RESEARCH ON HUMAN AIRWAY EPITHELIUM ACTING AS ALLOANTIGEN-PRESENTING CELLS

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In lung allotransplantation, circulating leukocytes and vascular endothelial cells have been considered to be antigen-presenting cells (APCs). First in this research, we determined whether airway epithelial cells function as APCs.An immortal human epithelial cell line, BEAS-2B (B2B,1*10^5 cells/ml), which constitutively expresses both HLA-class I and class II antigens along with costimulatory molecules, ICAM-1, LFA-3, and B7 on its surface, was irradiated (50Gy) and transferred to 10ml of complete culture medium with allogeneic human peripheral blood lymphocyte (PBL) (1*10^6 cells/ml) from a healthy volunteer. The mixed lymphocyte-epithelial cell line culture (ML-AECL) was then incubated for 3 days, and harvested. As a control study, a one-way mixed lymphocyte culture (MLC) was also made up. Concentration of interleukin (IL) -10 in each supeynatant were assayd using an EASIA method. The concentration of IL-10 was not elevatedin MLC (9.3<plus-minus>11.8pg/ml, N=5) but significantly elev … More atedin ML-AECL (128<plus-minus>110pg/ml, N=5, p=0.043). Stimulation of B2B induceda population of allogeneic lymphocytes to proliferate and secrete IL-10. It has been reported that Th2, a subset of helper-T cells, secretes IL-10, which in turn inhibits both Th1 and cytotoxic T cells (CTLs) from proliferating and becoming active. We suggest that airway epithelial cells stimulate Th2, and, as a result, may play a role is suppressiing the allospecific reaction in acute rejection.Second, we investigated the role of costimulatory molecules on B2B.B2B were pretreated with either anti-HLA class I,anti-HLA class II,anti : ICAM-1, anti-LFA-3, or anti-B7 monoclonal antibody, Then the ML-AECL culture was then incubated, and harvested. Cell proliferation assay was performed using the colorimetric (MTT) assay. The MTT indeces (percentages relative to the control) were found to be significantly lower than the control when HLA class I,class II or LFA-3 on B2B was masked. In mixed culture consisting of B2B cells as stimulators and allogeneic lymphocytes, the lymphocytes recognized MHC-class I and II antigens expressed on the BEAS-2B.LFA-3 on BEAS-2B also contributed to the activation of lymphocyte alloreactivity. Less