B-cell subsets in patients with transient hypogammaglobulinemia of infancy, partial IgA deficiency, and selective IgM deficiency.

BACKGROUND The pathogenesis of some primary humoral immunodeficiencies, such as transient hypogammaglobulinemia of infancy (THI) and immunoglobulin (Ig) A deficiency, remains unknown and can render diagnosis problematic. OBJECTIVE In the present study, we used flow cytometry to analyze peripheral blood B-cell subsets in patients with THI and unclassified hypogammaglobulinemia (UCH), partial IgA deficiency, and selective IgM deficiency. METHODS The study population comprised 41 patients with hypogammaglobulinemia (THI, 18; UCH, 23), 16 patients with partial IgA deficiency, and 16 patients with selective IgM deficiency who were admitted to Ankara University Department of Pediatric Immunology-Allergy between January 2010 and April 2011, as well as 29 healthy controls. B-cell subsets were examined according to the EUROclass classification. RESULTS Age at diagnosis in the hypogammaglobulinemia group ranged between-14 months and 13 years (median, 26 months). Naive B-cell percentages were significantly higher and activated B-cell values lower in the THI patients than in the UCH patients and age-matched healthy controls. Nonswitched (IgM+CD27+IgD+) memory B-cell values were found to be significantly lower in patients with selective IgM deficiency than in healthy controls. No significant differences in B-cell subsets were found in patients with partial IgA deficiency. CONCLUSIONS Previous reports show that reduced class-switched memory B cell values are associated with CVID, THI, and selective IgA deficiency. Our findings did not support these reports. Furthermore, we observed that naive B cell values were higher in patients with THI. A maturation defect could play a role in the pathogenesis of THI.