Expression,purification,characterization And Primary Function Study Of A Novel Th2 Highly Express Protein-neutrophilic Granule Protein (ngp)

CD4~+ T cells can be divided into Th1 and Th2 subsets, which are defined by the cytokines they secrete. Thl cells secrete INF-γ, IL-2, TNF-αand TNF-β, which are critical for the eradication of intracellular pathogens such as Listeria monocytogenes and Leishmania major. Th2 cells produce IL-4, IL-13, IL-5, and IL-6 and are necessary for inducing the humoral response to combat parasitic helminthes and nematodes. The balance between Th1/Th2 subsets determines the susceptibility to disease states, where the improper development of Thl cells can lead to autoimmunity, while an overactive Th2 response can lead to allergy and asthma.Our understanding of Th cell biology has increased over the past several years, but some important questions remain. We used microarray to analysis the differential expression gene between Th1 cells and Th2 cells. NGP is found to be high expressed in Th2 celts, which was first identified as a myeloid-specific granule protein with homology to the cystatin superfamily and confirmed by RT-PCR and Real-time PCR. The results suggest a possible function for NGP in Th cell differentiation. Then we clone the NGP into the plasmid pEGFP-N1, and found the NGP-GFP fusion protein localizes to cytoplasm. Interestingly, the culture superant from the 293 T cell tranfected with NGP-pEGFP-N1 is able to inhibit the OVA induced splenocytes proliferation. In order to study the function of the NGP, we express and purify the NGP-GST proteins and get the antisera against the NGP. The westernblot confirmed that NGP is also highly expressed in Th2 cells at protein level. Meanwhile, we found that the purified protein can inhibit the splenocytes proliferation induced by OVA.In all, we find a new Th2 secreted protein that can inhibit the splenocytes proliferation induced by OVA..