Primary proliferative polycythaemia without splenomegaly: a diagnostic problem.

We report three cases of polycythaemia with no evidence of clinical splenomegaly and normal splenic red cell pool on isotope spleen scan. In each case, however, a diagnosis of primary proliferative polycythaemia (PPP) was suggested by in-vitro erythropoietin-independent growth of peripheral blood erythroid colonies. In one of these cases two possible causes of secondary polycythaemia were also identified. The use of investigations such as isotope spleen scanning and erythroid cell culture in helping to establish a diagnosis of PPP is discussed.

Fine analysis of the active H5 gene chromatin of chicken erythroid cells at different stages of differentiation.

We have analyzed the chromatin structure of a region that encompasses 14.4 X 10(3) base-pairs of the chicken histone H5 locus in adult erythroid cells at different stages of maturation. Seven of eight major lineage-specific DNase I-hypersensitive sites, some of which show complex substructure, were found in the flanking regions of the gene. The hypersensitivity of some of these sites is modulated during erythrocyte maturation in a way that parallels the transcriptional activity of the gene. DNase I, micrococcal nuclease, and S1 nuclease recognize the same regions, which differ from those cleaved by S1 on supercoiled plasmid DNA. This suggests that hypersensitivity of DNA in chromatin reflects a greater accessibility of the DNA rather than its altered conformation. The DNA sequence of some of the DNase I target sites contains repeated motifs, (T-C-C-C)2, (T-C-C)2, (T-G-G-G-G)2, which are found in the hypersensitive sites of other genes. Detailed analysis across sections of the H5 gene and flanking sequences revealed differences in the DNase I sensitivity of the different regions examined. Notably, the first one-third of the gene is more sensitive than the rest. The sequences downstream from the region where most RNA polymerases terminate transcription were found to be the most resistant.

Characterization of erythroid and granulocyte monocyte progenitors in human cord blood.

Some characteristics of both erythroid and granulocyte monocyte progenitors in human cord blood were compared to those in adult blood and bone marrow. The number of progenitors in cord blood was higher than that in adult blood and bone marrow. Most colonies in cord blood culture were monocyte-macrophage, whereas those from adult blood were largely eosinophilic. Cord blood progenitors had a slower sedimentation velocity than that reported for marrow, but sedimented faster than that for adult blood. A significant proportion of progenitors in cord blood as well as adult marrow was found to be in the DNA synthetic phase of the cell cycle whereas progenitors in adult blood were not. Cord blood BFU-E were more resistant than adult blood BFU-E but cord blood CFU-GM were not different from adult blood CFU-GM with regard to radiation sensitivity. Cord blood CFU-GM appeared to be more radio-resistant than adult marrow GFU-GM. From these results is seems clear that progenitors in cord blood differ in some aspects from those in adult blood and bone marrow.

Partial characterization of bone marrow hemopoiesis in mice after cisplatin administration.

After cessation of cisplatin (cis-dichlorodiammineplatinum) chemotherapy, selective recovery of certain cell lineages occurs during bone marrow hemopoiesis. To further investigate the process of selective hemopoiesis, we combined the use of buoyant density gradient separation, morphology, and lymphocyte function assays to characterize changes in the hemopoiesis of immature and mature marrow cells after exposure to cisplatin. A single, cytotoxic dose of cisplatin was administered to B6D2F1 male mice, and marrow cell suspensions were taken from these mice 3 and 7 days later to characterize hemopoietic recovery. Morphology and buoyant density separation of marrow cells revealed that the most significant changes in cellular composition occurred at Day 3. At this time, there was an increase in immature white blood cells (WBCs) and immature polymorphoneutrophils (PMNs) with a concomitant reduction in immature red blood cells (RBCs). By Day 7, the normal proportion of immature RBCs, immature WBCs, and PMNs was restored; however, the buoyant distribution patterns for PMNs indicated that a greater proportion of immature PMNs was still present relative to marrow suspensions from normal mice. Fewer lymphocytes were also observed in marrows from the Day 7 group when compared with controls. Lymphocyte function tests indicated reduced mitogen responsiveness of lymphocytes from both Day 3 and Day 7; however, more immature lymphocytes were present after 7 days than were seen with either normal or Day 3 marrow suspensions. Overall, the results indicated that hemopoiesis proceeded through a specific hierarchy which began with the restoration of the erythrocyte line followed by the leukocyte cell lines. Lymphocyte recovery lagged behind the restoration of all the cell lineages examined.

Chicken fetal antigen expression on the definitive erythroid maturation series in the bone marrow of the adult chicken.

Chicken fetal antigen (CFA) describes a membrane developmental antigen system present on embryonic and fetal erythroid cells that is present during development, but is absent on erythrocytes of mature chickens. In this study, CFA was detected by indirect immunofluorescence and correlated with six stages of morphological maturation of erythroid cells. All cells in the erythroid series through the late polychromatic erythrocyte (reticulocyte) stage were found to possess CFA. Fluorescent intensity and staining patterns of the definitive erythroid series demonstrated CFA concentration increase and distribution pattern change throughout erythroid maturation.

Hemoglobin alpha chain deficiency in black children with variable quantities of hemoglobin Bart's at birth.

Hematologic and globin chain synthesis studies have been made in 21 children, aged 2 to 6 years, many of their parents, and several normal adults and alpha-thalassemia heterozygotes. At birth, 11 children had about 5% hemoglobin (Hb) Bart's, 5 had about 2% Hb Bart's, and 5 had no trace of Hb Bart's. A significant decrease in mean corpuscular volume. (MCV) and mean corpuscular hemoglobin (MCH) values and an increase in the beta/alpha ratio was observed in the first group; microcytosis and hypochromia were absent in the children of the second group although the beta/alpha ratio was significantly increased. The alpha chain deficiency is familial. Increased alpha/alpha ratios were present in many parents although only two parents of children with 5% Hb Bart's at birth had hematologic findings suggestive of the presence of the same type of defect as observed in the children with the larger amount of Hb Bart's at birth.