Partial antigens

The allergic variety of contact dermatitis is a type IV hypersensitivity response involving sensitization of T lymphocytes. Antigens form after the sensitizing substance (haptens or partial antigens) comes into contact with the dermal protein fc>r the first time, which results in sensitization. Sensitization may take weeks to years to develop. On reexposure to the same or a related substance, a delayed inflammatory response is elicited, usually within 48 to 72 hours. Allergic contact dermatitis is often associated with the eyelids or periocular area and in some instances may involve the face and the hands. 

Up to this point we have been concerned primarily with so-called complete antigens, substances which both stimulate antibody production and react with the antibody so formed. Other substances, however, have a more limited antigenicity—e.g., while they react specifically with antibody, they are unable to stimulate antibody formation. These substances are partial antigens or haptens. The use of immunological and serological... 

Groups Reference strain C.C. UEM Partial antigens O-antigen relationship (Remarks)... 

By similar logic, protein affinity Hbraries have been constmcted to identify protein—protein combining sites, as in antibody—antigen interaction (19) and recombinant Hbraries have been made which produce a repertoire of antibodies in E. coli (20). In another case, a potential DNA-based therapeutic strategy has been studied (21). DNAs from a partially randomized Hbrary were selected to bind thrombin in vitro. Oligonucleotides, termed aptamers that bound thrombin shared a conserved sequence 14—17 nucleotides long. 

Mechanism of peripheral immune tolerance characterized by a state of functional unresponsiveness induced in T cells by suboptimal or partial stimulation. Engagement of the antigen receptor in the absence of costimulation signaling induces anergy in T cells, which become unable to respond to new stimulations. 

The first heteropolysaccharide for which a cyclic structure has been proposed is the enterobacterial common antigen (ECA), which was shown by f.a.b.-m.s. to be a mixture of three cyclic components containing 4, 5, and 6 repeats, respectively, of a previously characterized trisaccharide (31) in which the GlcNAc residues were known to be partially acetylated at 0-6. 

The inflammatory response in UC is propagated by atypical type 2 helper T cells that produce proinflammatory cytokines such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor (TNF).7 As discussed previously, a genetic predisposition to UC may partially explain the development of excessive colonic and rectal inflammation. The finding of positive perinuclear antineutrophil cytoplasmic antibodies (pANCA) in association with the human leukocyte antigen (HLA)-DR2 allele in a large percentage of patients with UC supports this theory.4,12... 

Gold, A.M., Despommier, D.D. and Buck, S.W. (1990) Partial characterization of two antigens secreted by Li larvae of Trichinella spiralis. Molecular and Biochemical Parasitology 41, 187-196. 

On patients with cancer, the effects of green tea catechins, soy isoflavones and quercetin as chemoprotective/chemotherapeutic agents have also been studied. Although results have not been entirely satisfactory, a partial response has been achieved in some trials. For example, small decreases in plasma concentration of prostate-specific antigen were observed in prostate cancer patients who consumed soy isoflavones. Nevertheless, results in individuals with premalignant disease who consumed green tea polyphenols support their advancement into phase III clinical intervention trials aimed at the prevention of PIN, leukoplakia, or premalignant cervical disease (Thomasset and others 2006). 

An example of an immunoassay format is shown in Figure 3. This immunoassay format relies on partial saturation of the solid-phase antibody (Ab) by the antigen (Ag) and on its competition with the labeled antigen (Ag-L) for the available antibody sites. At low antibody and tracer concentrations the sensitivity of... 

IL-2-stimulated cytotoxic T cells appear even more efficacious than LAK cells in promoting tumour regression. The approach adopted here entails removal of a tumour biopsy, followed by isolation of T-lymphocytes present within the tumour. These tumour-infiltrating lymphocytes (TILs) are cytotoxic T-lymphocytes that apparently display a cell surface receptor which specifically binds the tumour antigen in question. They are thus tumour-specific cells. Further activation of these TILs by in vitro culturing in the presence of IL-2, followed by reintroduction into the patient along with IL-2, promoted partial/full tumour regression in well over 50 per cent of treated patients. 

The presence of tumour-specific antigens implies that the immune system should be capable of recognizing and destroying transformed cells. This concept, known as immunosurveillance, probably does function to some extent in the body. The immune system does respond to the presence of some tumours, causing their partial or complete regression. The major anti-tumour immune elements include ... 

Baseline laboratory tests should include complete blood cell count, prothrombin time, activated partial thromboplastin time, liver and renal function tests, and serum carcinoembryonic antigen (CEA). Serum CEA can serve as a marker for monitoring colorectal cancer response to treatment, but it is too insensitive and nonspecific to be used as a screening test for early-stage colorectal cancer. 

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