Howell-Jolly bodies and Heinz bodies are cellular inclusions found within erythrocytes (red blood cells). These inclusions result from different processes, but it can be difficult to figure out what those processes are, judging by their names alone! Here are a couple mnemonics that help me to keep things straight:
Howell-Jolly bodies are pieces of erythrocyte nucleus left over from the process of maturation (mature erythrocytes typically do not contain nuclei). For me, the name “Howell-Jolly” conjures up a mental gif: a howling fat, little baby who, when calmed by Mom, becomes quite jolly. The image of a baby may remind you that the Howell-Jolly body–a piece of nucleus–is a remnant of an immature, “baby”erythrocyte precursor cell.
I imagine that, because Howell-Jolly bodies are left over from a physiologic process, the spleen has evolved to remove these inclusion bodies from affected erythrocytes without permanently damaging those erythrocytes. Thinking clinically, we can expect to see Howell-Jolly bodies in a person without a functional spleen (eg, a patient with sickle cell disease).
Howell-Jolly bodies can be seen without a special stain, appearing as dark, round dots. You can continue using this mnemonic here by remembering that you usually do not have to go looking for a baby–parents seem to post photos of their kids on social media on a daily basis, and you sure know when a baby is howling on your flight (just don’t be that person staring daggers at Mom and Dad, they’re probably trying their best).
On the other hand, Heinz bodies are pieces of denatured globin chains. Some brief background biochem: Heinz bodies are formed when a cell does not have enough of the enzyme glucose-6-phosphate dehydrogenase (G6PD). G6PD reduces NADP to NADPH in a reaction that regenerates the antioxidant glutathione to its reduced state. In its reduced state, G6PD donates a hydrogen ion to toxic substances, like reactive oxygen species, making them less dangerous. In G6PD deficiency, damaged heme is recycled, but the denatured globin chains form little balls that attach to the erythrocyte membrane.
Here, the term “antioxidant” makes me think of colorful fruits and veggies, which are rich with antioxidants. One of my favorite fruits is the tomato, which is used to make Heinz ketchup. Macrophages in the spleen “bite” erythrocytes to remove these Heinz bodies, and the resulting cells are actually called bite cells! “Mmm, Heinz ketchup makes me want to take a bite of that burger/French fries/meatloaf!” Heinz bodies are created due to a pathological process, so the spleen seems to have trouble removing these inclusions without damaging affected erythrocytes.
Heinz bodies are not visible unless they are colored with a special stain. To continue the metaphor, you may have to go looking for ketchup when you are at your friend’s house or at a restaurant. Ketchup is great on French fries, but hopefully you aren’t posting pictures of yourself chugging a bottle of red sugar sauce on your Instagram. Nobody wants to see that.
Many thanks to Dr. Kristine Krafts at PathologyStudent.com for her helpful explanations.