Aspects of Immunobiology and Immunotherapy and Uses of Monoclonal Antibodies and Biologic Immune Modifiers in Human Gliomas

Immunological alterations in patients with primary tumors in central nervous system

Natural killer (NK) cells play an important role in immune surveillance against tumors. The present work aimed to study the cytotoxic activity of NK cells and T cell subsets in peripheral blood of 13 patients with primary tumors in central nervous system (CNS). As controls 29 healthy subjects with the age range equivalent to the patients were studied. The methods employed were: a) determination of cytotoxic activity of NK cells towards K562 target cells, evaluated by single cell-assay; b) enumeration of CD3+ lymphocytes and their CD4+ and CD8+ subsets defined by monoclonal antibodies; c) the identification of tumors were done by histologic and immunochemistry studies. The results indicated that adults and children with tumor in CNS display reduced percentage of total T cells, helper/inducer subset and low helper/suppressor ratio. The cytotoxic activity of NK cells was decreased in patients with CNS tumors due mainly to a decrease in the proportion of target-binding lymphocytes. These results suggest that cytotoxic activity of NK cells may be affected by the immunoregulatory disturbances observed in patients with primary tumors in CNS.

Biology and treatment of gliomas

This review discusses some of the recent advances in glioma research and treatment. Our understanding of the characteristics of these tumors has been strengthened by the application of molecular biologic and genetic techniques to pathologic grading and therapy outcome. Newer attempts to correlate imaging modalities to pathologic grading are also discussed. It is anticipated that these developments will strengthen our ability to design improved treatment strategies, an essential goal inasmuch as current treatment schemes have limited benefit. More work needs to be done to understand the biology of these tumors especially the complex interactions of their cytokine expression, multiplicity of genetic abnormalities, and their local environment. Only then will be able to develop improved therapeutic interventions.

Immunology of central nervous system tumors

With progress in cellular immunology and the development of hybridoma technology, the idea of manipulating host-tumor immune interactions to improve the prognosis of brain tumors has aroused renewed interest. Although no brain tumor-specific antigens have been found, and in spite of the wide antigenic heterogeneity of brain tumor cells, some monoclonal antibodies possessing restricted specificity have been isolated and their potential clinical applications investigated. One of the most pronounced changes in the cellular immune responses of brain tumor patients is a profound depression of the T4-helper lymphocytes. Clinical and laboratory trials are under way to assess the ability of lymphokines, such as gamma-interferon or interleukin-2, to restore immunologic competence in these patients and potentiate a specific anti-tumor immunologic response. Recent work suggests that the endothelium-astrocyte complex may have a pivotal role in assisting the escape of brain tumors from the host's immunologic responses, since it is responsible for the intracerebral sequestration of antigens and local anti-tumor responses. In this review, the data on the antigenic properties of central nervous system tumors and the host's humoral and cellular immune responses to them are analyzed and potential immunologic therapies are discussed.

Monoclonal antibodies with cytotoxic reactivities against human gliomas

Monoclonal antibodies (MAb's) reactive with human malignant glioma cells were derived from mice inoculated with cells from fresh glioma tissue. Seven MAb's were selected for study based on their high-level binding in immunoperoxidase and immunofluorescence assay to most of the glioma tissues derived from various patients and based on the absence of binding to normal bone marrow cells. Four of the seven MAb's did not bind to any of the four normal brain tissues tested, whereas three MAb's bound to one or two of these tissues. Two MAb's bound to the surfaces of cultured glioma cells in radioimmunoassay. One of these MAb's (AS-AY1, immunoglobulin (Ig)(G1) lysed cultured glioma cells with human lymphocytes or murine macrophages as effector cells; the other MAb (AS-AY2, IgM) was reactive in complement-dependent cytotoxicity assay. These two MAb's therefore seem especially promising reagents in approaches to immunotherapy of human malignant glioma.

Adjuvant intraarterial chemotherapy with nimustine in the management of World Health Organization Grade IV gliomas of the brain. Experience at the Department of Neurosurgery of Düsseldorf University

A protocol with postoperative adjuvant intraarterial (ia) chemotherapy using nimustine (ACNU) was followed at the University of Düsseldorf (Federal Republic of Germany) after histologic confirmation of malignant glioma of the brain. The first iaACNU procedure was performed within 10 days of surgery, and immediately before postoperative irradiation. After radiotherapy further iaACNU courses were given. The study population consisted of 35 primarily treated malignant gliomas World Health Organization (WHO) Grade IV, i.e., glioblastomas (NIV). Of these tumors 11 showed early progressive disease (PD) (NIV primPD), whereas 24 had stable or responsive disease (NIV SD&RD). Seven patients with recurrent malignant gliomas WHO Grade IV (NIV recurrent) were also treated plus six patients with malignant gliomas WHO Grade III (NIII). Experience with 50 treated patients resulted from this study. The median survival time (MST) for the group NIV was 14.2 months; 41.0% of patients were long-term survivors. The MST for the group NIV primPD was 7.8 months; 9.1% of patients were long-term survivors. For the group NIV SD&RD a MST of 18.3 months and 66.7% of long-term survivors were determined. Patients with recurrent tumors on this treatment protocol had an additional MST of 6.1 months. The total MST after first surgery was 16.2 months. The incidence of complications was low. Systemic complications were infrequent or rare. Retinal disturbances were seen in two patients; leukoencephalopathy was not seen in our patients. In 10% of patients cerebral complications were found, which were irreversible in 2% of patients. Complications could not be assigned unequivocally to the nitrosourea. These results compare favorably with what is reported in the literature, demonstrate the potential value of iaACNU in the treatment of malignant gliomas WHO Grade IV, and should encourage the initiation of a randomized clinical trial of adjuvant iaACNU in the therapy of these tumors. The authors propose iaACNU as a valuable approach in the management of primarily diagnosed malignant gliomas WHO Grade IV, but cannot recommend the delay of iaACNU until the recurrence of a brain tumor.

Monoclonal antibodies and immobilized antibodies. Patents and literature

Antibodies in both their free and immobilized state have been the object of considerable industrial and academic interest. A variety of methods are used for preparing and immobilizing antibodies. Applications for monoclonal antibodies include the preparation of therapeutics, diagnostics, and in affinity fractionation. Recent US patents on monoclonal and immobilized antibodies and scientific literature on monoclonal antibodies are surveyed. A description of these patents and a list of references are given.