ABSTRACT
We have developed a novel single-chain Ep-CAM-/CD3-bispecific single-chain antibody construct designated MT110. MT110 redirected unstimulated human peripheral T cells to induce the specific lysis of every Ep-CAM-expressing tumor cell line tested. MT110 induced a costimulation independent polyclonal activation of CD4- and CD8-positive T cells as seen by de novo expression of CD69 and CD25, and secretion of interferon gamma, tumor necrosis factor alpha, and interleukins 2, 4 and 10. CD8-positive T cells made the major contribution to redirected tumor cell lysis by MT110. With a delay, CD4-positive cells could also contribute presumably as consequence of a dramatic upregulation of granzyme B expression. MT110 was highly efficacious in a NOD/SCID mouse model with subcutaneously growing SW480 human colon cancer cells. Five daily doses of 1 microg MT110 on days 0-4 completely prevented tumor outgrowth in all mice treated. The bispecific antibody construct also led to a durable eradication of established tumors in all mice treated with 1 microg doses of MT110 on days 8-12 after tumor inoculation. Finally, MT110 could eradicate patient-derived metastatic ovarian cancer tissue growing under the skin of NOD/SCID mice. MT110 appears as an attractive bispecific antibody candidate for treatment of human Ep-CAM-overexpressing carcinomas.
Subject(s)
Antibodies, Bispecific/immunology , Antibodies, Bispecific/therapeutic use , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/therapeutic use , Neoplasms/drug therapy , Animals , Antibody Specificity , Antigens, CD19/metabolism , CD3 Complex/metabolism , CD4-Positive T-Lymphocytes/metabolism , CD8-Positive T-Lymphocytes/metabolism , Cell Line, Tumor , Cytotoxicity, Immunologic , Disease Models, Animal , Dose-Response Relationship, Drug , Humans , Kinetics , Lymphocyte Activation/immunology , Mice , Mice, Inbred NOD , Mice, SCID , Neoplasms/pathology , Recombinant Proteins/isolation & purification , Single-Chain AntibodiesABSTRACT
Although the CD4(+)- and CD8(+)-T-cell responses to the hepatitis B virus (HBV) are thought to be crucial for the control of HBV infection, the relative contribution of each T-cell subset as an effector of viral clearance is not known. To examine this question, we monitored the course of HBV infection in control, CD4-depleted, and CD8-depleted chimpanzees. Our results demonstrate that CD8(+) cells are the main effector cells responsible for viral clearance and disease pathogenesis during acute HBV infection, and they suggest that viral clearance is mediated by both noncytolytic and cytolytic effector functions of the CD8(+)-T-cell response.
Subject(s)
CD8-Positive T-Lymphocytes/physiology , Hepatitis B/immunology , Acute Disease , Animals , CD4-Positive T-Lymphocytes/physiology , Hepatitis B/virology , Interferon-gamma/biosynthesis , Pan troglodytes , Viral LoadABSTRACT
To define the early events that determine the outcome of acute hepatitis C virus (HCV) infection, we compared the course of viremia with the peripheral and intrahepatic T cell response and intrahepatic cytokine profile in six acutely infected chimpanzees. Three different outcomes were observed after peak viral titers were reached: sustained viral clearance, transient viral clearance followed by chronic infection, and chronic infection that persisted at initial peak titers. The results indicate that HCV spread outpaces the T cell response and that HCV rapidly induces but is not controlled by IFN-alphabeta; that viral clearance follows the entry and accumulation of HCV-specific IFN-gamma-producing T cells in the liver; and that it may not require the destruction of infected cells.