Emperipolesis of marrow cells within megakaryocytes in the bone marrow of sublethally irradiated mice
- 78 Downloads
The incidence of megakaryocytic emperipolesis was studied in the bone marrow of normal and X-irradiated mice. Two groups of mice received total body irradiation with a single dose of 5 Gy and one of the two groups had been treated with a radioprotective drug, ethiofos (WR-2721), before irradiation. Mice from a third group remained unexposed to irradiation and served as controls. The Wright-Giemsa stained bone marrow smears were analyzed every 5 days during a 30-day period, starting 1 day after irradiation. The number of megakaryocytes exhibiting the phenomenon was determined and expressed as an average value for every experimental group. The frequency of megakaryocytic emperipolesis was less than 15% of megakaryocytes from control smears but increased to 34% in mice that had only been irradiated and to 43% when mice were treated with WR-2721 before irradiation. In the last case, i.e., irradiation and treatment with a radioprotective drug, a positive correlation between the macrocytic megakaryocytes and elevated emperipolesis was noted. Under light microscopy, there were no signs of phagocytosis; engulfed cells remained unaltered with their normal structure intact. Granulocytic, erythroid, and lymphoid cells appeared to be the most frequent marrow cells engulfed by mature megakaryocytes. The number of incorporated cells in one megakaryocyte ranged from 1 to 3, though occasionally more than 6 were seen in macrocytic megakaryocytes. Based on our findings and on a review of the associated literature, we believe emperipolesis is an interesting cellular phenomenon related to the fast passage of marrow cells across the marrow-blood barrier, especially through the cytoplasm of megakaryocytes in response to an increased demand for cell delivery. The high demand for cell delivery which occurs after irradiation may cause certain mature bone marrow cells to take a transmegakaryocyte path to enter the circulation of the blood. Irradiation seems to have an immediate effect (observed after 24 h) on emperipolesis, suggesting that a humoral factor is involved in the pathogenesis.
Key wordsEmperipolesis Megakaryocytes Sublethal irradiation WR-2721 (ethiofos) Bone marrow
Unable to display preview. Download preview PDF.
- 2.Bobik R (1993) Influence of X-irradiation and radioprotective drug on the megakaryocyte-platelet system of mice (in Polish). Doctoral dissertation, The Jagiellonian University, CracowGoogle Scholar
- 3.Beutler E (1984) Red cell metabolism. A manual of biochemical methods, 3rd edn. Grune and Stratton, New YorkGoogle Scholar
- 4.Breton-Gorius J (1981) On the alleged phagocytosis by megakaryocytes. Br J Haematol 47:653Google Scholar
- 5.Burkhardt R, Kleinknecht R, Jager R, Frish B, Mahl G, Bartl R (1984) Megakaryocytic emperipolesis — accidental or diagnostic sign? In: Lennert K, Hubner K (eds) Pathology of the bone marrow. G. Fischer, Stuttgart, pp 200–205Google Scholar
- 8.Chiu T (1983) Megakaryocytes with intracytoplasmic blood cells. Am J Vet Res 45:769–770Google Scholar
- 13.Migita M, Fukunaga Y, Watanabe A, Maruyama K, Ohta K, Kaneko K, Kaneda M, Kakinuma K, Yamatoto M (1992) Emperipolesis of neutrophils by megakaryocytes and thrombocytopenia observed in a case of Kostmann's syndrome during intravenous administration of high-dose rhg-CSF. Br J Haematol 80:413–415PubMedGoogle Scholar
- 19.Shamoto M (1981) Emperipolesis of hematopoietic cells in myelocytic leukemia. Virchows Arch [B] 35:283–290Google Scholar
- 21.Sobolewski S (1980) Phagocytosis by megakaryocytes in malignant disorders (abstract). Br J Haematol 45:173Google Scholar
- 25.Thiele J, Krech R, Choritz H, Georgii A (1984) Emperipolesis — a peculiar feature of megakaryocytes as evaluated in chronic myeloproliferative disease by morphometry and ultrastructure. Virchows Arch [B] 46:253–263Google Scholar
- 26.Thiele J, Schneidwer G, Hoeppner B, Wienhold S, Zankovich R, Fischer R (1988) Histomorphometry of bone marrow biopsies in chronic myeloproliferative disorders with associated thrombocytosis — features of significance for the diagnosis of primary (essential) thrombocythemia. Virchows Arch [A] 413:407–417Google Scholar