Isolation and characterisation of an anticryptococcal protein in human cerebrospinal fluid

Abstract

An earlier study reported that human cerebrospinal¯uid (CSF) has fungistatic activity for Cryptococcus neoformans. The present study reports that molecular sieve fractionation of concentrated CSF yielded three protein peaks, one of which (p2) had anticryptococcal activity. On a DEAE-Sephacel anion-exchange column the active molecular sieve peak (p2) gave two peaks that contained anticryptococcal activity. The ®rst (DEAE-1) eluted with 0.1 M NaCl and the second (DEAE-2) eluted with 0.2 M NaCl in buffer. Fungistatic activity of DEAE-1 was reversed by FeCl 3 . Moreover, FeCl 3 reversed inhibition of C. neoformans growth by CSF. In contrast, activity of DEAE-2 was not reversed by FeCl 3 , indicating that inhibition was produced by an ironindependent mechanism. Immunoblot assays showed that transferrin was present in DEAE-1 but not in DEAE-2, whereas albumin was present in DEAE-2 but not in DEAE-1. On NuPAGE, DEAE-1 protein migrated as a single band corresponding to transferrin and DEAE-2 protein gave a single band corresponding to albumin. In control experiments, human serum albumin subjected to the same isolation protocol acquired anticryptococcal activity similar to that of DEAE-2. Therefore, CSF albumin (DEAE-2) activity was associated with the isolation protocol. These data indicate that transferrin, present in or isolated from CSF, sequesters trace amounts of ferric iron, inhibits growth of C. neoformans and acts as an innate defence mechanism.

A Microtus fortisprotein, serum albumin, is a novel inhibitor of Schistosoma japonicumschistosomula

“…It is well known that serum albumin is the most abundant protein in the circulatory system and it possesses many important physiological functions that contribute to colloid osmotic blood pressure and aid in the transport, distribution and metabolism of many endogenous and exogenous substances. In addition, it was reported that albumin might play an important role in innate immunity ( Fassi et al 1993 , Brummer et al 1999 , Ahluwalia et al 2001 ). Giles and Czuprynski (2003) showed that the albumin from several mammalian species had obvious inhibitory activity against Blastomyces dermatitidis , while analbuminaemic rat serum failed to inhibit B. dermatitidis growth in vivo.…”

Cryptococcus neoformans Gene Expression during Experimental Cryptococcal Meningitis

“…The increased abundance of a tag corresponding to the phosphate transporter in vivo correlates well with our identification of an increased abundance of tags for genes encoding the electron transport chain. Iron in the CSF is bound to brain-derived transferrin, and the availability of iron for C. neoformans is thought to be limited during infection (1). This finding correlated with the significant increase in the abundance of a tag corresponding to an iron permease gene observed under in vivo conditions relative to in vitro conditions.…”

Shared and distinct mechanisms of iron acquisition by bacterial and fungal pathogens of humans

“…Transferrin and lactoferrin are known to have an inhibitory effect on the growth of the pathogenic fungi A. fumigatus , C. albicans and C. neoformans (Sridhar et al, 2000 ; Ahluwalia et al, 2001 ; Lahoz et al, 2008 ; Almeida et al, 2009 ; Kornitzer, 2009 ; Okazaki et al, 2009 ). The mechanism of inhibition is probably due to iron sequestration by partially iron-loaded protein because additional studies have shown that these fungi can acquire iron from fully iron-loaded transferrin under specific conditions.…”