The present study shows that treatment with recombinant human tumour
necrosis factor-α (rhTNF-α) can suppress
parasitaemia and prevents development of experimental cerebral malaria
(ECM) in Plasmodium berghei K173-infected
mice. Mice received rhTNF-α treatment either by subcutaneous injection
of free or liposome-encapsulated rhTNF-α or
sustained intraperitoneal administration of rhTNF-α given via mini-osmotic
pumps. Low-dose treatment with a subcutaneous bolus injection of rhTNF-α
protected against ECM when treatment was started on day 5 or 6 after infection.
The same protective efficacy was obtained either by subcutaneous injection
of liposome-encapsulated rhTNF-α or by
sustained release from osmotic pumps, but in the latter case a 10-fold
lower daily dose of rhTNF-α was sufficient.
Treatment with rhTNF-α substantially suppressed parasitaemia in ECM-protected
mice, but not in mice developing
ECM. Thus, the rhTNF-α mediated suppression of parasitaemia is directly
or indirectly involved in protection against
ECM. Sustained delivery of rhTNF-α through osmotic pumps, but not
by subcutaneous injection of liposome-encapsulated rhTNF-α, resulted
in increased concentrations of soluble mouse TNF receptor R75 (sTNFR75)
in plasma
at day 9 after infection when non-treated mice die of ECM. Thus, protection
against ECM is not directly correlated with
the sTNFR75 concentrations at day 9 after infection.