| 摘要 |
A sensitive direct immunoassay system is provided for the detection of an antigen in body fluids. A single antibody which reacts with an antigen or antigens and which is bonded to an insoluble member, is incubated with a test sample. During this first period of incubation a portion of an antigen present in the test sample will combine with the antibody immobilized on the insoluble member. The antibody bonded member, to which antigen is attached, is then washed and incubated with an enzyme tagged antibody reagent. During the second incubation, the tagged antibody reacts with antigen fixed to the antibody member in the first incubation. Thus, an immobilized "sandwich" is formed of an insoluble member- antibody-antigen-enzyme tagged antibody. After the second incubation, the member is washed again to remove unreacted enzyme antibody reagent. The member is then exposed to a substrate which is converted by the enzyme to produce an end product. The tagged antibody reagent will be fixed in the second incubation only if antigen was present in the sample. The amount of enzyme tagged antitbody fixed is proportional to the amount of antigen or antigens present in the test sample up to the maximum capacity of the test. The concentration of the end product, and hence the amount of antigen or antigens, is determined by a spectrophotometer which measures the optical absorption of light by the end product. This readout is then compared against a standard value for both antigen negative and antigen positive samples.
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