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 Africa n American and Hispanic patients in a general medical clinic and an al lergy/asthma clinic in East Harlem in New York City. Methods: Prospect ive measurement of immunoglobulins and IgG subclasses in a general med ical 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 v alues, 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 I gG(1) and IgG(3), 5 patients had low levels of IgG(2), and 18 patients had low levels of IgG(3). Because low IgG subclasses and allergy/asth ma appeared to be associated, we compared IgG subclass levels of the p atients with and without allergy/asthma. The mean IgG(2) level in the patients without allergy/asthma was 425.1 +/- 199.1 mg/dL (p = 0.05) c ompared with 345.5 +/- 133.1 mg/dL in the allergy/asthma group, the me an IgG(3) 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 IgG(1) and IgG(4) levels b etween 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 p opulations, especially in patients with asthma in East Harlem.