Specific antigen targeting to surface IgE and IgG on mouse bone marrow-derived mast cells enhances efficiency of antigen presentation.

The discovery that bone marrow-derived mast cells can express major histocompatibility complex class II molecules and act as antigen-presenting cells prompted us to evaluate this function when antigen is internalized through fluid-phase endocytosis or via specific uptake by using IgG and IgE antibodies. This study was performed using a specific T-cell hybridoma developed against Lol p 1, the major allergen of grass pollen Lolium perenne. Expression of Fc gamma R and Fc epsilon RI by mast cells led us to investigate the influence of IgG- and IgE-targeted antigen on the antigen-presenting function of mast cells.

IL-4 mRNA transcription is induced in mouse bone marrow-derived mast cells through an MHC class II-dependent signaling pathway.

We have previously shown that mouse bone marrow-derived mast cells (BMMC) can process and present immunogenic peptides to CD4 T cells. Here, we report on a T cell-dependent MHC class II-mediated mast cell activation resulting in IL-4 transcription and protein release. Presentation of optimal doses of ovalbumin peptide 323-339 resulted in IL-2 production by a specific T cell hybridoma and increase in IL-4 mRNA transcription in mast cells.

Exogenous and endogenous antigens are differentially presented by mast cells to CD4+ T lymphocytes.

In the present work, we explored the cytokine-dependent regulation of bone marrow-derived mast cell (BMMC) antigen-presenting cell (APC) function, and co-stimulation requirements, and analyzed the nature of antigens presented to T cells. We observed an up-regulation of the APC function of mast cells induced by granulocyte/macrophage-colony-stimulating factor (GM-CSF) and a complete abrogation by interferon (IFN)-gamma. Expression of co-stimulatory molecules CD80 and CD86 was suggested by the ability of mast cells to activate purified lymph node-derived T cells.

Mouse bone marrow-derived mast cells and mast cell lines constitutively produce B cell growth and differentiation activities.

The present report describes a novel function of mast cells that consists of a B cell growth activity. The B cell response occurred without any stimulation or preactivation of mast cells. A small number of mast cells was required, since mast cell/B cell ratios as low as 1/100 to 1/10,000 lead to effective B cell activation.

Presentation of soluble antigens by mast cells: upregulation by interleukin-4 and granulocyte/macrophage colony-stimulating factor and downregulation by interferon-gamma.

We recently showed that bone marrow-derived mast cells bore MHC class II molecules and could present antigens to specific T cell hybridomas. This article summarizes the effects of purified recombinant cytokines on the expression of MHC class II molecules by mast cells and on their antigen-presenting capacity. Since IL-3 is essential for mast cell growth, all the cytokines were analyzed in the presence of IL-3.