Low-Ionic-Strength Saline (LISS)
Definition
A reaction medium with reduced salt concentration used to enhance agglutination sensitivity, particularly for IgG antibodies. Lowering ionic strength reduces the electrostatic repulsion (zeta potential) that normally keeps red blood cells apart, allowing antibody-coated cells to come close enough for IgG to bridge them without requiring anti-globulin addition in some cases.
- Mechanism
- Reduces zeta potential between red cells
- Enhances
- IgG antibody detection sensitivity
- Common effect
- Shortens required incubation time
- Used in
- Blood group serology and agglutination testing
Common questions
Why does IgG normally struggle to agglutinate red cells without LISS?+
IgG molecules are too small to bridge the gap created by red cells' natural negative surface charge, so agglutination stays weak or absent unless something first reduces that repulsive distance.
What is the practical benefit of LISS in a serology workflow?+
It shortens the incubation time needed for sensitized cells to agglutinate and increases the chance of detecting weak antibodies, which is valuable in pre-transfusion cross-matching and antibody screening.
Related terms
- Agglutination Titre
- The reciprocal of the highest dilution of a serum or antigen solution at which visible agglutination still occurs. A titre of 1:64...
- Antiglobulin (Coombs) Test
- A two-stage assay that detects IgG antibodies bound to red blood cells. The direct test detects in-vivo cell-bound IgG; the indirect test...
- Hemagglutination
- Agglutination specifically involving red blood cells as the antigen-bearing particles. Direct hemagglutination occurs when antibodies bind surface antigens naturally present on red...
- Passive (Indirect) Agglutination
- An agglutination format in which a soluble antigen or antibody is adsorbed or covalently linked to a carrier particle (latex bead, tanned...
- Prozone (Hook) Effect
- A false-negative agglutination result caused by antibody excess. When antibody molecules outnumber antigen sites, each site is occupied by a single antibody...