Correlation of APRIL with production of inflammatory cytokines during acute malaria in the Brazilian Amazon.

INTRODUCTION

A proliferation-inducing ligand (APRIL) and B cell activation factor (BAFF) are known to play a significant role in the pathogenesis of several diseases, including BAFF in malaria. The aim of this study was to investigate whether APRIL and BAFF plasma concentrations could be part of inflammatory responses associated with P. vivax and P. falciparum malaria in patients from the Brazilian Amazon.

METHODS

Blood samples were obtained from P. vivax and P. falciparum malaria patients (n = 52) resident in Porto Velho before and 15 days after the beginning of treatment and from uninfected individuals (n = 12). We investigated APRIL and BAFF circulating levels and their association with parasitaemia, WBC counts, and cytokine/chemokine plasma levels. The expression levels of transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) on PBMC from a subset of 5 P. vivax-infected patients were analyzed by flow cytometry.

RESULTS

APRIL plasma levels were transiently increased during acute P. vivax and P. falciparum infections whereas BAFF levels were only increased during acute P. falciparum malaria. Although P. vivax and P. falciparum malaria patients have similar cytokine profiles during infection, in P. vivax acute phase malaria, APRIL but not BAFF levels correlated positively with IL-1, IL-2, IL-4, IL-6, and IL-13 levels. We did not find any association between P. vivax parasitaemia and APRIL levels, while an inverse correlation was found between P. falciparum parasitaemia and APRIL levels. The percentage of TACI positive CD4+ and CD8+ T cells were increased in the acute phase P. vivax malaria.

CONCLUSION

These findings suggest that the APRIL and BAFF inductions reflect different host strategies for controlling infection with each malaria species.