A smear shows well stained anionic components, but WBCs are poorly stained. What is the most likely cause?

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Multiple Choice

A smear shows well stained anionic components, but WBCs are poorly stained. What is the most likely cause?

Staining with Wright-type dyes relies on a tightly buffered pH so that the basic dye component binds to negatively charged structures (like nuclei and basophilic granules) and the acidic dye binds to positively charged components (cytoplasm). If the stain solution is too acidic (low pH), the basic dye portion is not able to interact effectively with nuclear material, so WBC nuclei appear poorly stained. At the same time, anionic or acidophilic components that take up the acid dye can still appear well stained, giving a contrast where the WBCs look pale. Therefore, a stain that is too acidic is the most likely cause of well-stained anionic components with poorly stained WBCs. Ensure the stain buffer is around pH 6.4–6.8 for balanced staining.

Staining with Wright-type dyes relies on a tightly buffered pH so that the basic dye component binds to negatively charged structures (like nuclei and basophilic granules) and the acidic dye binds to positively charged components (cytoplasm). If the stain solution is too acidic (low pH), the basic dye portion is not able to interact effectively with nuclear material, so WBC nuclei appear poorly stained. At the same time, anionic or acidophilic components that take up the acid dye can still appear well stained, giving a contrast where the WBCs look pale. Therefore, a stain that is too acidic is the most likely cause of well-stained anionic components with poorly stained WBCs. Ensure the stain buffer is around pH 6.4–6.8 for balanced staining.

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