INACTIVATION OF TRYPANOSOMA-CRUZI TRYPOMASTIGOTE FORMS IN BLOOD COMPONENTS BY PHOTODYNAMIC TREATMENT WITH PHTHALOCYANINES

Three phthalocyanine dyes HOSiPcOSi(CH3)(2)(CH2)(3)N(CH3)(2) (Pc 4), H OSiPcOSi(CH3)(2)(CH2N+(CH3I- (Pc 5) and aluminum tetrasulfophthalocyan ine hydroxide (AlOHPcS(4)) were evaluated for their ability to inactiv ate the trypomastigote form of Trypanosoma cruzi in fresh frozen plasm a (FFP) and red blood cell concentrates (RBCC). The compound Pc 4 was found to be highly effective in killing T. cruzi, Pc 5 less effective and AlOHPcS(4) ineffective. With FFP as the medium, a complete loss of parasite infectivity in vitro (greater than or equal to 5 log(10)) wa s found to occur with 2 mu M Pc 4 after irradiation with red Light (>6 00 nm) at a fluence of 7.5 J/cm(2), while with RBCC as the medium, a c omplete loss was found to occur at a fluence of 15 J/cm(2). Even witho ut illumination, Pc 4 at 2 mu M also killed about 3.7-4.1 log(10) of T . cruzi in FFP during 30 min. Observed differences in T. cruzi killing by the various phthalocyanines may relate to differences in binding; Pc 4 binds to the parasites about twice as much as Pc 5. Ultrastructur al analysis of treated parasites suggests that mitochondria are a prim ary target of this photodynamic treatment. The data indicate that Pc 4 combined with exposure to red Light could be used to eliminate bloodb orne T. cruzi parasites from blood components intended for transfusion . The inactivation of T. cruzi by Pc 4 in the dark suggests a possible therapeutic application.