A multicomponent hemolytic system in the pathogenic amoeba Naegleria fowleri

A hemolytic activity associated with postnuclear supernatant fractions of Naegleria fowleri has been partially characterized in an attempt to isolate cytolytic molecules that may participate in naeglerial cytopathogenicity. Hemolysis by naeglerial postnuclear supernatant fractions was sensitive to heat and trypsin hydrolysis, and was inhibited by divalent cations. The majority of the hemolytic activity was nonlatent and associated with a particle fraction sedimenting at 48,000 X g (maximum) for 1 h. This particle-associated hemolytic activity appears to be membrane associated, as high salt concentration, chelating agents, and pH extremes were ineffective in solubilizing the hemolytic activity, whereas treatment with 0.15% Zwittergent 3-12, a dipolar ionic detergent, results in 98% release of the sedimentable hemolysin. The sigmoidal nature of the progress curve of postnuclear supernatant hemolysis, as well as synergistic interactions between fractions of amoebal whole cell extracts, suggests that the hemolytic activity has a multicomponent nature, with at least two and possibly three components participating in the hemolytic event. The significance of these findings in the context of naeglerial cytopathogenicity is discussed.