Nt. Gross et al., INTERACTION BETWEEN CRYPTOCOCCUS-NEOFORMANS AND ALVEOLAR MACROPHAGES, Journal of medical and veterinary mycology, 35(4), 1997, pp. 263-269
Phagocytosis, oxidative metabolism and phagolysosomal pH of rat alveol
ar macro-phages (AM) were studied at different points of time after ch
allenge with Cryptococcus neoformans. Phagocytosis was evaluated using
a fluorescent quenching technique which distinguishes between attache
d and ingested organisms. The nitroblue tetrazolium (NET) test was use
d as an indirect measurement of the oxidative metabolism of the phagoc
ytes. The pH of the phagolysosomes was measured using a cytofluorometr
ic technique. Both the attachment and ingestion of serum opsonized C.
neoformans by AM were slow during the first hours of incubation, but w
ere considerable after 24 h. The oxidative metabolism of AM challenged
with the yeast was insignificant during the first hour, but reached h
igh levels after 24 h. Most phagolysosomes in AM with ingested cryptoc
occi had a pH < 5.5. Our results indicate that these AM defence mechan
isms, although poor during the first hours after exposure to the yeast
, are of significance after 24 h. Thus, in the immunocompetent host th
e AM should prevent the dissemination of C. neoformans from the lungs.