Tetanus toxin L chain is processed by major histocompatibility complex class I and class II pathways and recognized by CD8+ or CD4+ T lymphocytes.
Tetanus toxin (TeNT) is a heterodimeric protein antigen, whose light chain (L) is translocated in the cytosol of neuronal target cells specifically to cleave its substrates, vesicle-associated membrane protein-2 (VAMP-2, or synaptobrevin) or cellubrevin. We report that the L chain behaves as a nominal antigen recognized by specific T-cell clones upon either class I- or II-restricted presentation. Three types of responses are observed: (i) a TeNT- and L-specific CD8+ T-cell response, that can be inhibited in a dose-dependent manner by the proteasome inhibitor clasto-Lactacystin beta-lactone; (ii) a CD4+ T-cell response specific for L but not TeNT, with recognition of a determinant processed in a chloroquine-sensitive and brefeldin A-resistant compartment; (iii) a CD4+ T-cell response against both L and TeNT, with processing in a brefeldin A-sensitive compartment. The L chain processing was investigated in U937 cells by internalization and localization of L chain by separation of the cell content by differential centrifugation experiments. After incubation with TeNT or L chain in the presence of H chain, the L chain was predominantly distributed in the cytosolic fraction, whereas incubation with L alone led to localization in a lysosome/membrane fraction. The distribution of the TeNT L chain in both cytosolic and endocytic compartments of the antigen-presenting cell accounted for its processing by both class I and class II pathways. Furthermore, an epitope overlapping with the zinc-binding region was recognized by CD4+ and CD8+ T cells.
Kerblat
I
I
Laboratoire d'Immunochimie, CEA-G, INSERM U238, Universit¿e Joseph Fourier, Grenoble, France.
Tongiani-Dahshan
S
S
Aude-Garcia
C
C
Villiers
M
M
Drouet
C
C
Marche
P N
PN
D000938:Antigen-Presenting Cells / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018929:Cell Culture Techniques; D003017:Clostridium tetani / Q000276:immunology; D003600:Cytosol / Q000276:immunology; D000939:Epitopes / Q000032:analysis; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D013744:Tetanus Toxin / Q000276:immunology*; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000378:metabolism
D000942:Antigens, Bacterial; D000939:Epitopes; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D013744:Tetanus Toxin; D015032:Zinc