Rifampicin treatment of cutaneous leishmaniasis

In a small-scale preliminary trial of oral rifampicin treatment was considered successful in six out of eight cutaneous leishmaniasis patients and probably effective in a seventh. The in vitro effect of rifampicin on leishmania organisms concerns inhibition of mitochondrial function or replication. The need for protozoological control in the assessment of treatment is stressed.

Polyamines and the growth of leishmanial parasites

The relation between the grown of leishmanial parasites and polyamine biosynthesis was studied. Polyamines, mainly putrescine and spermidine, accumulated in macrophages infected with Leishmania tropica major promastigotes grown in vitro. Similar results were obtained, when tissues of BALB/C mice infected with L. tropica major were examined. A consistent increase in cellular putrescine and spermidine levels was observed in infected skin and spleen. With the accumulation of putrescine, a concomitant increase in ornithine decarboxylase activity was detected in growing leishmanial promastigotes and in macrophages supporting the growth of leishmanial amastigotes. An increase in the activity of ornithine decarboxylase was also observed in Leishmania-infected skin and spleen from BALB/C mice.

Antiparasitic structure-activity relationships of congocidine derivatives

Several congocidine analogs were synthesized and tested for in vivo activity against Trypanosoma congolense and in vitro activity against amastigotes of Leishmania tropica. The tripyrrole derivative, beta-([N-methyl-4-[N-methyl-4-(guanidinoacetamido)pyrrole-2-carboxamido]pyrrole -2-carboxamido]pyrrole-2-carboxamido)butyroamidine dihydrochloride, was less toxic and more active than congocidine. The guanidinoacetyl moiety appears to be a structural requirement for antiparasitic activity in the congocidine series.

Coagglutination and indirect hemagglutination in the detection of an excreted immunologically active substance from Leishmania

The methods of coagglutination and indirect hemagglutination were used to detect the production of the immunologically active excreted factor (EF) of Leishmania. Staphylococci, rich in protein A and sensitized with specific anti-Leishmania antibodies, coagglutinated with supernatant fractions of cultures, thus enabling continuous monitoring of the excretion of EF by multiplying parasites. Papain-treated human red blood cells, sensitized with crude or purified EF, also agglutinated with the coagglutination reagent. The sensitized papain-treated red blood cells may be employed in indirect hemagglutination to detect specific antibodies to Leishmania in rabbit and human sera. As the EF is specific for each Leishmania serotype group, coagglutination and indirect hemagglutination offer the possibility of rapid, easy, sensitive and specific diagnostic tools in the determinations of both antigen and antibody in specimens from suspected cases of leishmaniasis.

Leishmanial excreted factor: protein-bound and free forms from promastigote cultures of Leishmania tropica and Leishmania donovani

Leishmania spp. growing in culture produce an immunologically active substance called excreted factor (EF), which precipitates antibodies raised against intact cells and has been implicated as the conditioning agent for parasite infection of host macrophages. An improved method for isolation of the material is described, based on Sephadex column chromatography of growth medium which had been boiled at pH 5.0. This procedure allows the detection of differences among the EF molecules of different species, and it overcomes previous shortcomings through the monitoring of immunological activity throughout. Analysis of the products of this procedure revealed that EFs from Leishmania tropica and Leishmania donovani share a common carrier protein, identified as rabbit serum albumin, and are chemically quite similar. Growth medium from L. tropica boiled at acidic pH contains primarily an EF-albumin complex of 75,000 molecular weight. Treated growth medium from L. donovani, on the other hand, contains both the albumin complex and a smaller molecule (less than 27,000 molecular weight) that is not associated with rabbit protein. This material accounts for nearly 20% of the EF of one L. donovani strain, but constitutes only a minute fraction of L. tropica EF. Treatment of the EF-albumin complex with trichloroacetic acid separates the molecule into two major subunits, one having a molecular weight of about 61,000 (without anti-Leishmania activity) and the other having a molecular weight of about 18,000 (with no anti-rabbit activity). The protein-free EF of L. tropica differs from that released by trichloroacetic acid extraction in that it is capable of precipitating antisera of nonhomologous serotypes, whereas the albumin complex and the trichloroacetic acid-treated EF fragment are not. EFs from both species display pH-dependent affinity for certain lectins.