Cellular agglutination

Agglutination Particulate or cellular Mainly qualitative Blood grouping Detection of antibodies... 

Agglutination. Bacterial cells may be aggregated by binding to antibodies that mask negative ionic surface charges and cros.s-link cellular structures (Fig. 7-8). The bacteria are thus immediately immobilized. This limits their ability to maintain an infection, but it forms a particulate matrix. This type of complex must also undergo elimination through the reticuloendothelial system. 

Nearly all current methods of isolation and purification of lectins rely on affinity chromatography. Naturally, the characteristic ligand must be determined in advance. The properties of lectins can be used to precipitate macromolecules and to agglutinate some types of cells, be they plant or animal. The driving force of this reaction is the association with certain bound residues, generally monosaccharides, from the macromolecule or the cellular periphery. When this type of reaction is observed, the problem is to find the sugar that can inhibit activity at the lowest possible molar concentration. As in the case of immunochemical precipitations, this inhibition is due to the occupation of the recognition site by the small soluble molecule. 

Antibodies can damage parasites directly, induce lysis, activate complement, agglutinate extracellular forms, stimulate antibody-dependent cellular cytotoxicity, and block their entry into their host cells. IgM, IgG, and IgA antibody isotypes are involved in these reactions. The isotype specificity not only depends on in which host compartment the parasite is residing (e.g., respiratory tree, GI tract, GU tract [IgA], bloodstream, lymphoid tissue [IgM, IgG]) but also on the antigens expressed during the different developmental stages and their chronicity. 

Lectins are cell-agglutinating and sugar-specific proteins. They are widely distributed and are involved in numerous cellular processes such as host-pathogen intervention, targeting of proteins within cells and cell-cell interactions. Major applications of lectins are ... 

Extracts from cohesive cells of four species of cellular slime mould Dictyostelium mucoroides, D. purpureum, D. rosarium, and Polysphondylium violaceum) agglutinated erythrocytes in a manner akin to D. discoideum. The lectin from Polysphondylium pallidum has been purified to homogeneity by adsorption onto formalinized erythrocytes it has a subunit of molecular weight 2.4 X 10 and appears to differ from the lectins isolated from other slime moulds. ... 

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