TCT.1, a target molecule for gamma/delta T cells, is encoded by an immunoglobulin superfamily gene (Blast-1) located in the CD1 region of human chromosome 1.
We have recently generated a series of gamma/delta T cell clones able to kill, after in vitro immunization, an Epstein-Barr Virus-transformed B cell line (designated E418) in a non-major histocompatibility complex-requiring fashion. A monoclonal antibody, termed anti-10H3, produced against E418 was selected by its ability to block these cytotoxic interactions. Further analysis indicated that the inhibitory effects of anti-10H3 were highly selective (i.e., no blocking activity with multiple control clones used as effector cells; no alteration of the natural killer-like function mediated by the relevant gamma/delta clones against 10H3+ tumor cells such as Rex). The molecule immunoprecipitated by anti-10H3, termed TCT.1, was characterized as a 43-kD protein broadly distributed in the hematopoietic system. The TCT.1 molecule has been further studied here by protein microsequencing. Results show that the TCT.1-derived peptide sequences are virtually identical to corresponding regions of Blast-1, a previously described surface protein with unknown function. The likely identity of the two molecules has been strengthened by analyzing the susceptibility of TCT.1 to phosphatidylinositol-specific phospholipase C digestion in light of the known anchorage of Blast-1 to the cell membrane through a glycosyl-phosphatidylinositol-containing lipid. The TCT.1/Blast-1-encoding gene is well characterized; it belongs to the immunoglobulin gene superfamily and it is located in the same band of chromosome 1 as the CD1 gene cluster. Together, these data further support the view that proteins distinct from the conventional class I/II histocompatibility molecules are involved in specific T cell recognition.
Del Porto
P
P
Laboratoire d'Hémato-Immunologie, INSERM, U333, Institut Gustave-Roussy, Villejuif, France.
Mami-Chouaib
F
F
Bruneau
J M
JM
Jitsukawa
S
S
Dumas
J
J
Harnois
M
M
Hercend
T
T
D000595:Amino Acid Sequence; D015703:Antigens, CD; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology*; D000071178:CD48 Antigen; D002460:Cell Line; D002878:Chromosomes, Human, Pair 1; D003602:Cytotoxicity, Immunologic; D006017:Glycolipids / Q000378:metabolism; D017261:Glycosylphosphatidylinositols; D006801:Humans; D007111:Immunity, Cellular; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta
D015703:Antigens, CD; D000954:Antigens, Surface; D000071178:CD48 Antigen; C000604065:CD48 protein, human; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D010716:Phosphatidylinositols; D011948:Receptors, Antigen, T-Cell; D016692:Receptors, Antigen, T-Cell, gamma-delta