RELATIONSHIP OF HISTAMINE-RELEASING FACTORS AND HISTAMINE-RELEASING INHIBITORY FACTORS TO CHEMOKINE GROUP OF CYTOKINE

The release of mediators from mast cells and basophils represents the central event in the development of immediate hypersensitivity reactio ns with release of substances such as histamine, Leukotrienes C-4/D-4, Platelet Activating Factor (PAF), and Prostaglandin D-2. Cytokines su ch as IL-1, TNF alpha, and IL-4 may also be secreted. Histamine Releas ing Factors (HRF) are cytokine-like molecules that interact with basop hils and/or mast cells to cause cell activation and secretion of media tors. Histamine release is the best characterized of these and has bee n used as the assay for HRFs, but a wide variety of inflammatory media tors can potentially be secreted. We believe this type of cell to cell communication to be important in tissue inflammation, in which infilt rating cells may produce HRFs in proximity to infiltrating basophils a nd/or mast cells and cause them to degranulate. Such a reaction appear s to be independent of IgE antibody, may no longer require the presenc e of any inciting antigen, and appears to be pertinent to the allergic late phase reaction as it occurs in the nose, lungs, and skin. It is thought than an ongoing antigenic stimulus, as seem in seasonal or per ennial allergic rhinitis and asthma, or in certain types of urticaria, or in atopic dermatitis, leads to a perpetuating inflammatory reactio n that persists for many weeks or months. A chronic inflammatory react ion of this sort appears to be required for an allergic reaction (IgE mediated) to manifest as an allergic disease. The relationship of HRF to the chemokine group of cytokine-like molecules and the importance o f HRF in the pathogenesis of bronchial hyperreactivity and asthma has been reviewed in this paper.