Rapid identification of biological warfare agents using an instrument employing a light addressable potentiometric sensor and a flow-through immunofiltration-enzyme assay system.

An instrument employing a light addressable potentiometric sensor and a flow-through immunofiltration-enzyme assay system has been developed for the rapid and specific identification of biological warfare (BW) agents. The system has been designed to assay for up to eight agents simultaneously and provides an indication of the absence or presence of a threat within 15 min. Parameters affecting the mixing of the reagents within the instrument's fluidic lines were investigated and optimized. Measurements of blank samples and samples containing Bacillus subtilis spores in the concentration range of 10(4) to 10(6) cfu/ml indicate the limit of detection (LOD) is 3 x 10(3) cfu/ml for B. subtilus. Although the LOD is higher than that of several technologies currently under development, this instrument offers an immediate interim approach for addressing the need to rapidly detect biological warfare agents in the field.

Relationship of macrophage content, immunogenicity, and metastatic potential of a murine osteosarcoma of recent origin.

The purpose of these studies was to determine whether the high macrophage content (greater than 50 per cent) of the 90Sr-induced osteogenic sarcoma J (Os-J) of recent origin correlated with its immunogenicity or low metastatic potential. Cloning experiments demonstrated that the Os-J tumor is heterogeneous with regard to the production of experimental pulmonary metastases. Immunization-challenge studies in syngeneic mice and comparisons of tumor growth in normal or nude mice established that the slow growing Os-J tumor is poorly immunogenic. In vitro studies demonstrated that the Os-J tumor is highly susceptible to macrophages-mediated lysis. This may explain the slow growth of the tumor in normal recipients with an intact mononuclear phagocyte system, as compared with the more rapid emergence of tumors in macrophage-suppressed mice. However, spontaneous metastases of the Os-J tumor were not observed either in normal or macrophage-suppressed mice. Although a high macrophage infiltration of neoplasms could slow tumor growth, this was not associated with the immunogenicity of the neoplasm and did not appear to limit the spontaneous metastasis of this essentially benign neoplasm.

Tumor models to investigate the therapeutic efficiency of immunomodulators.

The development of successful approaches to immunotherapy is dependent on the proper consideration of the pathobiology of metastasis and a better understanding of the principles of biological response modification. Immunomodulation as a therapeutic modality has not proven notably effective in animals with preexistent palpable disease, an observation in agreement with the results from clinical protocols. Therefore, rather than developing experimental immunotherapy models of immunoprophylaxis or models with minimal tumor burden, we believe it more appropriate to develop models based on preexistent metastatic disease in a tumor-conditioned host. The most rigorous test of a biological response modifier's efficiency prior to clinical trials will be provided from immunotherapeutic trials of palpable autochthonous tumors.

The effect of experimental conditions on the assessment of T cell immunomodulation by biological response modifiers (thymosin fraction five).

The coculture of spleen cells with specific antigens in the presence of thymosin fraction five (F5) results in the stimulation of the lymphocyte response. To observe the stimulation, a suboptimal responder-to-stimulator ratio must be utilized. Suboptimal assay conditions also are needed in immunization challenge studies in which thymosin F5 acts as an effective immunoadjuvant. The data reported here suggest that to study the efficiency of a biological response modifier, suboptimal assay conditions are best for observation of immunomodulation. We also report that thymosin F5, in addition to exhibiting adjuvantlike activity for T cells, is stimulatory in assays of mixed lymphocyte response and in the in vitro stimulation of cytotoxic T effector cells, following a mixed lymphocyte-tumor culture.

Immunomodulation and therapeutic characterization of thymosin fraction five.

In this report we describe the characterization of the immunomodulatory efficiency and therapeutic properties of thymosin fraction five (F5). We consistently observed the immunostimulation of T-cell activity in assays of allogeneic mixed lymphocyte response (MLR) and the development of cytotoxic effector cells in an allogeneic mixed lymphocyte tumor response-cell-mediated cytotoxicity assay (MLTR-CMC). No induction of suppressor cell activity was observed. Thymosin F5 also acted successfully as an adjuvant when admixed with irradiated tumor cells. We were unable to demonstrate either NK cell or macrophage activation by thymosin F5. Therapeutic protocols using thymosin F5 and directed against pre-existing experimental and spontaneous metastases, had a significant immunotherapeutic potential.