SENSITIVITY OF ENTAMOEBA-HISTOLYTICA AND ENTAMOEBA DISPAR PATIENT ISOLATES TO HUMAN-COMPLEMENT

Twenty-one Entamoeba histolytica and 56 Entamoeba dispar patient isola tes were investigated for their sensitivity to the classical and alter native pathway of human complement. E. histolytica and E. dispar patie nt isolates were differentiated by polymerase chain reaction and hexok inase isoenzyme typing. It was found that 90.3% (+/-12.0%) of the trop hozoites of E. histolytica were lysed after 30 min by the alternative pathway of complement in the presence of 50% human serum (19 isolates showed lysis rates higher than 80%), whereas E. dispar cells were less susceptible to the alternative pathway as 68.8% (+/-28.2%) of lysis o ccurred However, 23 of the E. dispar isolates were lysed between 100 a nd 80% (90.9%+/-9.1%), demonstrating that about half of the tested E. dispar isolates were highly sensitive to complement lysis. Only 11 of the E. dispar isolates were proven to be 'resistant' to the alternativ e pathway of complement and were lysed less than 40%. These results ar e in conflict to earlier publications, describing resistance of E. dis par to complement lysis (Hamelmann et al. 1992, 1993).