- 1. The process by which suspended bacteria, cells, or other particles are caused to adhere and form into clumps; similar to precipitation, but the particles are larger and are in suspension rather than being in solution. For specific a. reactions in the various blood group s, see Blood Groups appendix. 2. Adhesion of the surfaces of a wound. 3. The process of adhering. [L. ad, to, + gluten, glue]- cold a. a. of red blood cells by their own serum (see autoagglutination), or by any other serum when the blood is cooled below body temperature, but most pronounced below 25°C; the phenomenon results from cold agglutinins; may be seen occasionally in the blood of apparently normal persons or as a pathologic finding in patients with primary atypical pneumonia, infectious mononucleosis, and other viral diseases, certain protozoan infections, or lymphoproliferative neoplasms. See autoagglutination.- false a. SYN: pseudoagglutination (1).- group a. a. by antibodies specific for minor (group) antigens common to several microorganisms, each of which possesses its own major specific antigen. SYN: cross a..- immune a. a. caused by antibody (agglutinin) that is specific for the suspended microorganism, cell, or for an antigen that has been coated on a particle of suitable size.- indirect a. SYN: passive a..- nonimmune a. 1. a. caused by a lectin having a degree of specificity for a particular sugar, the mechanism of which is not understood; 2. a. that results from nonspecific factors, as in the case of acid a. or spontaneous a..- passive a. a. of particles that have been coated with soluble antigen, by antiserum specific for the adsorbed antigen. SYN: indirect a..- spontaneous a. nonspecific clumping of organisms in saline related to lack of polar groups in electrolyte solution.
* * *ag·glu·ti·na·tion ə-.glüt-ən-'ā-shən n a reaction in which particles (as red blood cells or bacteria) suspended in a liquid collect into clumps and which occurs esp. as a serological response to a specific antibody
* * *(clumping)n.the sticking together, by serum antibodies called agglutinins, of such microscopic antigenic particles as red blood cells or bacteria so that they form visible clumps. Any substance that stimulates the body to produce an agglutinin is called an agglutinogen. Agglutination is a specific reaction; in the laboratory, sera containing different known agglutinins provide an invaluable means of identifying unknown bacteria. When blood of different groups is mixed, agglutination occurs because serum contains natural antibodies (isoagglutinins) that attack red cells of a foreign group, whether previously encountered or not. This is not the same process as occurs in blood coagulation.
* * *ag·glu·ti·na·tion (ə-gloo″tĭ-naґshən) [L. agglutinatio] 1. the action of an agglutinant substance. 2. the process of union in the healing of a wound. 3. the clumping together in suspension of antigen-bearing cells, microorganisms, or particles in the presence of specific antibodies (agglutinins). Called also clumping.
Agglutination occurring on addition of anti-human immunoglobulin to erythrocytes carrying antibody (A) and not occurring when it is added to erythrocytes lacking antibody (B).
Medical dictionary. 2011.