Soluble Fc ϵR II levels in normal children and patients with immunodeficiency diseases

Abstract

CD23 is expressed on mature B cells and is identical to a low-affinity IgE Fc ϵ receptor type II (Fc ϵR II). The C terminal portion of CD23 is released to the serum as soluble Fc ϵR II (sFc ϵR II), which may be involved in regulation of IgE synthesis. We studied sFc ϵR II levels in normal children and in patients with immunodeficiencies, including common variable immunodeficiency (CVI), partial DiGeorge syndrome, and immunodeficiency associated with ectodermal dysplasia to examine the relationship of sFc ϵR II levels to B cell numbers and other immunoparameters. Serum Fc ϵR II levels are higher in younger children (younger than 3 years) and decline gradually with age. In 11 patients with CVI with normal numbers of B cells (>6%), sFc ϵR II levels were comparable to that of control subjects. Five patients with CVI with deficiencies of peripheral B cells had levels of sFc ϵR II similar to levels of control subjects. In all but one patient with partial DiGeorge syndrome, sFc ϵR II levels were not significantly elevated, despite the presence of elevated peripheral B cell numbers. Of six patients with ectodermal dysplasia, four demonstrated increased Fc ϵR II levels, a finding not correlated with serum IgE levels or with peripheral eosinophil or B cell numbers.