Presence of IgE suppressor factors in human colostrum

Abstract

In spite of intensive investigations, the ability of breast feeding to delay and to attenuate atopic diseases in children remains debatable. This study documents a mechanism whereby breast feeding might interfere with the synthesis of IgE by breast-fed infants. Indeed, we show that colostrum contains IgE-binding factors (IgE-BF) capable of suppressing the in vitro synthesis of human IgE. Colostrum obtained from 15 donors was successively depleted of lipids and casein, filtered through Amicon XM50 membrane (mol. mass cut-off 50 kDa) and lyophilized. IgE-BF was demonstrated in such preparations by two different approaches, i.e. a classical rosette inhibition assay and Western blot analysis. In the first instance, lyophilized preparations of colostrum inhibited the binding of IgE-coated bovine erythrocytes to IgE recovered on the surface of RPMI 8866 lymphoblastoid cells. The rosette-inhibiting activity could be absorbed on IgE- but not on IgG-Sepharose 4B and it could be recovered in the eluate of IgE-Sepharose 4B. The molecular mass of IgE-BF was comprised between 10 to 20 kDa as estimated by gel filtration through a calibrated Sephadex G-75 column. After fractionation on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transfer to nitrocellulose membrane, colostrum displayed one band of 14 kDa and reacted with radiolabeled IgE but not with IgG nor IgM. This 14-kDa band could be removed by absorbing colostrum with IgE- but not with IgG-Sepharose 4B. Most importantly, the colostrum IgE-BF suppressed the spontaneous in vitro synthesis of IgE by B lymphocytes derived from allergic donors without altering the production of IgM.

Human Fc_εR II and IgE-Binding Factors

“…Indeed, the latter was shown to be a single copy gene [20], It was next demonstrated that IgE-BFs are generated by the protoeolytic cleavage of sur face FctR 11 and that they do not derive from an intra cellular post-translational cleavage of Fc,R II precursor molecules [12], The results from ongoing studies suggest that the 45-KD molecule is first trans formed into one of 37 KD which is then successively fragmented into 33-and 25-KD molecules. More over, IgE-BFs with a molecular weight of 16 KD have also been documented in human colostrum as well as in the culture supernatant of B and T cell lines [25].…”

Analysis of IgE-Binding Factors (sCD23) within Newborn Sera

“…In addition to binding of IgE, CD23 ex erts lectin-like properties [4], IgE-binding factors or solu ble CD23 are known to be present within several biolog ical fluids. They have been detected within supernatants of B and T cell lines, peripheral blood lymphocytes as well as monocyte-like cell lines (U937) [4], In addition, human sera and colostrum were shown to contain IgE-BF [27]; quite recently it has been reported that epidermal Langer hans cells release sCD23 after stimulation with IFN-y [28].…”

Ontogeny of Mucosal Immunity and Aging

“…This protracted period of increased membrane permeability may contribute to the higher incidence of infections (Fergusson et al, 1981;Forman et al, 1984;Goldblum et al, 1996;Myers et al, 1984) and atopic disease (Fallstrom et al, 1984;Lemmert et al, 2006) observed in non-breast-fed infants. A factor in colostrum that suppresses IgE synthesis may also contribute to the lower risk of atopy in breast-fed neonates (Sarfati et al, 1986).…”