You will get information about all the diagnostic tests that rely on the specific binding between an antigen and an antibody to detect or quantify a substance.
How ABO and Rh blood grouping works: forward (cell) versus reverse (serum) typing, why the two must agree, the Bombay phenotype trap, and how agglutination gives the result. Proced...
How radioimmunoassay measures tiny amounts of antigen: labeled and unlabeled antigen compete for limited antibody, so the radioactive signal falls as the sample's antigen rises. Pr...
How the indirect fluorescent antibody (IFA) test uses two antibodies to detect antibodies in patient serum (and antigens in cells). Principle, procedure, syphilis example, and why...
How the direct fluorescent antibody (DFA) test detects antigen directly in a specimen using one labeled antibody. Principle, step-by-step procedure, apple-green result, and the key...
Antigen detection tests identify pathogen proteins directly in blood, urine, stool, or CSF before antibodies appear. Learn the methods (ELISA, RDT, immunofluorescence, latex agglut...
The Coombs (antiglobulin) test explained: why direct detects antibody already on the patient's red cells and indirect detects antibody in serum, what a positive DAT means (warm vs...
Serological tests detect antibodies or antigens in patient serum to diagnose infections. This hub covers interpretation principles, seroconversion, the 9 key infections diagnosed s...
Widal test: principle, slide and tube procedure, result interpretation, diagnostic titers by region, false positives, limitations, and comparison with newer typhoid diagnostic test...
How the hemagglutination inhibition (HAI) test measures antiviral antibodies: antibody blocks the virus from agglutinating red cells, so no clumping means a positive result. Princi...
How to read and act on a Rose Bengal test for brucellosis: why the acidic pH matters, why a positive must be confirmed (especially in endemic areas), the prozone caveat, and where...
The Weil-Felix test explained: how Proteus OX-19, OX-2, and OX-K agglutination patterns point to typhus, spotted fever, or scrub typhus, why paired sera matter, and why a modern co...
The agglutination reaction explained by type: direct, indirect (passive), and reverse passive agglutination, plus latex agglutination, coagglutination, hemagglutination, and agglut...
Counterimmunoelectrophoresis (CIE) drives antigen and antibody toward each other in an agarose gel, producing a precipitin line within an hour. Learn the principle, why a neutral a...
ELISA (Enzyme-Linked Immunosorbent Assay) is the most widely used immunoassay for detecting antibodies and antigens. Learn all four ELISA types: direct, indirect, sandwich, and com...
The full framework of antigen-antibody reactions: the three stages of binding, and the main reaction types (agglutination, precipitation, complement fixation, neutralization, and l...
