In light of the data in this work, we find that airway epithelial cells, which constitutively express B7 costimulatory molecules, can regulate the proliferation and differentiation of T cells in the airways by antigen presentation processes. In addition, silencing of ITGB4 in asthma airway epithelial cells led to impaired antigen presentation. In turn, the proliferation of T cells was inhibited, and production of IFN-gamma was decreased, IL-17 was increased, which may relate to Th2 inflammation bias and neutrophil production on asthma airway. These data partly elucidate the role that epithelial cells play in the inflammation phenomenon of asthma and bring some new useful clues to our understanding of the pathogenesis of immune surveillance and inflammation responses in asthma. Monoclonal antibodies are well-established as therapeutics, diagnostics, and reagents for research, but their use is currently limited by the difficulties and costs associated with identifying mAbs with the required affinity and specificity. Many targets of interest are highly conserved proteins, and immune regulation limits antibodies that can be obtained from a physiological immune response. In addition, many key therapeutic targets are cell surface proteins, which present particular challenges to mAb development because their physiologically active conformations are not readily recapitulated by purified proteins or membrane preparations used for immunization to elicit specific antibodies. This includes some especially high value targets, such as cytokine receptors and G protein-coupled receptors. Most current strategies for mAb discovery depend on in vivo and in vitro approaches. In vivo approaches depend on activation and selection of specific B cells by immunization, followed by generation of hybridomas. This process is costly and timeconsuming, since extensive screening and, in many cases, subsequent steps including affinity maturation are required to obtain mAbs with desired properties. It is also limited by immune tolerance, making some antigens difficult or impossible to target. In addition, once a mAb has been identified there is not a straightforward path to further optimization of affinity or functionality. In vitro approaches rely on screening massive numbers of synthetic single-chain antibodies, typically displayed on phage. These antibodies are expressed by cloned genes that encode linked VH and VL regions derived from an immune repertoire, often from a convalescent individual. They can be further optimized by iterative PCR-based mutagenesis accompanied by selection in vitro, using high throughput approaches. However, success in the end depends on the quality of the starting libraries and their sources, and not all single-chain antibodies can be readily converted to natural antibodies for practical applications. mAb discovery can also be carried out ex vivo in immortalized B cells. B cells display immunoglobulin molecules on the cell surface, facilitating selection for antigen recognition. In some B cell lines, physiological pathways for Ig gene diversification remain active, enabling evolution of high affinity antibodies in culture. The chicken B cell line, DT40, has proven especially adaptable for such purposes. DT40 Dirithromycin derives from a bursal lymphoma, and cells constitutively diversify their VH and VL genes. Ongoing diversification occurs by two pathways. Most (S)Ginsenoside-Rh2 mutations are templated and arise as a result of gene conversion, with nonfunctional pseudo-V regions serving as donors for transfer of sequence to the rearranged and transcribed V gene.