Evaluation of serum levels of IgG subclasses and anti-ribosyl-ribitolphosphate IgG and IgG2 in children with Haemophilus influenzae b meningitis

In 40 children with Haemophilus influenzae b (Hib) meningitis, we determine d serum levels (mg/dl) of IgG subclasses using the radial immunodiffusion m ethod; 67.8 per cent of these children were less than 24 months old. In 14 children of the sample we measured serum IgG and IgG2 anti-ribosyl-ribitolp hosphate (anti-PRP) (by enzyme-linked immunosorbent assay, ELISA) in the ac ute and convalescent phases of the disease, Lower IgG2 levels than those of the control group were obtained in all age ranges: 3-12 months, 1-2 years (p < 0.01), and 2-5 years (p < 0.002), IgG4 was also present in lower level s in patients of ail age ranges (p < 0.05, p < 0.001, and p < 0.01 respecti vely), Serum levels of IgG anti-PRP and IgG2 anti-PRP measured were very lo w in the acute phase of the disease in all age ranges and there was no nota ble increase in levels during the convalescent phase of the disease. This r esult indicates that children less than 24 months old do not produce suffic ient levels of IgG and IgG2 anti-PRP even after Hib meningitis.