ABSTRACT This study aims at determining the effect of the ABO blood groups on the level of immunoglobulin classes in patients infected with HIV-1. One hundred and fifty three (153) confirmed HIV-1 positive subjects were enrolled in the study. These comprise of 62 (40.5%) males and 91 (59.5%) females. Sex and age-matched HIV-negative control were also recruited. The subjects comprise of adults aged 18 - 55 years with 36 years as the mean age. The study was conducted at the CDC-UNTH HIV clinic ...