Q. What is the difference between schistocytes, spherocytes, and bite cells?

A. Schistocytes are fragmented red cells. You see them in microangiopathic hemolytic anemia.Their presence means that red cells are being ripped apart for some reason (and it’s important to find out that reason).

Spherocytes are ball-shaped red cells. They look smaller than regular red cells, and they don’t have a zone of central pallor. Their presence means that there is some sort of hemolysis going on (all hemolytic anemias can have spherocytes – they are formed by different mechanisms, all of which involve the loss of cell membrane but preservation of cell contents, so that the cell “rounds up” as described above).

Bite cells are present in G6PD deficiency. When you don’t have enough G6PD around, you can’t reduce toxic metabolites (like peroxides). When you’re exposed to an oxidant substance, you get lots of these nasty substances, and they start attacking the bonds between heme and globin. The globin chains break free and form a little ball that sticks to the inside of the cell membrane (this little ball is called a Heinz body). Macrophages in the spleen see these Heinz bodies and bite them out, forming “bite cells”.