ABSTRACT
The role of interferon (IFN) gamma in controlling chronic infections of Listeria monocytogenes (Listeria) was studied in athymic C57BL/6 nu/nu mice, and by treating thymectomized C57BL/6 +/+ mice with monoclonal rat CD4 and CD8-specific monoclonal antibodies (Mab). Mice treated with a combination of the two T cell subset antibodies were similar to athymic, nude mice in being able to control Listeria infection, keeping the titers below 3-5 log10 bacteria per organ, but they could not eliminate them completely. Treatment with antibodies to IFN gamma of nude or CD4+ + CD8+ - T cell-depleted mice suffering from chronic Listeria infection caused a marked increase of Listeria titers in liver and spleen. This result implies a role of IFN gamma in maintaining anti-Listeria resistance in mice lacking mature T cells.
Subject(s)
Interferon-gamma/physiology , Listeriosis/immunology , T-Lymphocytes/immunology , Animals , Antibodies, Monoclonal/pharmacology , Immunization, Passive , Interferon-gamma/immunology , Leukocyte Count , Mice , Mice, Inbred C57BL , Mice, Nude , T-Lymphocytes, Helper-Inducer/immunology , T-Lymphocytes, Regulatory/immunology , ThymectomyABSTRACT
Autocrine production of growth factors may contribute to the rapid and fatal proliferation of acute hematologic malignancies. We have investigated whether the more controlled growth of less aggressive malignancies such as chronic myeloid leukemia (CML) may be associated with autocrine production of growth inhibitory factors. TNF inhibits the growth of both normal and leukemic hemopoietic progenitor cells. We find that exogenous TNF reduces the viability and DNA synthesis of purified myeloid cells from patients with CML and inhibits myeloid colony formation by patient progenitor cells. However, unlike progenitor cells from normal donors, patient myeloid progenitor cells also constitutively express mRNA for TNF and secrete functional TNF protein in culture. This endogenous TNF impedes the growth of CML cells because anti-TNF mAb shown to neutralize bioactive human TNF increases CML cell DNA synthesis whereas non-neutralizing anti-TNF mAb has no effect. Production of TNF by CML cells is not associated with production of lymphotoxin (TNF-beta), IL-1 or IL-6. TNF-mediated autocrine growth inhibition may contribute to the maintenance of the stable, chronic phase of this disease and similar mechanisms may operate in other malignancies to limit tumor proliferation. Competition between autocrine growth promoting and inhibiting factors may underlie the observed differences in biologic behavior between acute and chronic malignancies.
Subject(s)
Growth Inhibitors/pharmacology , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Tumor Necrosis Factor-alpha/pharmacology , Antibodies, Monoclonal/pharmacology , Cell Division/drug effects , Cell Separation , Cell Survival/drug effects , DNA/biosynthesis , Growth Inhibitors/analysis , Growth Inhibitors/immunology , Hematopoietic Stem Cells/analysis , Hematopoietic Stem Cells/immunology , Hematopoietic Stem Cells/pathology , Humans , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/immunology , Leukocytes, Mononuclear/analysis , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/pathology , Phenotype , RNA, Messenger/analysis , Recombinant Proteins/pharmacology , Tumor Necrosis Factor-alpha/analysis , Tumor Necrosis Factor-alpha/immunology , Tumor Stem Cell AssayABSTRACT
In this study, monoclonal antibodies (MABs) to human interferon alpha (HuIFN alpha) were evaluated for their suitability for the quantification of different HuIFN alpha preparations by conventional immunoassay methods. The results obtained using four different MABs were compared and suggest that whilst immunoassays can be highly sensitive and reproducible to perform, calibration of antigen content in relation to units of biological activity remains a problem, particularly because of the molecular and biological heterogeneity of HuIFN alpha preparations. Nevertheless, the judicious selection of MABs specific for an individual HuIFN alpha subtype has indicated that immunoassays may be accurately calibrated in units of biological activity for potency estimations of that HuIFN alpha subtype.
Subject(s)
Antibodies, Monoclonal , Interferon Type I/standards , Biological Assay , Enzyme-Linked Immunosorbent Assay/methods , Humans , Immunoassay , Interferon Type I/classification , Interferon Type I/immunologyABSTRACT
Specific polyclonal antisera to human interferon-alpha 1 (HuIFN-alpha 1), human interferon-alpha 2 (HuIFN-alpha 2) and human lymphoblastoid interferon (HuIFN-alpha Ly Namalwa) have been raised in rabbits and sheep. The antisera raised against HuIFN-alpha 1 and HuIFN-alpha 2 strongly neutralized the antiviral activity of their homologous IFN-alpha subtypes, but were less active against the heterologous IFN-alpha subtypes and preparations containing mixtures of IFN-alpha subtypes, e.g. human leukocyte interferon (HuIFN-alpha Le). Antisera raised against HuIFN-alpha Ly Namalwa strongly neutralized the antiviral activity of all IFN-alpha-containing preparations and showed weak cross-reactivity with human interferon-beta (HuIFN-beta). Neither anti-HuIFN-alpha 1 nor anti-HuIFN-alpha 2 could be demonstrated to neutralize the antiviral activity of HuIFN-beta. A number of monoclonal antibodies to HuIFN-alpha 2 have been prepared and these were found to neutralize HuIFN-alpha 2 antiviral activity to varying degrees, but not to neutralize the heterologous subtype HuIFN-alpha 1, preparations containing mixtures of IFN-alpha subtypes or HuIFN-beta.
