Activation of Lyt-2+ T cells by antibodies towards brain-associated antigens. II. Antibody-dependent induction of "nonspecific" cell-mediated cytotoxicity

Targeted macrophage cytotoxicity using a nonreplicative live vector expressing a tumor-specific single-chain variable region fragment

Antigen-specific recognition and subsequent destruction of tumor cells is the goal of vaccine-based immunotherapy of cancer. Often, however, tumor antigen-specific cytotoxic T lymphocytes (CTLs) are either not available or in a state of anergy. In addition, MHCI expression on tumor cells is often downregulated. Either or both of these situations can allow tumor growth to proceed unchecked by CTL control. We have shown previously that tumor antigen-specific monoclonal antibodies can be expressed in vaccinia virus and that activated macrophages infected with this virus acquire the ability to kill tumor cells expressing that antigen. Here we show that a membrane-anchored form of the scFv portion of the MUC1 tumor antigen-specific monoclonal antibody, SM3, can be expressed on activated macrophages with the highly attenuated poxvirus, modified vaccinia Ankara (MVA), as a gene transfer vector. Cells infected with the MVA-scFv construct were shown to express the membrane-bound scFv by Western blot and FACS analysis. That cells expressing the membrane-anchored scFv specifically bind antigen was shown by FACS and by BIAcore analysis. GM-CSF-activated macrophages were infected with the construct and shown to recognize specifically MUC1-expressing tumor cells as measured by IL-12 release. Furthermore, activated macrophages expressing the membrane-bound scFv specifically lyse target cells expressing the MUC1 antigen but not cells that do not express MUC1.

Dual-label immunocytochemistry of the active multiple sclerosis lesion: major histocompatibility complex and activation antigens

Fresh-frozen autopsy material containing active inflammatory lesions from 9 different patients with multiple sclerosis (MS) was analyzed by immunocytochemistry using a panel of monoclonal antibodies, and a dual-label immunocytochemical method was developed which permitted the simultaneous detection of two different surface markers on a single cell. We now report the following. (1) The predominant T-cell phenotype within MS lesions is CD2,3,8. This phenotype marks the suppressor-cytotoxic subset. (2) These cells do not express the natural killer cell marker NKH-1, which is present on a subset of CD8-positive cells in peripheral blood. (3) The infiltrating cell expresses class I (HLA A, B, C), but not class II (DR and DQ), major histocompatibility complex (MHC) molecules. (4) Other T-cell surface molecules, including the activation antigens interleukin-2 receptor, Ta1, and T11-3, as well as the marker 2H4, are largely not expressed. (5) Endothelial cells express both class I and class II MHC molecules and the 4B4 molecule in both MS and control tissue. (6) Astrocytes within the vicinity of MS lesions are predominantly class II MHC-negative. These results demonstrate that the T-cell infiltrate present in MS tissue on autopsy has a restricted phenotypic profile, but they also raise the possibility that, within this population, few activated effector cells are present.