Cellular-mediated immunity

Since cellular immunity results in the release of chemotactic lymphocytes that in turn enhance phagocytosis, a deficiency in cellular immunity may also result in chronic infections. Cellular immunity is mediated by T cells, macrophages, and NK cells involved in complex compensatory networks and secondary changes. Immunosuppressive agents may act directly by lethality to T cells, or indirectly by blocking mitosis, lymphokine synthesis, lymphokine release, or membrane receptors to lymphokines. In addition, cellular immunity is involved in the production and release of interferon, a lymphokine that ultimately results in blockage of viral replication (Table 15.4). Viruses are particularly susceptible to cytolysis by T cells since they often attach to the surface of infected cells. Thus, immunosuppression of any of the components of cellular immunity may result in an increase in protozoan, fungal, and viral infections as well as opportunistic bacterial infections. 

Immunization with peptide epitopes in adjuvant can elicit both antibody-and cellular-mediated immune responses that are able to provide protective immunity against a repertoire of targeted pathogens that have included viruses (1-4), bacteria (4-7), parasites (4,8-10), tumors (11-14), and self-hormones (4,15-18). However, a major problem associated with the use of subunit... 

Cell-Mediated Immunity (cellular immunity) (CMI) This uses T-leukocytes (natural killer cells, NK cells) to attack non-self cells. This includes cells infected by a microorganism and mutated cells that are abnormal and potentially harmful, which is the mechanism for preventing cancer after being exposed to a carcinogen. 

Pathogenesis of Type 1 Diabetes Mellitus Type 1 diabetes mellitus results from a cellular-mediated autoimmune destruction of the insuhn-secreting cells of pancreatic p-cells. In the vast majority of patients, the destruction is mediated by T cells. This is termed type lA or immune-mediated diabetes (Box 25-2). The a-, 8-, and other islet cells are preserved. The islet cells have a chronic mononuclear cell infiltrate, called insulitis. The autoimmune process leading to type 1 diabetes begins months or years before the clinical presentation, and an 80% to 90% reduction in the volume of the j3-cells is required to induce symptomatic type 1 diabetes. The rate of islet cell destruction is variable and is usually more rapid in children than in adults. 

Bolton WK, Tucker FL, Sturgill BC. New avian model of experimental glomerulonephritis consistent with mediation by cellular immunity. Nonhumorally mediated glomerulonephritis in chickens. J Chn Invest 1984 73(5) 1263-1276. 

Graber, C. D., Patrick, C.C. and Gal-phin, R. L. (1975) Light chain proteinuria and cellular mediated immunity in rifampin treated patients with tuberculosis. Chest, 67,408. 

Currently allergic reactions are classified into four types on the basis of different reaction patterns. Whereas types I—III are dependent on antibodies, the type IV reaction is mediated by cellular immune reactions. 

Delayed type hypersensitivty (DTH) reactions (synonym type IV allergic reactions) are exaggerated, T-lymphocyte mediated, cellular immune reactions to foreign substances, which require one to two days to manifest clinical symptoms. 

---