Characterization of human T cell-derived IgE-potentiating factor

Area of Science:

• Immunology
• Allergy Research
• Molecular Biology

Background:

• Previous studies demonstrated Fc epsilon receptor-positive (Fc epsilon R+) T cell lines from hyper IgE syndrome patients secrete IgE-binding factors.
• These factors selectively enhance immunoglobulin E (IgE) but not immunoglobulin G (IgG) synthesis in B cells from allergic rhinitis patients, not nonatopic subjects.

Purpose of the Study:

• To investigate the effect of supernatants from Fc epsilon R+ T cell lines on a panel of B cells from atopic patients.
• To further characterize the IgE-potentiating factors derived from Fc epsilon R+ T cell lines.

Main Methods:

• Testing supernatants from Fc epsilon R+ T cell lines on B cells from 20 atopic patients.
• Characterizing IgE-potentiating factors using Sephadex G-75 fractionation and lectin affinity.
• Assessing the impact of exogenous human IgE and tunicamycin on factor release.

Main Results:

• IgE synthesis was selectively enhanced only in atopic B cell cultures with ongoing spontaneous IgE synthesis.
• The target of IgE-potentiating factors was identified as large, low-density B cells in atopic donors.
• Factors fractionated into two peaks (15,000 and 60,000 kDa) with affinity for lentil lectin but not peanut agglutinin.
• Factor release was enhanced by exogenous human IgE and inhibited by tunicamycin (an N-glycosylation inhibitor).

Conclusions:

• Human IgE-potentiating factors selectively enhance IgE synthesis in specific atopic B cells.
• Physicochemical characteristics of human IgE-potentiating factors show homology with rodent factors.
• These findings highlight the complex immune regulation of IgE production in atopy.