Surveillance Study of Influenza Occurrence and Immunity in a Wisconsin Cohort During the 2009 Pandemic.

Background: Antibody and T-cell immunity to conserved influenza virus antigens can protect animals against infection with diverse influenza strains. Although immunity against conserved antigens occurs in humans, whether such responses provide cross-protection in humans and could be harnessed as the basis for universal influenza vaccines is controversial. The 2009 pandemic provided an opportunity to investigate whether pre-existing cross-reactive immunity affected susceptibility to infection.

ELISPOT Assay for Monitoring Cytotoxic T Lymphocytes (CTL) Activity in Cancer Vaccine Clinical Trials.

The profiling and monitoring of immune responses are key elements in the evaluation of the efficacy and development of new biotherapies, and a number of assays have been introduced for analyzing various immune parameters before, during, and after immunotherapy. The choice of immune assays for a given clinical trial depends on the known or suggested immunomodulating mechanisms associated with the tested therapeutic modality. Cell-mediated cytotoxicity represents a key mechanism in the immune response to various pathogens and tumors.

Immunological monitoring of the tumor immunoenvironment for clinical trials.

Monitoring of immunotherapeutic clinical trials has undergone a considerable change in the last decade resulting in a general agreement that immune monitoring should guide the development of cancer vaccines. The emphasis on immune cell functions and quantitation of antigen-specific T cells have been playing a major role in the attempts to establish meaningful correlations between therapy-induced alterations in immune responses and clinical endpoints. However, one significant unresolved issue in modern immunotherapy is that when a tumor-specific cellular immune response is observed following the course of immunotherapy, it does not always lead to clinically proven cancer regression.

Application of a flow cytometric cytotoxicity assay for monitoring cancer vaccine trials.

In this study, we evaluated the applicability of a flow cytometry-based cytotoxicity (FC) assay previously developed by our laboratory, for monitoring cancer vaccine trials. The assay simultaneously measures effector cell degranulation and target cell death. Clinically relevant samples consisted of frozen peripheral blood mononuclear cells (PBMC) from vaccinated melanoma patients with known response to the melanoma peptide g209.

New approaches for monitoring CTL activity in clinical trials.

We have developed a modification of the ELISPOT assay that measures Granzyme B (GrB) release from cytotoxic T lymphocytes (CTLs). The GrB ELISPOT assay is a superior alternative to the 51Cr-release assay since it is significantly more sensitive and provides an estimation of cytotoxic effector cell frequency. Additionally, unlike the IFN-gamma ELISPOT assay, the GrB ELISPOT directly measures the release of a cytolytic protein.

DNAse treatment following thawing of cryopreserved PBMC is a procedure suitable for lymphocyte functional studies.

Testing freshly isolated PBMC is not practical for immune monitoring analysis in large clinical trials or natural history studies. Thus, cryopreserved PBMC represent a more practical alternative. However, cell clumping is a common problem following thawing of PBMC isolated from blood that was previously transported and stored.

Application of the granzyme B ELISPOT assay for monitoring cancer vaccine trials.

Granzyme B (GrB) is present in the granules of cytolytic lymphocytes and is a key mediator of cell-mediated target cell death via the granule-mediated pathway. The release of GrB can be used as an indicator of a cytotoxic T lymphocyte response. Herein, we report that the GrB enzyme-linked immunospot assay (ELISPOT) can be used to measure ex vivo antigen-specific cytotoxicity of peripheral blood mononuclear cells from cancer patients vaccinated with a peptide-based cancer vaccine.

A novel flow cytometric assay for evaluating cell-mediated cytotoxicity.

Comprehensive evaluation of cell-mediated cytotoxicity is very important, especially in the clinical setting, when a surrogate immunologic endpoint that correlates with a clinical outcome needs to be defined. With the objective of simultaneously evaluating target cell death and effector cell frequency, the authors combined the measuring of the expression of the degranulation marker CD107a by effector cells with the apoptosis marker annexin V binding to target cells. Using human cytotoxic T lymphocytes, the authors found a significant incubation time-dependent increase of surface CD107a expression on effector cells due to degranulation.

Evaluating the cytotoxicity of innate immune effector cells using the GrB ELISPOT assay.

BACKGROUND: This study assessed the Granzyme B (GrB) ELISPOT as a viable alternative to the 51Cr-release assay for measuring cytotoxic activity of innate immune effector cells. We strategically selected the GrB ELISPOT assay because GrB is a hallmark effector molecule of cell-mediated destruction of target cells. METHODS: We optimized the GrB ELISPOT assay using the human-derived TALL-104 cytotoxic cell line as effectors against K562 target cells.

A modified human ELISPOT assay to detect specific responses to primary tumor cell targets.

BACKGROUND: The desired outcome of cancer vaccination is to induce a potent T cell response which can specifically recognize and eliminate autologous tumor cells in vivo. Accordingly, immunological assays that demonstrate recognition of native tumor cells (tumor-specific) may be more clinically relevant than assays that demonstrate recognition of tumor protein or peptide (antigen-specific). METHODS: Towards this goal, we adapted the IFN-gamma ELISPOT assay to measure immune responses against autologous primary tumor cells in vaccinated cancer patients.

The Granzyme B ELISPOT assay: an alternative to the 51Cr-release assay for monitoring cell-mediated cytotoxicity.

BACKGROUND: The interferon-gamma (IFN-gamma) ELISPOT assay is one of the most useful techniques for immunological monitoring of cancer vaccine trials and has gained increased application as a measure of specific T cell activation. However, it does not assess cell-mediated cytotoxicity directly as IFN-gamma secretion is not limited to only cytolytic cells. Granzyme B (GrB) is a key mediator of target cell death via the granule-mediated pathway.