What is the effect of adding sodium fluoride to the naphthyl ASD acetate (NASDA) esterase reaction?

Adding sodium fluoride to the naphthyl ASD acetate (NASDA) esterase reaction primarily serves to inhibit the esterase activity of monocytes. In this context, sodium fluoride acts as an inhibitor of the enzyme non-specific esterase, which is present in various cell types, but notably distinguishes between monocytes and other cells in hematological staining.

In the presence of sodium fluoride, monocytes will show a decreased or absent reaction in the NASDA test compared to granulocytes, which retain their reactive capabilities. This is crucial in diagnostic hematology as it helps in differentiating between these cell types based on the enzymatic activity. Hence, the impact of sodium fluoride specifically targets the monocytes, making this option the correct choice in understanding the mechanics of this specific staining method.