Introduction CD163 or soluble haemoglobin scavenger receptor is exclusively expressed in the monocyte-macrophage cell lineage. The expression of CD163 is down-regulated by lipopolysaccharide, and up-regulated by interleukin-6 (IL-6), dexamethasone and interleukin-10. sCD163 is suggested to be a product shed from the monocyte-macrophage membrane. Increased plasma levels of sCD163 have been observed in sepsis. The monocyte-macrophage cell lineage is important in the innate immune which makes sCD163 an interesting candidate marker in sepsis. This marker has not previously been evaluated in children with invasive pneumococcal disease (IPD).

Aims To evaluate the role of sCD163 in the immmunopathogenesis of IPD in Malawian children.

Methods Children with IPD had blood samples taken on admission for cytokine analysis, pneumococcal bacterial loads and full blood count.

Results A total of 158 children were recruited of which 88 (56%) were male, and 42 (27%) died. There were 93 (59%) HIV-infected children. sCD163 was significantly higher in HIV-infected children (p = 0.001), and in non-survivors (p = 0.008). sCD163 was higher in children with meningitis (n = 130) compared with those with pneumonia (n = 28), (p = 0.007). There was a weak correlation between sCD163 and IL-6 (r = 0.25, p = 0.003) but not with IL-10. There was no correlation with age or pneumococcal bacterial load. The Area under the Curve for cD163 for predicting mortality in IPD was 0.64 (95% CI 0.54 to 0.74).

Conclusions The macrophage marker CD163 appears to predict mortality in IPD in Malawian children.