ABSTRACT
Paroxysmal nocturnal hemoglobinuria [PNH], a clonal hematopoietic stem cell disorder, manifests when the PNH clone populates in the hematopoietic compartment. We explored the roles of different apoptosis of GPI+ and GPI- [glycosylphosphatidylinositol] cells and CD8+ lymphocytes in a selection of PNH clones. Granulocytes from PNH patients and normal controls were subjected to an apoptosis assay using annexin V. Hematopoietic cell in semisolid media were cultured with or without CD8+ lymphocytes. In PNH, CD59+ granulocytes exhibited more apoptosis than their CD59- counterparts, after 0 or 4 hours in liquid growth culture system [mean [standard error of mean]: 2.1 [0.5] vs 1.2 [0.2], P=.01 at 0 hour and 3.4 [0.7] vs 1.8 [0.3], P=.03 at 4 hour, respectively]. The presence of mononuclear cells [MNCs] rendered a greater difference in apoptosis. The percentages of apoptotic CD59+ granulocytes measured at 4 hours with or without MNC fraction were correlated with the sizes of PNH clones [r=0.633, P=.011; and r=0.648, P=.009; respectively]. The autologous CD8+ lymphocytes inhibited CFU-GM and BFU-E colony formation in PNH patients when compared with normal controls [mean [SEM] of percentages of inhibition: 61.7 [10.4] vs 11.9 [2.0], P=.008 for CFU-GM and 26.1 [6.9] vs 4.9 [1.0], P=.037 for BFU-E]. Increased apoptosis of GPI+ blood cells is likely to be responsible in selection and expansion of PNH clones. MNCs or possibly CD8+ lymphocytes may play a role in this phenomenon
ABSTRACT
Background: Pythium insidiosum is an oomycete that infects both humans and animals, leading to a life-threatening infectious disease called “pythiosis”. Animal pythiosis presents with lesions of the skin, gastrointestinal tract, lung and bone, whereas human pythiosis presents with two common clinical forms, vascular pythiosis involving arteries, and ocular pythiosis involving the eye. Pythiosis in humans has been reported exclusively from Thailand. The disease in animals has been found around the world, but its occurrence has never been reported from Thailand.Objective: To group P. insidiosum based on molecular phylogenetic analysis, investigating correlation between phylogenetic group, geographic distribution, and host specificity of this pathogen.Methods: 113 rDNA internal transcribed spacer sequences of P. insidiosum were also obtained for phylogenetic analyses. These included 32 human isolates and 59 environmental isolates from Thailand, and four additional human isolates and 18 animal isolates from around the world.Results: P. insidiosum existed in three distinct clades in accordance with geographic distribution; clade-I contained American isolates, clade-II contained Asian and Australian isolates, and clade-III contained mainly Thai isolates. The Thai isolates existed only in clade-II and clade-III.Conclusion: There were two major subpopulations of P. insidiosum in Thailand. There were no correlation between the two Thai subpopulations of P. insidiosum and geographic regions or host specificity.