Question:medium
Prozone phenomenon is seen with?
Prozone phenomenon is seen with?
Show Hint
A false negative from too much antibody at low dilutions; dilute the serum and it turns positive.
Updated On: Jun 24, 2026
- Same concentration of antibody and antigen
- Antigen excess to antibody
- Antibody excess to antigen
- Hyperimmune reaction
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Serological clumping tests depend on building a network between antigen and antibody. If the ratio of the two is off, the network fails and the test reads negative even when antibody is present.
Step 2: Picture a test where the patient serum is loaded with antibody but only a little antigen is around. Every antigen molecule gets saturated by separate antibody arms, so no bridging lattice develops and the tube looks clear. This deceptive negative caused by too much antibody is exactly the prozone effect, pointing to option c.
Step 3: The mirror situation, where antigen swamps antibody, also blocks lattices but is named the postzone, not prozone. Equal balance of the two reactants gives maximal visible agglutination, which is the zone of equivalence.
Step 4: The classic fix is to serially dilute the serum, lowering antibody until equivalence is reached and the reaction reappears, proving antibody excess was the culprit.
\[\boxed{\text{Antibody excess to antigen}}\]
Step 2: Picture a test where the patient serum is loaded with antibody but only a little antigen is around. Every antigen molecule gets saturated by separate antibody arms, so no bridging lattice develops and the tube looks clear. This deceptive negative caused by too much antibody is exactly the prozone effect, pointing to option c.
Step 3: The mirror situation, where antigen swamps antibody, also blocks lattices but is named the postzone, not prozone. Equal balance of the two reactants gives maximal visible agglutination, which is the zone of equivalence.
Step 4: The classic fix is to serially dilute the serum, lowering antibody until equivalence is reached and the reaction reappears, proving antibody excess was the culprit.
\[\boxed{\text{Antibody excess to antigen}}\]
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