T. Abe et al., INTESTINAL PROTECTION AGAINST STRONGYLOIDES-RATTI AND MASTOCYTOSIS INDUCED BY ADMINISTRATION OF INTERLEUKIN-3 IN MICE, Immunology, 80(1), 1993, pp. 116-121
Information about interleukin-3 (IL-3) effects in vivo is limited comp
ared with the in vitro effects. We found that a repetitive injection o
f a low dose of recombinant IL-3 induced protection against intestinal
worms of Strongyloides ratti in C57BL/6 mice. When mice were injected
i.p. with different doses of recombinant IL-3 twice a day from day -5
to day -1 and infected orally with larvae recovered from the head of
infected rats on day 0, worm recovery from the small intestine was mar
kedly reduced by a total of 10(4) U IL-3 or more on day 2 post-infecti
on. The number of intestinal mucosal mast cells (MMC) was increased by
the protective dose of IL-3. The IL-3 treatment, however, was ineffec
tive in protecting mice against tissue migrating larvae, as assessed b
y recovery from the head. The protective effect of IL-3 on intestinal
worms was observed within 6 hr post oral infection, suggesting little
concern with antigen-specific immune responses. The effective dose of
IL-3 treatment increased the number of MMC progenitors five times in t
he spleen and the mesenteric lymph nodes. An MMC-specific protease, MM
CP-1, was secreted 200 times more than in controls in the intestinal l
umen by the IL-3 treatment. The IL-3 treatment induced no protection o
r mastocytosis in mast cell-deficient W/W(v) mice. These results sugge
st that the IL-3-induced intestinal protection against S. ratti is med
iated by MMC.