SOLUBLE MEDIATORS RELEASED BY CD4+ T CELLS ACTIVATE BASOPHILS AND NEUTROPHILS IN THE CONTEXT OF IGE-MEDIATED ALLERGIC DISEASES

Abstract

The current paradigm in allergic diseases is that it is driven by Th2 responses, causing the influx of cells including eosinophils, basophils, neutrophils, and Th2 cells, giving rise to the late-phase response. Our lab previously showed that peptide immunotherapy can reduce allergic symptoms – this relief of symptoms coincides with a reduction of IL-8 in allergen-specific T cells. We hypothesized that T cell-derived soluble mediators such as IL-8 contributes to allergic inflammation by stimulating basophils and neutrophils to release histamine. In this study, we determined that IL-8 alone was unable to stimulate basophils to release histamine; however, in the presence of IL-3, IL-3 and IL-8 acted synergistically with subsequent anti-IgE stimulation to release histamine (observed fractional response: 0.807, compared to predicted fractional response if the effects were additive: 0.453). Supernatants derived from CD4+ T cells stimulated with anti-CD3/28 and Immunocult acted synergistically with subsequent anti-IgE stimulation to release histamine (observed fractional response: 0.636 [anti-CD3/28 at 1.0x106 cells/ml] and 0.754 [Immunocult at 2.5x106 cells/ml], compared to predicted fractional response if the effects were additive: 0.364 and 0.434, respectively). Basophils primed with anti-CD3/28 and Immunocult-stimulated T cell supernatants plus anti-IgE did not statistically increase the amount of histamine released, compared to media-stimulated T cell supernatant plus anti-IgE. Basophils were activated by T cell supernatants alone and when used for priming with anti-IgE, by upregulating CD63/CD203c markers (anti-CD3/28 alone, anti-CD3/28+anti-IgE, Immunocult alone, and Immunocult+anti-IgE: 60.7%, 85.3%, 87.7%, and 93.7% CD63/CD203c+, respectively, compared to media+anti-IgE (46.36% CD63/CD203c+). Neutrophils contained histamine (63.71nM per 106 neutrophils) and released significant amounts in response to stimulation by fMLP. Neutrophils did not release histamine in response to stimulation by supernatants derived from T cells. Neutrophils significantly downregulated CD62L when stimulated with supernatants derived from anti-CD3/28 and Immunocult-stimulated CD4+ T cells, and significantly up-regulated CD11b, compared to media-stimulated CD4+ T cells.