Agglutination and rouleaux are both phenomena involving red blood cells (RBCs), but they differ in their underlying causes and appearance.
| Feature | Rouleaux | Agglutination |
|---|---|---|
| Appearance | Orderly linear stacks of RBCs | Grapelike aggregates of RBCs |
| Cause | Increased plasma proteins (e.g., globulins, fibrinogen) reducing the zeta potential. | Antibody-antigen interaction on RBC surface |
| Reversibility | Dispersed with saline dilution | Persists with saline dilution |
| Clinical Significance | Can be normal; may indicate inflammation | Usually indicates an immune-mediated process |
Detailed Explanation:
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Rouleaux Formation: Rouleaux occur when RBCs stack together like coins.
- This is primarily due to increased concentrations of certain proteins (e.g., globulins or fibrinogen) in the plasma.
- These proteins reduce the negative charge (zeta potential) on the surface of RBCs, allowing them to come closer and stick together.
- Rouleaux formation can be normal in some cases, but it can also be associated with inflammatory conditions or multiple myeloma.
-
Agglutination: Agglutination refers to the clumping of RBCs.
- It is caused by antibody-antigen reactions on the RBC surface.
- Specific antibodies bind to antigens on different RBCs, forming bridges that link the cells together.
- Agglutination is usually indicative of an immune-mediated process, such as autoimmune hemolytic anemia or transfusion reactions.
Saline Dilution Test:
A saline dilution test can help differentiate between rouleaux and agglutination. According to the reference, this test is useful to differentiate between rouleaux and agglutination:
- In rouleaux, the stacks of RBCs will typically disperse when the blood sample is diluted with saline.
- In agglutination, the clumps of RBCs will persist even after saline dilution.
