Association between parasite density and cytokines in malaria infected human placentas

Background: Placental malaria is a major cause of infection induced adverse conditions in pregnancy and is attributed to the sequestration of malaria parasite in the intervillous space. We investigated if any relationship exists between the parasite density and cytokines in malaria parasite infected human placentas. Methods: Sixty (60) malaria parasite infected placentas from apparently healthy immediate post-partum women and 40 malaria parasite uninfected placentas which served as control were studied. Blood from the human placenta was aseptically collected and tested for HIV and malaria parasite using standard methods. Interferon-Gamma (IFNγ), Tumor Necrosis Factor alpha (TNFα), Interleukin-4 (IL-4), Interleukin-6 (IL-6) and Interleukin-10 (IL-10) were measured by Enzyme-Linked Immunosorbent Assay (ELISA) technique. Data were analysed using appropriate statistical tools. Results: The result revealed P. falciparum with a mean parasite density of 762.47±459.62 parasite/µl of blood. The mean±SD (11.71±6.55pg/ml) and 55.57±43.13 pg/ml for IFNγ and IL-10 respectively for infected placenta was statistically higher on comparison with 5.58±2.86 pg/ml and 16.60±4.88 pg/ml for IFNγ and IL10 respectively for uninfected human placenta (P<0.05). Positive correlation existed between parasite density and IL-6 (r = 0.59, p = 0.001) and between parasite density and IL-10 (r =0.41, p=0.024). Conclusion: The study showed upregulated levels of IL-6 and IL-10 which indicates disruption of normal immune balance in the parasite infected placenta and the amount of IL-6 and IL-10 secreted could reflect the level of parasitaemia and could serve for diagnostic assessment of placental malaria.