Lateral organization of the ICAM-1 molecule at the surface of human lymphoblasts: a possible model for its co-distribution with the IL-2 receptor, class I and class II HLA molecules.
Lateral distribution of the ICAM-1 molecule and its topological relationship (mutual proximity) to the heavy and light chains of class I HLA molecules, HLA-DR and interleukin-2 receptor alpha-chain (IL-2R alpha) were studied in the plasma membrane of HUT-102B2 T and JY B lymphoblastoid cell lines by the technique of flow cytometric energy transfer (FCET). Effects of adherency and treatments with recombinant interferon-gamma or tumor necrosis factor-alpha on the relative expression level of ICAM-1 to the above cell surface proteins were also investigated. While the cytokines did not significantly affect the ICAM-1 level of either cell line, an increased ICAM-1 expression was found on adherent JY cells. The ICAM-1 expression varied significantly with the cell cycle and culture conditions, as well. The statistical analysis of the differences observed in the energy transfer efficiency histograms resulted in a possible model of lateral co-distribution of these proteins in the plasma membrane. These two-dimensional patterns proved to be different for T and B lymphoma lines. ICAM-1 molecules showed a high degree of self-association on HUT-102B2 (T) cells, while they were mainly expressed as monomers on the surface of JY (B) cells. Both cells showed a significant (ca. 30%) difference between densities of the heavy and light chains of class I HLA antigen, suggesting a substantial amount of beta 2-microglobulin free heavy chains on these cell lines. The class I HLA molecules also showed partial self-association, but on both cell lines. The beta 2-microglobulin and the heavy chain of the class I HLA showed strongly different proximities to the IL-2R alpha, HLA-DR and ICAM-1 molecules, indicating that their orientations relative to the other proteins are dissimilar. IL-2R alpha molecules of the HUT-102B2 (T) cells are located mostly in the vicinity of the beta 2-microglobulin. In contrast, the local density of HLA-DR antigens is higher in the proximity of the heavy chain than in the vicinity of the beta 2-microglobulin. The possible functional significance of these protein patterns is also discussed herein.
Bene
L
L
Department of Biophysics, Medical University School, Debrecen, Hungary.
Balázs
M
M
Matkó
J
J
Möst
J
J
Dierich
M P
MP
Szöllösi
J
J
Damjanovich
S
S
D000911:Antibodies, Monoclonal; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000032:analysis*; D002453:Cell Cycle / Q000276:immunology; D002460:Cell Line; D004735:Energy Transfer; D005434:Flow Cytometry; D006680:HLA Antigens / Q000032:analysis*; D006681:HLA-D Antigens / Q000032:analysis; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma / Q000502:physiology; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D006680:HLA Antigens; D006681:HLA-D Antigens; D015395:Histocompatibility Antigens Class I; D015375:Receptors, Interleukin-2; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma