IgG subclasses in nonallergic children with chronic chest symptoms.

Immunoglobulin and IgG subclass measurements were made on sera from 37 children thought to have asthma whose chronic chest symptoms were unexplained by allergy. There was a higher proportion of low or low-normal levels of IgG subclasses 1, 2, and 4 in these children than in normal children. Those who had low serum IgG values on initial measurement had a higher proportion of low or low-normal levels of IgG1, IgG2, and IgG4; those who had normal IgG values had a higher proportion of low or low-normal levels of IgG2 and IgG4. Thus a normal serum concentration of IgG did not exclude the possibility of an abnormal level of IgG2 or IgG4. Our experience suggests that abnormal levels of IgG subclasses might play an etiologic role in the chronic chest symptoms in some of these children.