ABSTRACT
Cell-mediated immunity is mediated by T cells, which distinguishes it from immunity mediated by antibodies (humoral immunity). These terms evolved from the finding that immunity to certain antigens could be transferred to other animals by either cells, if they were of the same inbred strain, or antibodies. T cells have evolved to protect us against intracellular microbes (viruses and some bacteria) and to help B-cell (antibody) responses against extracellular microbes. They do this by monitoring the cells of the body for foreign antigens attached to MHC molecules.
