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- Title
Function and regulation of FcεRI expression on monocytes from non--atopic donors.
- Authors
Reischl, I. G.; Corvaïa, N.; Effenberger, F.; Wolff-Winiski, B.; Krömer, E.; Mudde, G. C.
- Abstract
Background The high affinity receptor for IgE (FcϵRI) has recently been identified on antigen presenting cells, i.e. Langerhans cells and monocytes from atopic donors and it was hypothesized that FcϵRI expression levels correlated with allergy. Objective The aims of the study was to investigate the function and expression of FcϵRI on monocytes from non-atopic donors. Methods Purified monocytes or peripheral blood mononuclear cells were used to study FcϵRI expression and signal transduction on CD14 positive cells by flow cytometry and/or confocal laser microscopy. Results Freshly isolated monocytes from healthy individuals (n = 58) were shown to express FcϵRI (median 18%, range 2-66%). No IgE was bound to these receptors in vivo, and in vitro no significant binding of complete IgE molecules could be obtained. IgE positive monocytes from atopic donors were also found to have free FcϵRI, incapable of binding IgE in vitro. On all CD14 positive cells free FcϵRI expression was rapidly and completely lost during culture in conventional culture media (IMDM, RPMI) but not in phosphate buffered saline (PBS). Moreover, signal transduction through free FcϵRI appeared to be inhibited. However, both IgE binding and calcium mobilization were restored by treatment of fresh non-atopic monocytes with neuraminidase. Importantly, culturing these monocytes overnight in conventional medium containing 2μg/mL IgE induced a cycloheximide insensitive accumulation of IgE bound to FcϵRI and. in addition, led to cell activation. Conclusion Monocytes from both atopic donors and healthy individuals express FcϵRI, but the previously reported different expression levels between the two groups seem to be directly related to the absence or presence of IgE in the serum. This may be due to the fact that FcϵRI is subjected to a constant turnover process which is slowed down but not prevented by ligand binding. In addition, free Fee RI on non-atopic monocytes are under control of a neuramindase sensitive structure(s), which influences signal transduction and IgE binding.
- Subjects
LEUCOCYTES; MONOCYTES; MICROBIAL genetics; IMMUNOLOGIC diseases; DENDRITIC cells; SERUM
- Publication
Clinical & Experimental Allergy, 1996, Vol 26, Issue 6, p630
- ISSN
0954-7894
- Publication type
Article
- DOI
10.1111/j.1365-2222.1996.tb00589.x