The high affinity receptor for IgE is the predominant IgE-binding structure in lesional skin of atopic dermatitis patients

While the skin of most patients with atopic dermatitis (AD) is known to contain IgE-bearing cells, the contribution of the various IgE-binding structures to this phenomenon is not fully understood. To address this issue, we eluted cell-bound IgE fi om cryostat sections of lesional AD skin by acid treatment and performed reconstitution experiments with IgE in the absence or presence of reagents directed against the currently known IgE-binding structures, We found that incubation of acid-treated sections, with either chimeric or serum IgE, resulted in the appearance of sizable numbers of anti-IgE-reactive cells. This cellular IgE loading could be entirely prevented by preincubation of the sections with the anti-Fc epsilon RI alpha MoAb 15-1 but not with either antibodies against Fc epsilon RII/CD23 and Fc gamma RII/CD32 or with alpha-lactose. To exclude the possibility that acid treatment of tissue sections may have adversely influenced the IgE-binding capacity of IgE receptors other than Fc epsilon RI, we performed an identical series of experiments on AD skin samples that, as an exception, were essentially devoid of anti-IgE-reactive cells, Again, no IgE loading was detected when these sections were preincubated with anti-Fc epsilon RI alpha MoAbs. In contrast, preincubation of the sections with alpha-lactose and/or MoAbs against Fc epsilon RII/CD23 or Fc gamma RII/CD32 did not affect IgE loading, Together with the observations that anti-Fc epsilon RI alpha-reactive and IgE-binding cells are largely overlapping populations and include cells of the Langerhans cell/dendritic cell lineage, mast cells, and a few dermal dendrocytes and eosinophils, our results demonstrate that Fc epsilon RI is the predominant and, perhaps, the only biologically relevant IgE-binding structure on, histogenetically and functionally diverse cell populations of AD skin.