Characterization of T cell-expressed chimeric receptors with antibody-type specificity for the CD4 binding site of HIV-1 gp120.
Chimeric T cell receptors (cTCR) with an antibody specificity have been proposed in several models as a combination of antibody and cellular immunotherapy without MHC restriction. Such a tool could be of a limited use in HIV infection because of the great variability of the virus. The human single-chain antibody (ScFv-b12) derives from the b12 antibody directed to the CD4 binding site of gp120, a potent neutralizer of different HIV-1 strains, including a large panel of primary isolates. A single-chain fragment variable (ScFv) bearing the VH Pro-->Glu mutation that improves b12 affinity 54-fold, called ScFv-b12E, was also constructed. The ScFv were linked to the signal-transducing y chain of the Fc(gamma)RIII, with or without spacer region, and expressed in the murine MD45 T cell line. The different cTCR formats behave similarly in terms of ScFv surface expression, but differ according to their activation threshold. T cell transfectants can be stimulated with immobilized gp120 derived from all HIV strains tested. BHK cells infected with Semliki forest virus (SFV) carrying an HIV-1 envelope gene (SFV-env) derived from either HIV-1 laboratory strains (LAI, MN12, HXB2) or field isolates (BX08, CHAR or 133) were used as targets for the transfectants. All gp120-expressing cells induced cTCR-specific activation. The latter result is contrasting with the lack of specific recognition of SFV-CHAR- or 133-infected cells by the native b12 antibody, as measured by cytofluorometric analysis. Finally, HeLa cells (which constitutively express the coreceptor CXCR4) are able to bind HIV-1 gp160 when transfected with the chimeric receptor ScFv-b12-gamma, but, importantly, do not become infected by the virus. Our results therefore suggest that cTCR with b12 specificity can confer to T cells broad anti-HIV reactivity without making them susceptible to HIV infection.
Bitton
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N
Laboratoire d'Immunologie Cellulaire, CERVI, UMR CNRS 7627, Hopital Pitié-Salpétrière, Paris, France.
Verrier
F
F
Debré
P
P
Gorochov
G
G
D000918:Antibody Specificity; D001665:Binding Sites / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D007136:Immunoglobulins; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins