Affiliation:
1. Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814.
Abstract
Abstract
The parameters necessary for induction of high-rate IgA class switching are unknown. Thus, although TGF-beta is switch factor for the IgA class, the percentage of membrane (m)IgA+ cells generated in vitro in response to TGF-beta and various individual modes of B cell activation is limited to 1 to 2% of the total B cell population, a percentage far below that observed within Peyer's patches. In this report we determined a set of parameters that act synergistically to generate up to 15 to 20% mIgA+ cells in vitro. A dual mode of B cell activation is required whereby signaling through CD40 or in response to LPS stimulation must occur in concert with multivalent Ag receptor crosslinking. A complex cytokine requirement is also revealed in that both IL-4 and IL-5 must be present with TGF-beta for high-rate IgA class switching to occur. By contrast, IFN-gamma, a known antagonist of IL-4, strongly suppresses the induction of mIgA+ cells in response to these stimuli. This novel cellular system should serve as a powerful tool for studying the molecular mechanisms that underly the IgA class switch and may provide insight into the physiologic parameters that induce it.
Publisher
The American Association of Immunologists
Subject
Immunology,Immunology and Allergy
Cited by
9 articles.
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