Biol.activity of galectin-3,the low affinity IgE receptor (FceRII/CD23) and soluble CD23.Role in cell developm.,cell adhesion,cytocine production,antigen presentation and IgE Syn.

In addition to the high affinity receptor for IgE (FcsRI), three other structures which are able to bind IgE have been identified; galectin-3 (originally called IgE binding protein), the low affinity IgE receptor IgE (Fc- epsilonRII/CD23) and soluble CD23 (sCD23). The biological roles of these proteins are at present not well understood and the following aspects require urgent further investigation: 1) To ascertain whether isoforms of Fc-epsilonRII on human mononuclear phagocytes exist, and to study the induction, modulation and biological functions of these structures. 2) The expression of galectin-3 in human bone marrow cells, resting and stimulated blood monocytes, B cells, leukemia B cells, activated T cells, and the secretion of galectin-3 into the cell supernatant. 3) The role of galectin-3, Fc-epsilonRII and sCD23 in cytokine or mitogen-driven cell proliferation and differentiation, and to identify the genes which are regulated by galectin-3. 4) Involvement of galectin-3, Fc-epsilonRII and sCD23 in the activation of human peripheral blood monocytes and Iymphocytes, and the mechanisms of signal transduction. 5) Influence of galectin-3 and sCD23 on production of interleukin-1 (IL-1), IL-2, IL-4, IL-5, IL-S, IL-10, IL-12, GM-CSF, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) by activated peripheral blood mononuclear cells from normal donors, allergic and leukemia patients. 6) The role of Fc-epsilonRII in the presentation of natural and recombinant birch pollen allergens (Bet v 1 and Bet v 2) by human peripheral blood B cells and monocytes to T helper (CD4+) cells: - The role of constitutive and cytokine-induced membrane Fc-epsilonRII, sCD23 as well as galectin-3 in cell adhesion, artigen uptake, focusing, processing and presentation to T helper cells and antigen-specific T cell clones. - The action of galectin-3 and sCD23 in the regulation of IgE synthesis, the molecular weights of sCD23 which have augmenting or suppressive activities and the nature of interaction with IL-4, IL-13 and IFN-gamma to alter IgE synthesis. A better understanding of the cellular and molecular mechanisms governing artigen recognition, artigen processing and presentation to T helper Iymphocytes, cytokine production and events leading to IgE synthesis, may lead to new approaches in the search for bester medical treatments, cost reductions in health care and improvements in the quality of life for patients.