Gel precipitation technique
On this technique there is an interaction between two reagents and this interaction may result in a ring formation visible to the eye. Another reaction is between antigen and antibody combination on the technique the precipitation can quickly be explained by using agar gel. Several number of diffusion technique is available which are also used for examination such as; Immunoelectrophoresis, and immunodiffusion the technique of these diffusion are the same with that of are gel.
IMMUNODIFFUSION: this is a precipitation technique for examination and demonstration of antibody and antigen interaction. On these test, antibody and antigen is free to difuse toward each other. As the diffusion take place, so as the precipitation may also take place, these precipitation can only take place when antibody and the antigen meet in a high concentrations. This technique is used to detect diphtheria toxin in an Etek plate culture. The phenomenon take place by explaining toxin – antitoxin precipitation, shortly filter paper strip is inserted into the diphtheria solution, purity solution made up of 1000unit/ml of antitoxin is left to drain before it been place across the surface agar plate composed of 20% calf serum. Examined the organism with a known positive and negative strain are inoculated before they are incubated 35C for at list 24 – 48 hours. As toxin is made in this compound, it going to difuse into the line of agar in the then precipitation will take place at where the toxin meet antitoxin difusing from the strip in other to believed that the line of precipitation in the media is as a result of toxin, the line produce can be compared with a positive control.
IMMUNOELECTROPHORESIS: these technique is almost the same with one explained previously, but the movement of antigen in the technique is as a result of application of electric current via the used of counter current immunoelectrophoresis (CIE), it is this current that lead the antigen and antibody been persuaded toward each other in the gel, and this are used to explain the technique involved the explanation of celebrospinal fluid that are engulf with meningococcal or serum antibodies against fungal organism.