蛍光染色によるマラリア原虫の研究 ： 迅速診断のための形態と核DNA量の変化に関して

Abstract

The relationship between the shape and nuclear DNA contents of malarial parasites of P. vivax (Pv) and P. falciparum (Pf) by microfluorometry on fluoro-stained thin blood films was studied in order to establish the usefulness of the method for simple and rapid diagnosis of malaria. In brief, thin blood films were prepared from 5 cases with Pv malaria and 3 cases with Pf malaria, fixed with methyl alcohol and stained with 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI). DNA contents were expressed in arbitrary fluorescence units (FU). When the average nuclear DNA contents of human mature granulocytes were 100.6 FU, those of ring form malarial parasites (R) were 1.1 FU and there was no significant difference of these value between Pf and Pv. As the FU of R was haploid (1C) value, DNA contents of trophozoites of Pv were increasing in proportion to development, but up to 2C. Referring to DNA contents, the observation of the shape of Pv parasites revealed that some of the so-called mature trophozoites had more times DNA contents than haploid value. Therefore, these parasites were newly named "immature schizonts". Schizonts with 2 nuclei showed 2C DNA contents, while the number of nuclei was directly proportional to the DNA contents in the schizonts with 3 nuclei or more. Macrogametocytes (MG) and microgametocytes (mG) of Pv and Pf had more DNA contents than those of R value and mG of Pv had 1-6 times as much DNA value as R, probably reflecting various stages of DNA synthesis up to octoploid (8C). Nearly all young gametocytes of Pv and Pf had the diploid (2C) value of DNA. Exflagellating microgametes of Pv showed the haploid value. The observation of periodically-sampled blood smears from a case with Pv malaria revealed that the number of gametocytes increased with decrease of counts of asexual forms, and decreased with increase of counts of asexual forms before and after the treatment. Additionally, DAPI staining revealed a decrease in DNA contents in the Pf parasites of crisis form in the patients with high IFA titer. Thus, for the better understanding of malarial parasites, critically needed is not only pure morphological information but also cytochemical data such as nuclear DNA contents in the parasites.