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Pediatric Infectious Diseases Revisited - part 6

Cách đây vài năm, các nhà nghiên cứu đã bắt đầu nhấn mạnh sự đóng góp của dyserythropoiesis tủy xương để tình trạng thiếu máu của bệnh sốt rét falciparum [81, 82]. Một nhóm ở Oxford [83], tìm kiếm một lời giải thích cho dyserythropoiesis này thông qua một nghiên cứu kính hiển vi | 248 Ian A. Clark and Michael J. Griffiths retard replacement. Some years ago researchers began to stress the contribution of bone marrow dyserythropoiesis to the anaemia of falciparum malaria 81 82 . A group in Oxford 83 seeking an explanation for this dyserythropoiesis through an electron microscopy study of bone marrow observed sequestration of parasitised red cells and argued that this caused the bone marrow dysfunction in falciparum malaria by restricting blood flow and thus inducing hypoxic changes. This idea proved inadequate however when this same group subsequently reported dyserythropoiesis and erythrophagocytosis in vivax malaria in which parasitised red cells do not sequester 84 . Some time ago an undefined product in macrophage supernatants 85 later identified as TNF 86 was found to inhibit the growth and differentiation of erythroid progenitor cells. When rTNF became available the dyserythropoiesis and erythrophagocytosis seen in terminal Plasmodium vinckei-infected mice was reproduced by giving a single injection early in the course of the infection 87 . Phagocytosis of erythroblasts in bone marrow a phenomenon also reported by Wickramasinghe et al 83 84 in human malaria also occurred. Decreased erythropoiesis was subsequently reported in mice receiving continuous TNF infusions via implanted osmotic pumps and mice expressing high levels of human TNF have been shown to become markedly anaemic during malaria infections 68 even though parasite numbers and therefore red cell loss post-schizogony are considerably reduced. The past decade has seen an expansion of this line of enquiry into human malaria and also the number of cytokines both pro-inflammatory and anti-inflammatory 88 89 in absolute amounts and ratios 90 91 that have been investigated in this context. Investigations have been extended to include other pro-inflammatory cytokines such as IL-12 92 and FasL 93 and examined the role in anaemia of the persistence of cytokine production during malaria