Accessory cell function of airway epithelial cells.

Area of Science:

• Immunology
• Cell Biology
• Respiratory Medicine

Background:

• Airway epithelial cells (AECs) possess accessory cell features, including MHC class II molecules and Fcgamma receptors.
• Antigen (Ag) presentation machinery components like cathepsins, invariant chain, and HLA-DM are expressed by AECs.
• Costimulatory molecules B7h and B7-H1 are present on AECs, with B7-H1 expression inducible by cytokines.

Purpose of the Study:

• To investigate the antigen-presenting and costimulatory capabilities of airway epithelial cells (AECs).
• To compare the T cell stimulatory capacity of AECs with that of dendritic cells (DCs).
• To explore the role of AECs in local immune responses within the airways.

Main Methods:

• Analysis of mRNA expression for antigen presentation-related molecules and costimulatory molecules in AECs.
• Immunohistochemical colocalization of ragweed antigen with HLA-DR in AECs.
• Assessment of T cell proliferation, cytokine production, and apoptosis following allostimulation with AECs and DCs.

Main Results:

• AECs express mRNA for cathepsins, invariant chain, HLA-DM, and CLIP, and can present antigens like ragweed.
• Granulocyte-macrophage colony-stimulating factor and IFN-gamma increased ragweed uptake and B7-H1 expression on AECs.
• AECs stimulated T cell proliferation, albeit with a lower precursor frequency than DCs, and activated specific T cell subsets.

Conclusions:

• AECs possess functional antigen-presenting cell capabilities, including expression of costimulatory molecules.
• AECs can modulate T cell responses, suggesting a role in initiating and regulating local airway immunity.
• The strategic location of AECs positions them as key players in the immune surveillance of the respiratory tract.