Cellular Immune Assays for Evaluation of Vaccine Efficacy

A greater understanding of the immune response, particularly of cell-mediated immune responses in malaria, tuberculosis (TB), human immunodeficiency virus (HIV), and cancer patients, will lead to improved vaccine design. Currently, in vitro analyses of cellular immune responses are being used for assessments of the efficacy of therapeutic and prophylactic vaccines, for clinical diagnosis, and for studies of immune regulation. This chapter was compiled by authors who have been involved in HIV vaccine testing for 15 years and have been collaborating with or have worked in laboratories in both developed and developing countries. When conducting cellular immunology assays, the integrity of the peripheral blood mononuclear cells (PBMC), especially the cellular membranes, is critical for success. In a separate experiment, the authors assessed the effect of the time from collection to processing on the proportions of lymphocyte subsets (total T cells, CD4 and CD8 T cells, B cells, and NK cells). The standard LPA measures antigen-induced cell division. Cells (usually PBMC) are incubated in the presence of various concentrations of an antigen (specific) or mitogen (nonspecific) stimulus of interest. The percentages of responders to mitogens, recall antigens, and HIV antigens were consistent for comparisons of fresh and cryopreserved PBMC. CD8+ T lymphocytes are able to mediate a variety of effector mechanisms and may provide the basis for protective immunity against a diverse array of infectious pathogens and tumors. The influences of host genes, health and nutrition status, and disease burden of patients are taken into consideration by conducting studies in-country.