Synergistic T cell activation via the physiological ligands for CD2 and the T cell receptor.
T cells may be activated either by the antigen-specific T cell receptor (TCR)-CD3 complex or the cell surface receptor CD2. A natural ligand for CD2 has been found to be lymphocyte function-associated antigen 3 (LFA-3), a widely distributed cell surface glycoprotein. To investigate the interaction of these two pathways, we have expressed the cDNA encoding the human CD2 molecule in a murine T cell hybridoma that produces IL-2 in response to HLA-DR antigens. Expression of the CD2 molecule markedly enhances IL-2 production in response to LFA-3+ antigen-bearing stimulator cells, and this stimulation is inhibited by anti-CD2 and anti-LFA-3 mAb. To further define the role of LFA-3 in antigen-dependent T cell activation, we have studied the ability of the purified ligands of CD2 and the TCR to stimulate the hybridoma. Neither liposomes containing purified HLA-DR antigens nor liposomes containing purified LFA-3 were able to stimulate the parent or the CD2+ hybridoma. However, liposomes containing both purified LFA-3 and HLA-DR, the physiological ligands for CD2 and the TCR, respectively, stimulate IL-2 production by the CD2+ but not the parent hybridoma, suggesting that complementary interactions between the TCR-CD3 complex and the CD2 pathway may regulate lymphocyte activation. To determine whether the CD2/LFA-3 interaction participates in cell-cell adhesion and provides an activation signal, we have constructed a cytoplasmic deletion mutant of CD2, CD2 delta B, in which the COOH-terminal 100 amino acids of CD2 have been replaced with a serine. Hybridomas expressing the CD2 delta B molecule were examined. Deletion of the cytoplasmic domain of CD2 did not alter binding of LFA-3 but eliminated the ability of CD2 to increase the response of the hybridoma to liposomes containing both HLA-DR and LFA-3, demonstrating that adhesion of LFA-3 to CD2 alone was insufficient for activation, and that the cytoplasmic domain was required for LFA-3 stimulation through the CD2 molecule. T cells may be activated by purified LFA-3 binding to CD2 and the TCR interacting with its ligand, and these signals appear to be synergistic for the T cell. These results suggest that the CD2/LFA-3 interaction not only plays a role in cell-cell adhesion but provides a stimulatory signal for T cell activation.
Bierer
B E
BE
Division of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115.
Peterson
A
A
Gorga
J C
JC
Herrmann
S H
SH
Burakoff
S J
SJ
D000595:Amino Acid Sequence; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000502:physiology*; D000954:Antigens, Surface / Q000502:physiology*; D018801:CD2 Antigens; D018968:CD58 Antigens; D002448:Cell Adhesion; D004252:DNA Mutational Analysis; D006801:Humans; D006825:Hybridomas; D007376:Interleukin-2 / Q000096:biosynthesis; D008024:Ligands; D008081:Liposomes; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D011971:Receptors, Immunologic / Q000235:genetics / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*; D014162:Transfection
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018801:CD2 Antigens; D018968:CD58 Antigens; D007376:Interleukin-2; D008024:Ligands; D008081:Liposomes; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic