IMMUNODIAGNOSIS (Latin immunis free, saved from something + diagnosis) — use of immunological methods for diagnosis of diseases or disturbances of protective functions of an organism. Methods I. are based on specific interaction of antigen with antibodies, sometimes in the presence of other (indicator) components of reaction. And. it is most widely applied in the field of infectious pathology, allergology, hematology, in oncology and at hemotransfusion, and also during the studying of transplant immunity and autoimmune diseases.
The immunodiagnosis of diseases is often connected with identification and identification of the antigens playing etiol or a pathogenetic role. Identification of antigens is important in And. infectious (bacterial, virus, fungal, parasitic) diseases. The bacteria allocated from an organism of the patient often identify in reactions agglutinations (cm), and immunofluorescence (see) with specific antiserums. For identification of viruses use the neutralization test registered or on braking hemagglutinations (see), caused by viruses, or on neutralization of their infectivity. The antigens which are in the dissolved state (e.g., the Australian antigen in serum of patients with hepatitis, antigens of dysenteric or cholera bacteria in excrements of patients), reveal in reactions precipitations (see), reactions of binding complement (see), braking of passive hemagglutination. In onkol, clinic for And. cancer of a liver and intestines use definition in serum of alpha-fetoprotein and other embryonic antigens by means of a method immunodiffusions (see). In modern endocrinology widely use radioimmunol. definition of insulin and other hormones.
Other direction I. consists in a research of an immune response on infectious, allergic and graft-specific antigens or own antigens at autoimmune diseases. The answer can be expressed in products of humoral antibodys or in formation of cellular immunity.
Definition of serumal antibodies — antibacterial, anti-toxic, antiviral and others — register by methods of a classical serology (see. Serological researches ): in an agglutination test (e.g., Vidal's reaction at a typhoid), passive agglutination with the erythrocytes or particles loaded with bacterial or fungal antigens, RSK, precipitations, neutralizations of viruses. The monovalent antibodies important in diagnosis hron of infections, define in Koombs's test with antiglobulinovy serum (see. Koombs reaction ). Toksinneytralizuyushchy antibodies reveal also in vivo by intradermal introduction of small doses of toxin (test of Chic at diphtheria, test Is wild at scarlet fever). In allergology use skin tests with allergens (see. Skin tests ). Emergence of skin reaction of immediate type indicates existence at the patient of IgE-antibodies (reagins) specific to this allergen. Sometimes skin tests with allergens put in passive option — Prausnitts's test — Kyustnera (see. Prausnittsa-Kyustnera reaction ). Methods I., napr, using limfotsitotoksichesky antibodies, use in transplantation immunology at fabric typing of the donor and recipient on antigens of histocompatability.
In addition to identification of specific antibodies, for And. some diseases use determination of amount of serumal immunoglobulins as an indirect indicator of development of an immune response. So, increase in the IgA and IgM level in serum of the newborn indicates a pre-natal infection — syphilis, Toxoplasmosis and so forth, increase in IgE — the allergic nature of a disease. Identification in serum homogeneous on structure and antigenic properties of immunoglobulin (monoclonal) plays a large role in And. gammaglobulinopatiya, e.g. Valdenstrema disease (see), multiple myeloma (see).
V I. autoimmune diseases the important place is taken by definition of serumal autoantibodies: a rhematoid factor at a pseudorheumatism and other collagenoses, antibodies to kernels of cells at a system lupus erythematosus, anti-erythrocyte antibodies at autoimmune anemias.
The immune shifts concerning cellular immunity investigate or in vivo by means of the skin tests revealing hypersensitivity of the slowed-down type (e.g., reactions of the Tuberculine test and to Mant at tuberculosis), or in vitro by tests for ability of lymphocytes to a blastotransformation at contact with antigen; define also ability of lymphocytes to products of the factor which is slowing down migration of macrophages (MYTH) that is an equivalent of hypersensitivity of the slowed-down type.
The immunodiagnosis of disturbance of immunological functions of an organism is based on a research of nonspecific immune responses and functions of specific humoral and cellular immunity.
For assessment of nonspecific immune responses investigate ability of polymorphonuclear phagocytes (neutrophils) to migration under the influence of chemotactic factors, to absorption of corpuscular antigens, to their intracellular digestion. Also definition of a complement of serum, including its separate components is important.
Decrease in nonspecific immune responses can depend on genetic defects, delay of rates of immune maturing, an adverse effect of diseases (diabetes), intoxications (alcoholism).
For assessment of functions of humoral specific immunity determine the level of serumal immunoglobulins of different classes, level of normal antibodies — isohemagglutinins, antibodies to the viral antigens extended bacterial or ability to antibodyformation at immunization by various vaccines used as test antigens.
The specified methods allow to diagnose primary immunodeficiency (an inborn agammaglobulinemia, various dysgammaglobulinemias) and secondary immunodeficient diseases arising owing to disturbance of synthesis of immunoglobulins (e.g., at limfoproliferativny diseases) or strengthenings of their catabolism (at a thyrotoxicosis, a nephrotic syndrome). Definition of antibodyformation on test antigens allows to reveal a state immunol, areactivity at datum level of immunoglobulins.
For assessment of functions of cellular immunity investigate reactions of hypersensitivity of the slowed-down type to intradermal or hypodermic administration of various antigens (tuberculine, fungal antigens) and ability of lymphocytes to transformation and proliferation under the influence of nonspecific mitogenetic stimulators (e.g., phytohemagglutinin). Reaction is estimated on intensity of a blastotransformation, in size of a mitotic index or on inclusion of radioactive precursors of RNA and DNA.
The research of cellular immunity is necessary for diagnosis of the immunodeficiency connected with insufficiency of system of T lymphocytes.
A variety of the tasks solved with the help And., high sensitivity and specificity of its methods define wide use And. in different areas a wedge, medicine.
Bibliography: Ioffe V. I. Clinical and epidemiological immunology, L., 1968, bibliogr.; Petrov R. V. Immunology and immunogenetics, M., 1976, bibliogr.; Modern problems of immunology and an immunopathology, under the editorship of A. A. Smorodintsev, etc., JI., 1970; Bellanti J. A. Immunology, Philadelphia, 1971; R about i t t I. M. Essential immunology, Oxford, 1971.
E. B. Chernokhvostova.