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/

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    $\begingroup$ Possible duplicate of Why do heterozygous individuals have increased resistance to malaria? $\endgroup$ – De Novo supports GoFundMonica Aug 1 '18 at 19:52
  • $\begingroup$ @DeNovo I was having a hard time understanding it; another approach to answer the question would be appreciated. $\endgroup$ – user73023 Aug 1 '18 at 20:24
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    $\begingroup$ In someone with sickle cell trait (a heterozygote), red cells are typically normal. When those red cells are infected with P. falciparum, though, they sickle and are easy for phagocytes to capture and kill. This makes it hard for the parasite to reproduce and cause significant disease. $\endgroup$ – De Novo supports GoFundMonica Aug 1 '18 at 20:35
  • $\begingroup$ I would not consider it a duplicate the linked question does not address the mechanism of resistance. $\endgroup$ – John Aug 8 '18 at 15:33
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    $\begingroup$ @DeNovo No it doesn't, it completely glosses over what it is about sickle cells that actually makes them detrimental to plasmodium infection. "the chances are bigger they will be phagocytized" is the sum total of the explanation, without even a mention of why the chances are higher. $\endgroup$ – John Sep 6 '18 at 11:13

I would say that there are at least 2 explanations:

  1. 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.
  2. 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.

  • $\begingroup$ do you have a source for this? $\endgroup$ – John Oct 6 '18 at 13:19

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