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”.
So well explained! I have been researching on these subjects for a long time, but this is the first time I find clear explanations like this. I cannot see tabs to see your other subjects…?
Thanks for explaining that so well!
I was wondering, aren’t bite cells also seen in ß-thalassemia since they also contain heinz bodies?
No – there are no Heinz bodies in thalassemia. There are other inclusions caused by the aggregation of free alpha or beta chains (depending on whether you have beta or alpha thal) but they don’t get “bitten” out by the spleen for some reason!
Hi! Thank you for this explanation! I’m wondering why are bite cells not also formed in other kinds of spherocytosis. Isn’t the macrophage also taking “bites†out of cells in hereditary spherocytosis?
Good question!! In HS, the macrophages are eating pieces of membrane – but it’s more like tiny nibbles rather than big bites. In HS, the problem is membrane instability – so little pieces of membrane get floppy and get removed, and the cell just kinda rounds up. In G6PD deficiency, there’s a big ball of globin chains stuck to the inside of the red cell membrane – and the macrophage has to bite that thing out like a meatball, leaving a serious bite mark in the red cell!