Altered lysophospholipase B responsiveness in lactating mice infected with intestinal nematode parasites.

Lactating and nulliparous outbred Swiss (CF-1 strain) mice were infected at 12-16 weeks of age with Nippostrongylus brasiliensis or Trichinella spiralis. Lysophospholipase B levels in the intestinal tissue and faecal pellets were greatly in infected lactating mice in contrast to infected nulliparous mice. Correlated with these depressions in lysophospholipase levels were markedly reduced numbers of bone-marrow eosinophils in infected lactating mice. Although the peak levels of lysophospholipase in the intestinal tissues occurred in both nulliparous and lactating mice by days 9 and 14 after infection with N. brasiliensis and T. spiralis, respectively, lactating mice had significantly lower lysophospholipase peak levels than nulliparous mice. The peak of luminal levels of the enzyme coincided with peak levels of the enzyme in the intestinal tissues and with the expulsion of the majority of the worms from the small intestines of nulliparous mice. However, lactation delayed the temporal relation between the peak of lysophospholipase levels in the intestinal lumen and worm expulsion. These results suggest that lactation depressed the levels of the enzyme and interfered with its release into the intestinal lumen.