Tuberculin reaction

IV Cell-medi- Antigens cause activation of lym- 24-48 Tuberculin reaction... 

Tuberculin skin testing is an important part of the care of all HIV-1-infected patients or persons at risk for HIV-1 infection. Tuberculin skin testing should be done using the Mantoux method. A tuberculin reaction of >5 mm of induration is classified as positive in persons known to have or suspected of having HIV-1 infection. Unfortunately, as the CD4 lymphocyte count declines with progression of HIV-1 disease, many patients no longer react to delayed-type hypersensitivity testing. More than 60% of persons with CD4 lymphocyte counts of <200 cells/pl may have skin test reactions of <5 mm. Thus, it is impossible to detect the presence of tuberculous infection in many HIV-l-infected individuals. 

Three characteristic biological reactions can be ascribed to special polysaccharide components of M. tuberculosis. These are the typical skin reaction, usually termed the tuberculin reaction, certain cellular reactions, and the specific precipitin reaction. 

Boughton B, Spector WG. Histology of the tuberculin reaction in guinea pigs. J Pathol Bacteriol 1963 85 371-381. 

Hypersensitivity Reactions Tuberculin reaction in the BCG-infected guinea-pig... 

Despite some discordant data , it seems that phenylbutazone does not affect the tuberculin reaction in BCG-infected guinea-pigs > . 

Mention should be made at this juncture of the role of adrenolytic drugs as inhibitors of inflammation. Spector and Willoughby found that diben-amine hydrochloride antagonizes the anti-inflammatory effect of iproniazid, but other workers have shown that adrenolytic drugs themselves reduce capillary permeability , and that dibenamine hydrochloride suppresses the tuberculin reaction in the guinea-pig . 

It was at the University of Pennsylvania that Seibert began her important work in tuberculosis research. Robert Koch had reported as early as 1891 that animals previously infected with tuberculosis had a unique reaction when tuberculosis bacteria fragments or dead bacteria were injected under the sldn. The culture extract used by Koch and others was called tuberculin, and the appearance of welts in response to the injection was called the tuberculin reaction. The reaction is due to an immune response known as delayed hypersensitivity and appears in humans who have either active tuberculosis infections or who have had active infections in the past. It is thus valuable to public health officials for identifying potential tuberculosis carriers. The preparations of tuberculin prepared by Koch and others, however, were complex mixtures of many substances, including the presumed active protein component, and the contents were not consistent from batch to batch. Thus the ability to induce the tuberculin reaction varied enormously from preparation to preparation. 

Seibert devised a way to purify a protein causing the tuberculin reaction, which allowed standardization of strength from one preparation to another. She published her first work on purification of tuberculin in 1934. The... 

Examples Allergic rhinitis, asthma, systemic anaphylaxis Some drug allergies (eg.. penicillin) Serum sickness, Arthus reaction Tuberculin reaction, contact dermatitis (with IVc) Chronic asthma, chronic allergic rhinitis Maculopapular exanthema with eosinophilia Contact dermatitis, Maculopapular and bullous exanthema, hepatitis AQEP Beh t disease... 

Morbilliform exanthema, fixed drug eruptions, and erythrodermia are thought to result from a cell-mediated reaction, i.e., T-lymphocytes as in contact sensitivity. However, the histologic pictures of both reactions differ in a number of features. Moreover, basophil infiltration, which is rather important in contact sensitivity, is often negligible in the tuberculin reaction. In spite of several differences between... 

Allergy a hypersensitivity of the immune apparatus s pathological immune reaction induced either by antibodies (immediate hypersensitivity) or by lymphoid cells (delayed type A.). Unlike the delayed type, immediate hypersensitivity can be passively transmitted in the serum. Symptoms of immediate hy-peisensitivity begin shortly after contact and decay rapidly, but delayed type symptoms do not attain a maximum for 24-48 hours then decline slowly over days or weeks Examples of immediate type A. are anaphylaxis the Arthus reaction and serum sickness. The best known A., anaphylaxia, can occur as a local (cutaneous) reaction (e.g. a rash with blisters) or as a systemic reaction (anaphylactic shock). Asthma, hay fever and nettle rashes are also examples of local anaphylactic reactions which are induced by reagins (see Immunoglobulins IgE). Only primates can be sensitized by injection with human reagins. An example of delayed type A. is the tuberculin reaction, which is based on a cellular immune response. 

Coombs and Gell (1963) have classified all immunologic (allergic) reactions into four types (I to IV). The classification of Types I to III depends on whether antigen or antibody is cell-fixed or in solution. Type IV is cell-mediated and is typified in the skin by responses such as the tuberculin reaction which develops macroscopically over 36-48 hr and lasts for 72-96 hours. This is the classical delayed hypersensitivity reaction. 

Hypersensitivity Reactions Tuberculin reaction in the BCG-infected guinea-pig Since there is a close relationship between connective tissue disorders and auto-immune diseases on the one hand, and delayed hypersensitivity on the other, it has been suggested that delayed hypersensitivity reactions offer... 

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