Integrins of the β1 Family Influence Keratinocyte–Lymphocyte Interaction

Data from the literature indicate that ICAM-1 molecules play an important role in keratinocyte interactions with lymphocytes via the lymphocyte function-associated-1 lymphocyte-adhesion molecule. We examined the role of β1 integrins in keratinocyte–lymphocyte adhesion under different activation conditions. Among the β1 integrins expressed on keratinocytes and lymphocytes detected by indirect immunofluorescence microscopy and flow cytofluorometry, primarily the α2 and the α3 subunits on both cell types were involved in keratinocyte–lymphocyte adhesion. Moreover, the highest adhesion level was observed when both cell types were activated by IFN-γ for keratinocytes and phorbol 12-myristate 13-acetate for lymphocytes, suggesting that the former involved the protein kinase C pathway. Keratinocyte activation, characterized by the expression of ICAM-1, a decrease of β1 integrins, and the absence of α5β1 integrin, was required for optimal lymphocyte adhesion. Thus, β1 integrins remaining at the surface of IFN-γ-treated keratinocytes could be activated by this cytokine, and could synergize with ICAM-1 and lymphocyte function-associated-1 molecules to consolidate keratinocyte–lymphocyte adhesion