Cerebral malaria (CM) accounts for nearly 400,000 deaths annually in African children. Current dogma suggests that CM results from infected RBC (iRBC) sequestration in the brain microvasculature and resulting sequelae. Therapies targeting these events have been unsuccessful; findings in experimental models suggest that CD8⁺ T cells drive disease pathogenesis. However, these data have largely been ignored because corroborating evidence in humans is lacking. This work fills a critical gap in our understanding of CM pathogenesis that is impeding development of therapeutics.

Using multiplex immunohistochemistry, we characterized cerebrovascular immune cells in brain sections from 34 children who died from CM or other causes. Children were grouped by clinical diagnosis (CM⁺ or CM^–), iRBC sequestration (Seq^hi, Seq^lo, Seq⁰) and HIV status (HIV⁺ or HIV^–).

We identified effector CD3⁺CD8⁺ T cells engaged on the cerebrovasculature in 69% of CM⁺ HIV^– children. The number of intravascular CD3⁺CD8⁺ T cells was influenced by CM status (CM⁺ > CM^–, P = 0.004) and sequestration level (Seq^hi > Seq^lo, P = 0.010). HIV coinfection significantly increased T cell numbers (P = 0.017) and shifted cells from an intravascular (P = 0.004) to perivascular (P < 0.0001) distribution.

Within the studied cohort, CM is associated with cerebrovascular engagement of CD3⁺CD8⁺ T cells, which is exacerbated by HIV coinfection. Thus, CD3⁺CD8⁺ T cells are highly promising targets for CM adjunctive therapy, opening new avenues for the treatment of this deadly disease.

This research was supported by the Intramural Research Program of the National Institutes of Health.