Immunoglobulin and IgG subclass levels in the African American and Hispanic populations of east Harlem.

BACKGROUND

The normal levels of immunoglobulin and IgG subclasses in African American and Hispanic populations are uncertain. To determine immunoglobulin and IgG subclass levels in this community, we measured serum IgG, IgM, and IgA levels along with IgG subclasses in 303 African American and Hispanic patients in a general medical clinic and an allergy/asthma clinic in East Harlem in New York City.

METHODS

Prospective measurement of immunoglobulins and IgG subclasses in a general medical clinic and an allergy/asthma clinic in East Harlem.

RESULTS

Ten (3.4%) patients had IgG levels below the lower limit of normal values, two (0.07%) patients had IgA levels below the lower limit of normal values, and two (0.07%) patients had an IgM level below the lower limit of normal values. Twenty-four (8.1%) patients had IgG subclass levels below the lower limit of normal values; 1 patient had low levels of IgG1 and IgG3, 5 patients had low levels of IgG2, and 18 patients had low levels of IgG3. Because low IgG subclasses and allergy/asthma appeared to be associated, we compared IgG subclass levels of the patients with and without allergy/asthma. The mean IgG2 level in the patients without allergy/asthma was 425.1 +/- 199.1 mg/dL (p = 0.05) compared with 345.5 +/- 133.1 mg/dL in the allergy/asthma group, the mean IgG3 level in the patients without allergy/asthma was 85.0 +/- 57.1 mg/dL compared with 64 +/- 34.1 mg/dL in the allergy/asthma group (p = 0.016) but there were no differences in IgG1 and IgG4 levels between the two groups.

CONCLUSION

Altogether, our data indicate that humoral immunoglobulin and IgG subclass levels below the lowest normal values occur in the low socioeconomic African American and Hispanic populations, especially in patients with asthma in East Harlem.