Immunoglobulin allotypes and genetic susceptibility to invasive Haemophilus influenzae type b and Staphylococcus aureus infections in South African children

Objective. The purpose of this study was to determine whether the G2m(n), G1m(f) and Km(3) immunoglobulin allotypes have any association with susceptibility to invasive Haemophilus influenzae type b (Hib) and Staphylococcus aureus (S. aureus) infections in children. Methods. Direct enzyme-linked immunosorbent assays with commercially available monoclonal antibodies were established to quantitate G2m(n) and G1m(f) allotypes. A qualitative enzyme-linked immunosorbent assay with polyclonal rabbit anti-Km(3) antibody was established for Km(3) determination. Results. The G2m(n) marker occurred in 34.4% of the mixed ancestry population and 2.9% of the Black population. There was a significantly decreased frequency of the G2m(n) allotype in mixed ancestry children with Hib meningitis (8.5%) and Hib osteomyelitis/septic arthritis and a decreased frequency of Km(3) in black and mixed ancestry children with Hib meningitis. The frequency of G2m(n), G1m(f) and Km(3) allotypes in patients with S. aureus osteomyelitis/septic arthritis were not significantly different from normal population frequency. Conclusions. This study shows a clear association between the absence of the G2m(n) allotype in mixed ancestry children and susceptibility to invasive infections caused by H. influenzae and an association between the absence of Km(3) and Hib meningitis in both black and mixed ancestry children.