This azide-free, formaldehyde-free, biodegradable cleaner contains a proteolytic enzyme that aids in the removal of protein buildup in the sensing orifices of a hematology analyzer. Blood proteins flowing through blood counting orifices (apertures) in a hematology analyzer over time accumulate around these openings to a point that the size of the orifices are minimized and eventually blocked. The proteolytic enzyme in the cleaning agent reacts with and dissolves the protein in and around the apertures.