Stimulatory factors for interleukin 12 (IL-12) production associated with
Babesia microti and
Babesia
rodhaini infected erythrocytes were examined using an
in vitro assay system established, since a
remarkable increase of serum IL-12 concentration and differentiation of helper T cell (Th cell) into helper
T cell type 1 (Th1 cell) was observed in early phase of infection with
Babesia spp. in mice. To investigate
direct stimulating activity of infected erythrocytes for IL-12 production, intact splenic macrophages were
co-cultured with them and examined the expression of IL-12 mRNA by reverse transcription-polymerase
chain reaction (RT-PCR). Both
B. microti and
B. rodhaini infected erythrocytes elicited IL-12 mRNA
expression in co-cultured macrophages. Since only the supernatant obtained from the cultured medium of
infected erythrocytes showed an activity for IL-12 production from macrophages, the supernatant was
collected, concentrated, and heated, followed by the collection of soluble fraction. As the heat stable
soluble supernatant showed an IL-12 production activity, it was fractionated by gel filtration. The elution
profile of the heat stable soluble supernatant from
B. microti infected erythrocytes was quite different to
that from
B. rodhaini infected and non-infected erythrocytes. The differences of stimulatory activity were
also observed in the fraction of eluate, especially Fraction 3, between
B. microti infected erythrocytes,
and
B. rodhaini infected and non-infected erythrocytes. These results suggested that
B. microti infected erythrocytes and/or
B. microti itself released some factors to stimulate IL-12 production from splenic macrophages, resulted in the Th1 differentiation.
抄録全体を表示