Malaria infection enhances IL-27 expression through IFN-γ production to promote the expansion, differentiation, and mobilization of LSK cells.

(A-B) Indispensable role for IFN-γ in the expansion of LSK cells after malaria infection. WT and IFN-γ-deficient mice were infected with the blood stage of P. berghei XAT. Seven days later, parasitemia was determined (A) and LSK populations were analyzed by flow cytometry (B). (C-D) IFN-γ-dependent induction of IL-27 p28 subunit expression by malaria infection. RNA was prepared 7 days after the infection and analyzed for expression of p28 by real-time RT-PCR (C), and serum p28 levels were determined by ELISA (D). (E-G) Decreased parasitemia and augmented expansion of LSK cell population in IFN-γ-deficient mice by IL-27. IFN-γ-deficient mice were hydrodynamically injected with IL-27-expression vector or control vector at days 0 and 4 after infection; at day 7, parasitemia was measured (E), LSK population was analyzed by flow cytometry (F), and cell numbers of LSK cells and neutrophils were counted (G). Data are shown as mean ± SEM (n = 3–5) and are representative of at least two independent experiments. *P < 0.05, **P < 0.01, ***P < 0.005.