It's mentioned in my textbook that subjects with sickle cell trait develop resistance to malaria. I've read a few research papers predisposing involvement of macrophages and papers asserting involvement of the heme oxygenase system rendering me confused; so what actually causes this resistance. And is this resistance also present in the subjects with sickle cell anemia? Also some African tribes are generally mutated to provide malaria resistance. See this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3499995/
I would say that there are at least 2 explanations:
- Higher levels of free heme in the blood of individuals with sickle cell anaemia/sickle cell anaemia trait. Free heme is toxic to Plasmodium.sp Science. 1981 Nov 6;214(4521):667-9., detailed mechanism is described here: J Mol Med (Berl). 2008 Oct;86(10):1097-111. This effect is also observed in people with other diseases affecting stability of erythrocyte's membrane, such as thalasemia or spherocytosis.
- It is also possible that, when erythrocyte's membrane is prone to disruption, Plasmodium.sp antigenes are present in higher concentrations and may be faster presented to the immune cells.
Sickle cell anaemia is where the red blood cells become sickle shaped hence since Plasmodium infests itself in the red blood cell for oxygen, it doesn't survive because sickle celled RBCs carry less volumes of oxygen.