Response immune

Section 25 16 Carbohydrates and proteins that are connected by a chemical bond are called glycoproteins and often occur on the surfaces of cells They play an impor tant role m the recognition events connected with the immune response... 

Contamination of blood products with lymphocytes can lead to transfusion-induced reactions ranging from a mild fever to severe reactions such as alloimmunization and graft versus host disease (GvHD), in which the transfused lymphocytes (graft) survive the defensive immune reaction of the patient (host) and start a reaction which destroys the cells of the host. The patient also may develop an immune response to the human leukocyte antigen (HLA) type of the graft s cells and reject all platelet transfusions that do not match their own HLA system. The HLA system, found on blood platelets and lymphocytes, is more compHcated than, but similar to, the ABO blood group system of red cells. 

Interferons (lENs) (52,53), a family of species-specific vertebrate proteins, confer nonspecific resistance to a broad range of viral infections, affect cell proliferation, and modulate immune responses. AH three principal interferons, a-interferon (lEN-a) produced by blood leucocytes, P-interferon (lEN-P) by fibroblasts, and y-interferon (lEN-y) by lymphocytes, also have antiviral activity. The abiUty of interferons to inhibit growth of transplantable and carcinogen-induced tumor led to research showing the direct antiproliferative and indirect immune-mediated antitumor activities (see Chemotherapeutics, anticancer). IENs have been found to be efficacious in certain malignancies and viral infections, eg, hairy cell leukemia (85% response) and basal cell carcinoma (86% response). However, the interferons do have adverse side effects (54). 

The active immunotherapeutic approach is specific and based on the premise that tumor antigens are immunogenic and the host is sufficientiy immunocompetent to mount an effective immune response to an autologous tumor. Theoretically, a weak or suppressed host immune system that had allowed the formation of a tumor may be overridden by active immunization or immunostimulation. In practice, vaccines composed of so-called autologous tumor extracts have been used to treat patients with malignant melanoma (73), and purified melanoma tumor-associated antigens have been used to ehcit antibody responses in melanoma patients (74). 

Vitamin E [59-02-9] C2c,H q02, has been studied for its potential to modulate prostaglandin metaboHsm and alter immune response in aged mice. 

Finally, in another study related to nutrition and the immune response in the aged, old mice were given oral doses of two amino acids (qv), lysine and arginine. The treated mice showed evidences of recovered mitogenic responsiveness, expression of T-ceU markers, and production of thymic semm factor (thymulin). The effect of the amino acid combination, sold commercially as Neoiodarsolo, seems to consist mainly of the reactivation of the... 

Live vaccines are normally weakened strains that do not cause diseases in the host, but stiU can stimulate the immune response. A typical example is the poho vaccine. The weakening of microorganisms or attenuation of the vims or bacteria can be accompHshed by passage through different substrates and/or at different temperatures. Modem genetic engineering techniques can also be used to attenuate a vims or bacterium. 

Adjuvants are substances which can modify the immune response of an antigen (139,140). With better understanding of the functions of different arms of the immune system, it is possible to explore the effects of an adjuvant, such that the protective efficacy of a vaccine can be improved. At present, aluminum salt is the only adjuvant approved for use in human vaccines. New adjuvants such as QS-21, 3D-MPL, MF-59, and other liposome preparations are being evaluated. Several of these adjuvants have been in clinical trial, but none have been approved for human use. IL-12 has been proposed as an adjuvant which can specifically promote T-helper 1 ceU response, and can be a very promising adjuvant for future vaccine development. 

In 1971, levamisole, an anthelmintic compound widely used in catde and swine, was shown to improve the effects of an experimental Brucella abortus vaccine in mice. Since that time, the veterinarians and physicians have explored the effects of levamisole in such diverse areas as arthritis, lupus erythematosis, cancer therapy, respiratory diseases, Newcastle disease, foot-and-mouth disease, mastitis, and vaccine potentiation. Although the exact mechanism of action has as yet not been deterrnined there is substantial evidence that, under defined circumstances, levamisole can augment the animal s natural immune response (9). New immunostimulants include Staph Ijysate acemannon, NLAB-31. 

The recommended daily allowance for vitamin E ranges from 10 international units (1 lU = 1 mg all-rac-prevent vitamin E deficiency in humans. High levels enhance immune responses in both animals and humans. Requirements for animals vary from 3 USP units /kg diet for hamsters to 70 lU /kg diet for cats (13). The complete metaboHsm of vitamin E in animals or humans is not known. The primary excreted breakdown products of a-tocopherol in the body are gluconurides of tocopheronic acid (27) (Eig. 6). These are derived from the primary metaboUte a-tocopheryl quinone (9) (see Eig. 2) (44,45). 

Insufficient zinc results in slowed growth, delayed wound healing, poor appetite, mental lethargy, and sexual immaturity and it interferes with the immune response. The main function of zinc in metaboHsm is enzymatic and there is evidence of other physiologic roles, eg, in stabilization of membrane stmcture (57). 

Research on an hCG vaccine has been conducted over the past 15 years. WHO has conducted a phase I clinical study in AustraUa, using a vaccine based on a synthetic C-terminal peptide (109—141) of P-hCG conjugated to Diptheria Toxoid (CTP-DT), that showed potentially effective contraceptive levels of antibodies were produced in vaccinated women without any adverse side effects. Phase II clinical studies are under consideration to determine if the immune response, raised to its prototype anti-hCG vaccine, is capable of preventing pregnancy in fertile women volunteers (115). While research on the C-terminal peptide from the P-subunit of hCG has been carried out under the auspices of WHO, research supported by the Population Council and the National Institutes of Health has involved two alternative vaccine candidates (109,116,118). 

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