When non-permissive hosts are infected with Angiostrongylus cantonensis, the migration of the worms to the brain and their subsequent development manifests as marked eosinophilic pleocytosis. We used microchambers to demonstrate direct eosinophil chemotactic activity by adding a variety of antibodies into cerebrospinal fluid (CSF) of BALB/c mice 21 days post-infection with A. cantonensis. The antibodies were directed to neutralize eotaxin, RANTES (regulated on activation, normal T-cells expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and platelet-activating factor (PAF), respectively. Eosinophil migration into the polycarbonate membrane covering CSF with anti-eotaxin or anti-MIP-1alpha antibodies was significantly lower than that for antibody-free CSF (Student's t test: p < 0.01, p < 0.05). We also collected CSF from mice 21 days after infection with 10, 20, 30, 40, and 50 third-stage larvae (L3) respectively for dose-dependent testing, and 40 L3 at days 7, 14, and 21 after infection for time-dependent testing. Chemokine production in CSF was affected by A. cantonensis infection intensity and post-infection time. In conclusion, eotaxin and MIP-1alpha released in the CSF of A. cantonensis-infected mice have eosinophil chemotactic activity in this in vitro assay.
The kinetics of changes in the eotaxin concentration in the serum and cerebrospinal fluid (CSF) of BALB/c mice after infection with Angiostrongylus cantonensis and the correlation between the concentration of eotaxin and worm recovery were investigated. The mean concentration of eotaxin in serum of infected mice gradually increased from 46.3+/-6.5 pg/ml at week 0 to 104.9+/-44.8 pg/ml at week 3 after infection, while the mean eotaxin level in the CSF of infected mice rapidly increased from 18.7+/-2.1 pg/ml to 193.2+/-23.6 pg/ml 1 week after infection and then increased further to 507.8+/-167.9 pg/ml at week 3. The concentrations of eotaxin in the CSF of infected mice each week after infection were all significantly higher than those in serum ( P<0.0001). In parallel with the increase in eotaxin in the CSF, infected mice showed gradual increases in CSF eosinophilia and a reduction in intracranial worm recovery. The concentration of eotaxin in CSF was higher in infected mice with more worms in the brain, except when the number of worms in the brain was >30. In addition, when the worm counts in the brains of infected mice were <30, eotaxin concentrations in the CSF were positively correlated with worm counts in the brain ( P<0.001). Thus, the release of eotaxin in the CSF of mice infected with A. cantonensis observed in this study was time dependent and worm-load dependent, and in parallel with the increase in eotaxin in the CSF, and gradual decreases in worm counts in the brains of infected mice.
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