Ultrastructural Studies of Peripheral Blood of Neonates with Down’s Syndrome and Transient Abnormal Myelopoiesis

Abstract

Ultrastructural studies were performed on blood samples from five neonates with Down's syndrome and transient abnormal myelopoiesis (TAM). Three methods of fixation were employed to detect diaminobenzidine (DAB) reactivity. The first method used glutaraldehyde solution, while the second and third methods used tannic acid-glutaraldehyde mixtures. Before fixation by the second method, specimens were washed in order to eliminate plasma, and before fixation by the third were diluted to lessen the effects of plasma protein. The latter two methods were more sensitive than the first for detection of DAB reactivity, while the third also resulted in better preservation of morphology than did the second. Even the first method was able to detect DAB reactivity in cells of megakaryocyte-platelet series in appropriate sections. Although the majority of blasts appeared with light microscopy to be undifferentiated, their ultrastructural morphology and ultrastructural cytochemistry were in fact found to be quite heterogeneous, consisting of cells of the megakaryocyte-platelet and granulocytic series, including basophils, and erythroid precursors. This finding supported the view that TAM was the result of unstable hematopoiesis rather than true leukemia.

Perinatal Visceral Fibrosis Accompanying the Megakaryoblastic Leukemoid Reaction of Down Syndrome

“…The use of surface and ultrastructural markers has shown that the transiently proliferating cells include a major megakaryocytic or megakaryoblastic component (3, [7][8][9][10], and this finding has been linked with previous knowledge that cases of acute leukemia presenting in older infants and children with Down syndrome include a disproportionately large number with megakaryoblastic leukemia (11)(12)(13). Zipursky et al (2) conclude that the available evidence suggests that the transient form of leukemia occurring in newborn infants with Down syndrome is acute megakaryoblastic leukemia in which there is a high rate of spontaneous regression.…”

Characterization of fetal haematopoietic progenitors circulating in maternal blood of seven aneuploid pregnancies

“…The circulating blasts in these patients were found to be quite heterogeneous in ultrastructural morphology and cytochemistry (Bessho et al, 1988), consisting of cells of megakaryocyte, granulocyte, and erythroid series.…”

Transient myeloproliferative disorder associated with trisomy 21, a wide range syndrome: Report of two cases with trisomy 21 mosaicism

“…Transient myeloproliferative disorder associated with trisomy 21 receives several other names throughout the literature reviewed: transient abnormal myelopoiesis [2,18], leukemoid reaction [&8, 101, transient leukemia [3] , and transient leukemoid proliferation [9].…”