title: CD11a/CD18 (LFA-1) epitopes involved in syncytium formation among CD4+ T-cells following cell free HIV-1 infection.
abstract: Like particular monoclonal antibodies to CD4, monoclonal antibodies to epitopes localized at the top of the alpha-subunit (CD11a) and at the stem of the beta-subunit (CD18) of the lymphocyte function associated antigen-1 (LFA-1) block syncytium formation when added to CD4+ T-cells before or shortly after (5 min) cell free HIV-1 is added. This indicates involvement of LFA-1 epitopes in the early stage of cell-free infection. Syncytium formation is still blocked by CD4 antibodies when added two hours after virus adsorption, CD11a and CD18 antibodies are ineffective at this late stage. Radio-immune precipitation experiments in acutely infected T-cells with the appropriate CD11a and CD18 antibodies suggested a link between CD18 and CD4 in the cell lines studied, possibly mediated by the CD3/TCR complex. In chronically infected cells, where little CD4 is expressed, LFA-1 antibodies still precipitate the viral envelope, pointing to a direct LFA-1 envelope interaction in that late stage of infection. Our results indicate that a limited number of LFA-1 epitopes is involved in syncytium formation among T-cells, none of which is required for virus entry in the cell or virus spread in the culture.
authors.affiliation: Human Retrovirus Laboratory, Department of Virology, Amsterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Goudsmit
authors.forename: L
authors.initials: L
authors.lastname: Smit
mesh_terms: D018821:CD18 Antigens; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology*; D011233:Precipitin Tests; D016028:Receptors, Leukocyte-Adhesion / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D018821:CD18 Antigens; D000939:Epitopes; D016169:Lymphocyte Function-Associated Antigen-1; D016028:Receptors, Leukocyte-Adhesion