Serum IgG subclass Levels were determined using an indirect immunoenzymatic assay (ElisA) with monoclonal antibodies in 85 patients affected with definite immundoficiency (ID) syndrome and patients with infection patterns suggestive ID, but with normal Immunoglobulin class Levels and no clear evidence of ID. The ration of sex, male to female in these patients with Age range 0, 8-45 years (Mean, 6.12 yr.) were 2 to 1. This ratio was also observed in the patients with IgG subclass defect. A few of patients had low total IgG where as in a large number of patients almost normal level of total IgG were found.
More than %50 of these patients had how and/or Low normal levels in one and/or more of IgG subclass and almost suffered from an acute or chronic infection.
In the group the highest rate defect belonged to combined defect of IgG subclass (for example, IgG2-IgG4 & …..) that embraced about 40% of all defects.
In common variable ID (CVI) subclass imbalance was the rule and general decrease of all four subclasses was found. Serum IgG3 Level in the CVI was more stable than other subclasses. High percentage of patients with IgA deficiency and selective IgG deficiency which ottitis media, pnemunia and sinusitis were common in these patients had low level of IgG2, where as serum IgG1 level showed a significant increase.
Over 70% of IgG2 deficiency and about 60% of IgA deficiency were found in Ataxia telangiectasia. There was also over 40% of raised serum IgG1 level in these patients. Serum IgG subclass levels in chemotaxi defect, hyper IgE syndrome, CGD and chediac higashi were gene rally normal and/or above normal level. There was also a few cases of IgG3 and IgG4 deficiency.
In the present study, a significant percentage of defect of IgG3 (37%) and IgG4 (44%) in asthmatic patients was found, where as serum IgG1, IgG2 and IgG levels were normal and/or above. There were low percentage of IgG3 and IgG4 defect (15%) in the atopic patients, but a significant increase in the serum IgG4 level was observed. The incidence of subclass deficiencies was strikingly high (one patient in four) in a number of infection-prone patients without overt ID syndrome.
Finally, in the present study, no clear correlation between subclass levels and the occurrence of infection was found since there were children with overt IgG subclass deficiency but with no susceptibility to in fection.