Describe in detail how a technician performs each of the following diagnostic tests with a sample of serum that contains specific antibodies, and indicate the advantages and disadvantages associated with each test .
(1) the complement fixation test,
(2) the fluorescent antibody test,
(3) the radioimmunoassay, and
the enzyme-linked immunosorbent assay.
The complement fixation test is used to detect antibodies for several types of viruses, fungi, and bacteria involves a two step process.. The first part or test system utilizes the patient’s serum, a preparation of antigen from the suspected pathogen, and complement from guinea pigs. The second part, the indicator system, uses sheep red blood cells and prepared antibodies that recognize the sheep red blood cells. The initial step involves heating the patient’s serum to destroy any existing complement in the serum. The antigen and guinea pig complement are then added to the serum, and then incubated at 37 degrees Celsius for 90 minutes. An antibody-antigen interaction occurs if there are antibodies specific for the antigen present. The complement is fixed, or used up, but there is no sign signifying that a reaction has taken place. After the indicator is added the tube is reincubated. If the complement was already fixed then the lysis of sheep red blood cells would not take place and the cells would remain intact. After the sample is centrifuged, a clear fluid with blood cells at the bottom is observed. It can be concluded that the patient’s serum contained antibodies. If the complement was not fixed, then the sheep cells will be available to react and they will lyse. After the sample is centrifuged, a red fluid with no intact blood cells at the bottom is observed and it can be concluded that the serum lacked antibodies. One advantage of the complement fixation test is that it can be used to detect a variety of antibodies by varying the antigen. Tests can be conducted for diseases such as encephalitis,...