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Hemodialysate or its three peptide fractions added to the culture of human bone stromal cells in vitro in concentration equal to 5 micrograms/ml of medium calculated against the protein content showed varying toxicity extent as expressed by shortening of cell survival time. Fraction III and hemodialysate showed the most toxic effect and shortened the cell survival time by three 24-hour periods in comparison to the control culture. Fraction III contained peptides having molecular weights in the range 1 to 5 kda that is was rich in compounds of the so-called middle molecular weights. Both hemodialysate and peptide fractions altered in the culture the participation of stromal cells reflected by diminishing the number of fibroblasts or adipocytes and an increase in the macrophage count. Above alterations speak in favor of concept that both hemodialysate and peptide fractions contain the macrophage proliferation stimulatory factor(s).

Morphologically distinct lymphoid cells with homogeneous, condensed chromatin and scant cytoplasm can be observed in large numbers in the bone marrow of children with a variety of hematologic and nonhematologic disorders. In some patients, these cells may account for greater than 50% of the bone marrow cells, creating a picture that can be confused with acute lymphoblastic leukemia (ALL) or metastatic tumor. Although originally called hematogones (HGs), a variety of other names have been proposed for these unique cells. The clinical significance of expanded HGs has not been resolved, and the biologic features of these cells are incompletely described. In this study, we correlate the clinical, morphologic, cytochemical, flow cytometric, molecular, and cytogenetic properties of bone marrow samples from 12 children with substantial numbers of HGs (range 8% to 55% of bone marrow cells). Diagnoses in these patients included anemia, four; neutropenia, one; anemia and neutropenia, one; idiopathic thrombocytopenic purpura, two; retinoblastoma, two; Ewing's sarcoma, one; and germ cell tumor, one. Flow cytometric analyses of bone marrow cells demonstrated a spectrum extending from early B-cell precursors (CD10+, CD19+, TdT+, HLA-Dr+) to mature surface immunoglobulin-bearing B cells in these patients, corroborating our morphologic impression of HGs, intermediate forms, and mature lymphocytes. DNA content was normal, and no clonal abnormality was identified by either cytogenetic or immunoglobulin and T-cell receptor (TCR) gene rearrangement studies. Follow-up ranged from 3 months to 3 years. None of the patients has developed acute leukemia or bone marrow involvement by solid tumor. The possible role of HGs in immune recovery and hematopoiesis is presented.

89Sr was used to ablate the marrows of 12- to 16-week-old CAF1 mice. The CFU-S of their blood, marrows, and spleens were assayed at intervals from days 10 through 56. The effects of splenectomy performed on day 14 or 42 on the numbers of CFU-S in the blood and marrow were also studied. On day 10 after treatment with 89Sr both the cellularity and CFU-S of the marrow were markedly decreased. Later, especially during the third week after treatment, marrow cellularity increased and by day 56 had returned to 74 percent of normal; the concentration of marrow CFU-S also increased but by day 56 had attained a level of only one-third normal. Thus, replenishment of the marrow's CFU-S lagged behind the repletion of its cellularity. Spleen and blood CFU-S were elevated throughout the 56 days. The number of splenic CFU-S was highest at day 10, decreased somewhat by day 21, and remained remarkably stable thereafter. After splenectomy there was a significant decline in the content of both blood and marrow CFU-S, whereas the reverse occurred in the "cold" 88Sr-treated control group. The results of these studies suggest that in the 89Sr-irradiated animal the spleen is transformed from a trapper to the prime supplier of CFU-S and that in normal mice the spleen may suppress marrow CFU-S proliferation. An inverse relationship between the size of the pool of mature granulocytes and the number of CFU-S was found, suggesting that the granulocyte compartment may, at least in part, play a role in the regulation of CFU-S proliferation.

It has been found possible to test ferritin concentrations in the reticulum and hemopoietic cells from human bone marrow by an immunoradiometric assay. Ferritin concentration in healthy test persons amounts to 0.92 +/- 0.38 ng/microgram protein in the reticulum and 0.084 +/- 0.031 ng/microgram protein in hemopoietic cells. In healthy test persons about 90% of the ferritin is localized in the reticulum and about 10% in the hemopoietic cells. The ferritin concentration in the reticulum is decreased in patients having iron deficiency anemia. In these patients only 50-70% of the bone marrow ferritin is localized in the reticulum. Bone marrow ferritin was characterized by a combination of anion-exchange chromatography using Sephadex A-50 and an immunoradiometric assay. Marrow ferritin from healthy persons is eluted at chloride concentrations between 200 and 300 mM. The anion-exchange chromatographic properties of ferritin in the reticulum and hemopoietic cells are identical.

