Immunoglobulins
Constantin A. Bona, Francisco A. Bonilla in Textbook of Immunology, 2019
Precipitation and agglutination are conceptually identical. Precipitation involves soluble antigens and antibodies; agglutination denotes the formation of complexes of antibodies with relatively large particles such as bacteria, or erythrocytes (Figure 4–21). As does precipitation, agglutination requires antibody multivalence. Pentameric IgM is a good agglutinator, as well as a good precipitator. Not surprisingly, the same physicochemical factors influencing precipitation (antibody valence, reactant concentrations, pH, ionic strength, affinity, etc.) also affect agglutination. In addition, the density of antigenic determinants on the particle surface, as well as electrostatic interaction among the particles, will affect agglutination. For example, most cells have a net negative surface charge (the zeta potential) and tend to repel one another.
Immunological Tests for Diagnosis of Disease and Identification of Molecules
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Agglutination is an assay based upon the same principles as precipitation, but in it the antigen is a colloidal particle in suspension. Agglutination is widely used for blood typing. Agglutination, like precipitation, occurs in two stages. Antibody first reacts with antigenic determinants that are part of the large structure, such as red cells or bacteria (sensitization), and then forms bridges between antigenic determinants on adjacent cells to yield grossly visible clumps (agglutination). When antibody is in excess, a phenomenon known as the prozone may occur. In blood group work, for example, reactions of high titer antibodies with their antigens may appear to be weak or negative when undiluted serum is used but become strong with diluted serum. This is because while antibody binding does occur outside of the zone of equivalence, a lattice does not form and clumping cannot therefore occur. The process of formation of a lattice during agglutination is similar to the process which occurs in precipitation.
The Hematologic System and its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
Similar to the four major blood groups, blood can be classified on the basis of Rh factor, also called rhesus factor for the rhesus monkey in which the grouping was first discovered. Rhesus factor is a group of antigens that is found on the surface of red blood cells in about 85% of all people. Those who possess the factor are called Rh positive; those whose red blood cells lack the antigens are Rh negative. When an Rh negative person is exposed to Rh positive blood, the individual will develop antibodies to the antigen; on subsequent exposures, the antigen/antibody reaction will cause agglutination.
ABSTRACT
Published in Acta Clinica Belgica, 2018
L. Musger, V. Matheeussen, K. Loens, H. Goossens
Initial investigations included a blood differential performed on EDTA blood with both a liver and kidney functions assessment and an initial infectious serological screening performed on a serum collected on admission day. A Leptospira IgM rapid immunochromatographic test (Leptocheck, Zephyr Biomedicals) was performed on a serum specimen collected 5 days post-symptom onset. In addition, a Microscopic Agglutination Test (MAT) was carried out. Serum was brought into contact with 10 cultures of different Leptospira serotypes. Specific antibodies, present in the sample, will agglutinate and partly lyse the Leptospira. One drop of suspension was brought onto a slide and interpretation was done by dark field microscopy. All serological tests were performed at the Institute of Tropical Medicine (Antwerp, Belgium). Also, in CODA/CERVA laboratory, DNA was extracted from the same sample and challenged to a TaqMan PCR targeting the Hap1/LipL32 gene (diagnostic PCR). Positive PCR samples were further tested by lfb1 mono-gene targeted PCR for genotyping as previously described (3).
Digital microfluidics comes of age: high-throughput screening to bedside diagnostic testing for genetic disorders in newborns
Published in Expert Review of Molecular Diagnostics, 2018
David Millington, Scott Norton, Raj Singh, Rama Sista, Vijay Srinivasan, Vamsee Pamula
The first iteration of a near patient DMF platform was recently described [70] and consists of a small footprint instrument with a detachable mini-tablet user interface that utilizes single-use disposable assay cartridges. All buffers and reagents for the assay(s) are stored within the cartridge. Similar to larger format DMF instruments, this miniature DMF platform is capable of performing multiple enzyme formats (enzyme activity, immunoassays and molecular assays) and can multiplex several unique assays onto a single cartridge run. Hands-on effort for these tests involves only loading the sample (~50 μL of whole blood, urine or saliva) and initiating the cartridge from the tablet user interface. Notably, automated protocols are developed for plasma separation performed on the cartridge. Droplets of whole blood are added to an agglutination agent that promotes clumping of the red blood cells; the plasma portion of the sample subsequently responds to electrowetting while the solid portion does not. This difference in phase motility is exploited to isolate plasma for assays that require it.
Protective effect of myricetin, apigenin, and hesperidin pretreatments on cyclophosphamide-induced immunosuppression
Published in Immunopharmacology and Immunotoxicology, 2021
Mehmet Berköz, Serap Yalın, Ferbal Özkan-Yılmaz, Arzu Özlüer-Hunt, Mirosław Krośniak, Renata Francik, Oruç Yunusoğlu, Abdullah Adıyaman, Hava Gezici, Ayhan Yiğit, Seda Ünal, Davut Volkan, Metin Yıldırım
The level of humoral antibody production was evaluated by hemagglutinating antibody titer assay [15]. In order to induce an immune response, the animals were injected intraperitoneally with 100 µL freshly prepared SRBCs in 0.9% saline (0.5 × 109 cells) 4 d to prior sacrifice. The animals were sacrificed and blood samples were collected in sterile non-heparinized eppendorf tubes. After centrifugation at 5000 rpm for 15 min at 4 °C the serum was obtained. The serum samples from each group (25 µL) were serially diluted individually in 25 µL of 0.9% saline in microtitration plate. Then, 25 µL of 1% SRBC 0.9% saline was added to each well and mixed gently. The microtitration plates were held at room temperature for 1 h and the hemagglutination was observed visually, and then under a light microscope. The reciprocal of the highest dilution showing agglutination was taken as hemagglutination antibody titer.
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