title: Recombinant gamma interferon increases the binding of peripheral blood mononuclear leukocytes and a Leu-3+ T lymphocyte clone to cultured keratinocytes and to a malignant cutaneous squamous carcinoma cell line that is blocked by antibody against the LFA-1 molecule.
abstract: Because keratinocytes (KCs) express HLA-DR in a wide variety of skin diseases in which mononuclear leukocytes are observed in close apposition to KCs (i.e., graft-versus-host disease), and since gamma interferon (IFN-gamma) induces HLA-DR expression on KCs, we asked whether IFN-gamma treatment of KCs would influence the adherence of mononuclear leukocytes. When allogeneic peripheral blood mononuclear leukocytes (PBML) and a Leu-3+ T cell clone were coincubated with IFN-gamma-treated KCs (300 U/ml, 3 days), there was a marked increase in binding compared with nontreated KCs. Similar binding results were obtained using a cutaneous squamous carcinoma cell line (SCL-1) after IFN-gamma treatment. The IFN effect was relatively specific for IFN-gamma, as neither IFN-alpha nor -beta had any effect. Tumor necrosis factor exposure (500 U/ml, 3 days) increased the binding of the Leu-3+ T cell clone to both KCs and SCL-1 cells. Neutrophils displayed a less marked (but statistically significant) increase in binding to IFN-gamma-treated KCs. Using the Leu-3+ cell clone and SCL-1 cells, detailed kinetic analysis of the effect of IFN-gamma on binding was performed. The increased adherence between the cells began to appear after only 7 hours of treatment with r-IFN-gamma (300 U/ml) and reached a plateau at 48 hours, with significantly enhanced binding continuing for at least 48 hours after removal of IFN-gamma. The mechanism of binding was explored by preincubation of the PBML/Leu-3+ T cells with anti-LFA-1 (lymphocyte function-associated antigen) antibody (0.6-6.0 micrograms/ml), which totally inhibited the binding with no effect by anti-LFA-2 or -3 or class I or II antibodies despite documented binding of these antibodies to the cells. These results suggest that, after exposure to IFN-gamma, the ability of KCs to bind mononuclear leukocytes is strongly enhanced, and this adherence may be important in leukocyte trafficking in the skin as well as contributing to altered KC-leukocyte interaction, which may be of fundamental importance in a variety of skin disease.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000503:physiopathology*; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D002999:Clone Cells; D000078404:Epidermal Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D007633:Keratins; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000502:physiology*; D009504:Neutrophils / Q000502:physiology; D011994:Recombinant Proteins; D012878:Skin Neoplasms / Q000473:pathology / Q000503:physiopathology*; D013050:Spectrometry, Fluorescence; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D011994:Recombinant Proteins; D007633:Keratins; D007371:Interferon-gamma