Monoclonal antibodies (MoAbs) have been prepared recently that recognize the three cell-surface receptors for the Fc portion of immunoglobulin (Ig), termed Fc gamma RI (MoAb 32.2), Fc gamma R II (MoAb IV-3), and Fc gamma R III (MoAb 3G8) that are expressed on selected subsets of non-T lymphocyte peripheral blood leukocytes. In the blood, Fc gamma R I is expressed exclusively on monocytes and macrophages, Fc gamma R II on granulocytes, mononuclear phagocytes, platelets, and B cells, and Fc gamma R III on granulocytes and natural killer (NK) cells. We have examined the expression of these molecules on normal bone marrow (BM) cells and on leukemia cells from the blood and/or BM in order to determine their normal ontogeny as well as their distribution on leukemic cells. BM was obtained from six normal volunteers and from 170 patients with newly diagnosed acute leukemia. Normal BM cells were found to express Fc gamma R I, II, and III with the following percentages: 40%, 58%, and 56%, respectively. Cell sorting revealed that both Fc gamma R I and Fc gamma R II were detectable on all subclasses of myeloid precursors as early as myeloblasts. Cell sorting experiments revealed that 66% of the granulocyte-monocyte colony-forming cells (CFU-GM) and 50% of erythroid burst-forming units (BFU-E) were Fc gamma R II positive with only 20% and 28%, respectively, of CFU-GM and BFU-E were Fc gamma R I positive. Acute myeloid leukemia (AML) cells expressed the three receptors with the following frequency (n = 146): Fc gamma R I, 58%; Fc gamma R II, 67%; and Fc gamma R III, 26% of patients. Despite the fact that Fc gamma R I is only expressed on monocytes among blood cells, AML cells without monocytoid differentiation (French-American-British [FAB]M1, M2, M3, M6) were sometimes positive for this receptor. However, Fc gamma R I was highly correlated with FAB M4 and M5 morphology (P less than .001). Fc gamma R II was also correlated with FAB M4 and M5 morphology (P = .003). Cells from 11 patients with acute lymphoblastic leukemia were negative for Fc gamma R I, but six cases were positive for Fc gamma R II and III (not the same patients). These studies demonstrate that Ig Fc gamma R are acquired during normal differentiation in the BM at or before the level of colony-forming units. In addition, we show that acute leukemia cells commonly express Fc gamma R.

Pre-mRNA from bone marrow of rabbits enriched in erythroid cells was analyzed by T1 and pancreatic RNase treatment and poly(U)- and poly(A)-Sepharose chromatography to contain poly(A)-, oligo(U)- and double stranded sequences. The length of the poly(A)- and oligo(U)-sequences was determined by polyacrylamide gel electrophoresis using poly(A)- and oligo(U)-standards of defined length. Poly(A) from poly(A)+pre-mRNA isolated according to the method of Holmes and Bonner shows a size distribution between 40 and 130 nucleotides with an average of 75 nucleotides. Hot phenol extraction according to Georgiev et al. leads to a smaller size of about 25 nucleotides. The oligo(U)-segment consists of 80% U and is about 25 nucleotides long. Poly(A)+ pre-mRNA of about 12000--16000 nucleotides posseses 1--2 oligo(U)-units and one double strand of about 70 nucleotide pairs. Most (greater than 90%) of the oligo(U)-and the double stranded sequences are localized at least 1700 nucleotides away from the 3'terminus. Double strands were investigated with respect to their reannealing behaviour. The material consists of two types of double strands: 20% which reassociate at a cot/2 cot/2 of 1.3 . 10(-4) represent only one or a few types of double strands, the remaining 80% reassociate at a cot/2 of about 7 . 10(-2) and are more complex. Under hybridization conditions pre-mRNA molecules are able to self-annealation. 10% of the sequences become RNase stable.

Specific binding sites for erythropoietin (Epo) were shown in normal and anemic rat bone marrow cells using [125I]labeled human recombinant Epo. When rats were treated once or several times with phenylhydrazine or malotilate, or by phlebotomy, the serum Epo level determined by RIA began to increase rapidly. Thereafter, both the number of erythroid colony-forming unit (CFU-E)-derived colonies and the Epo binding capacity of bone marrow cells increased almost simultaneously in response to induced anemic states, suggesting that the amount of Epo binding in bone marrow cells may reflect in vivo erythropoiesis. Scatchard analysis of the binding data from normal rats revealed the presence of a single class of binding sites (Kd = 0.18 +/- 0.04 nM, 38 +/- 5 sites/cell). In anemic states, the apparent average receptor number per cell increased (52-62 sites/cell) without changing in binding affinity toward Epo. Furthermore, [125I]Epo was cross-linked to the cell surface molecule of approximately 165 kd in nonreducing conditions and 75 kd in reducing conditions. Autoradiographic analysis indicated that Epo receptors were distributed on immature erythroid cells. Proerythroblasts were the most heavily labeled, whereas orthochromatic erythroblasts and cells of myeloid and lymphoid lineages were not labeled. Calculations based on Scatchard and autoradiographic analysis showed that proerythroblasts have 390 receptor sites per cell, twice as many as basophilic or polychromatophilic erythroblasts have. These results are consistent with the stage-specific action of Epo in physiological differentiation of erythroid cells.