serum immunoglobulin and IgG subclass levels to race, ethnicity and behavioral characteristics in HIV infection

Background: To determine whether demographic and behavioral factors affect immunoglobulin regulation in HIV infection, we studied injection drug users, women, and minority ethnic and racial groups with and without HIV infection. Material/Methods: A prospective cross-sectional study of ambulatory persons with or at risk for HIV infection was conducted. We enrolled 48 injection drug users (IDUs) and 43 non-IDUs seropositive for HIV and 22 seronegative at-risk individuals in the Bronx, New York City. Sixteen HIV-seronegative, non-IDUs controls were also studied. Total serum immunoglobulin levels, IgG subclasses and lymphocyte phenotypes were measured. Results: Serum IgG, IgA, IgG ₁ and IgG₃ were increased in all stages of HIV infection controlling for injection drug use, gender, race and age (p≤0.05). Serum IgM levels were significantly decreased in HIV seropositives compared to HIV seronegatives (p<0.02). Two patterns of serum immunoglobulin level elevation were found in HIV infection: 1) IgG, IgG₁ and IgG₃ levels were elevated in early and advanced HIV infection; 2) IgA, IgG₂ and IgG₄ levels were elevated only in advanced HIV infection. IgG levels were increased in Blacks compared to Caucasians with HIV infection (p=0.01). Conclusions: Serum IgG, IgG₁ and IgG₃ levels are increased in early HIV infection, while serum IgA, IgG₂, and IgG₃ levels are increased only in advanced HIV infection. In contrast, serum IgM levels are decreased in HIV infection. HIV-seropositive Blacks have higher serum IgG levels than HIV-seropositive Caucasians. Further studies are necessary to determine the mechanism(s) underlying the different patterns of immunoglobulin elevation in HIV infection.