Persistence of inhibitory activity against normal bone-marrow cells during remission of acute leukemia

Clinical Implications of Inflammation in Acute Myeloid Leukemia

Recent advances in the description of the tumor microenvironment of acute myeloid leukemia, including the comprehensive analysis of the leukemic stem cell niche and clonal evolution, indicate that inflammation may play a major role in many aspects of acute myeloid leukemia (AML) such as disease progression, chemoresistance, and myelosuppression. Studies on the mechanisms of resistance to chemotherapy or tyrosine kinase inhibitors along with high-throughput drug screening have underpinned the potential role of glucocorticoids in this disease classically described as steroid-resistant in contrast to acute lymphoblastic leukemia. Moreover, some mutated oncogenes such as RUNX1, NPM1, or SRSF2 transcriptionally modulate cell state in a manner that primes leukemic cells for glucocorticoid sensitivity. In clinical practice, inflammatory markers such as serum ferritin or IL-6 have a strong prognostic impact and may directly affect disease progression, whereas interesting preliminary data suggested that dexamethasone may improve the outcome for AML patients with a high white blood cell count, which paves the way to develop prospective clinical trials that evaluate the role of glucocorticoids in AML.

DPP4 truncated GM-CSF and IL-3 manifest distinct receptor-binding and regulatory functions compared with their full-length forms

Dipeptidylpeptidase 4 (DPP4/CD26) enzymatically cleaves select penultimate amino acids of proteins, including colony stimulating factors (CSFs), and has been implicated in cellular regulation. To better understand the role of DPP4 regulation of hematopoiesis, we analyzed the activity of DPP4 on the surface of immature blood cells and then comparatively assessed the interactions and functional effects of full-length (FL) and DPP4 truncated factors [(T)-GM-CSF and- IL-3] on both in vitro and in vivo models of normal and leukemic cells. T-GM-CSF and T-IL-3 had enhanced receptor binding, but decreased CSF activity, compared to their FL forms. Importantly, T-GM-CSF and T-IL-3 significantly, and reciprocally, blunted receptor binding and myeloid progenitor cell proliferation activity of both FL-GM-CSF and FL-IL-3 in vitro and in vivo. Similar effects were apparent in vitro using cluster forming cells from patients with Acute Myeloid Leukemia (AML) regardless of cytogenetic or molecular alterations and in vivo utilizing animal models of leukemia. This suggests that DPP4 T-molecules have modified binding and functions compared to their FL counterparts and may serve regulatory roles in normal and malignant hematopoiesis.

In vitro evaluation of the haemopoietic defect of CD34+ cells from patients with acute myeloid leukaemia in first remission

Haemopoietic cells from patients with acute myeloid leukaemia (AML) in first complete remission (CR1) show in vitro a haemopoietic defect and a decreased expansion potential. To better characterize this haemopoietic defect, CR1 AML and normal CD34+ cells were analysed for immunophenotype, viability, cell cycle and progenitor content before and during expansion culture in stroma-conditioned medium supplemented with cytokines. The production of haemopoiesis inhibitor by patient cells and the influence of high concentrations of stem cell factor (SCF) and Flt3-ligand (FL) on cell survival and ex vivo expansion potential were also studied. Before expansion, patient CD34+ cells showed viability and cell-cycle phase distribution similar to normal but lower percentages of CD34+DR- or CD34+CD38- cells and lower progenitor content. After 48 h of culture +/-30% of patient cells had died regardless of the cytokine combination used, whereas only 15% of normal cells died. After 7 d of culture, viability and cell cycle analyses showed comparable data for normal and patient samples. Co-culture of patient and normal cells did not show any evidence for haemopoiesis inhibitor production by patient cells. Even at high cytokine concentrations, a low progenitor expansion and a decrease in CD34+ cell numbers was observed for patient samples in contrast to normal samples. In conclusion, CR1 AML CD34+ cells showed excessive early cell mortality. No evidence for cell-cycle arrest or haemopoiesis inhibitor production was shown. SCF and FL used at high concentrations did not correct the patient cell expansion defect.

Hypoplastic acute leukemia: description of eight cases and search for hematopoietic inhibiting activity

Hypoplastic acute leukemia (HAL) is characterized by pancytopenia and by hypocellularity of the bone marrow. The marrow contains equal to or more than 30% myeloblasts. Absence of tissue infiltrates and/or tumor masses is mandatory. Eight patients are described here. They do not fit into the FAB classification for either acute nonlymphocytic leukemia (ANLL) or myelodysplastic syndrome (MDS), except for one patient who subsequently proved to have a chronic myelomonocytic leukemia (CMML). The median age is 65 years. Two patients, including the CMML patient, are alive, 22 and 6 months from diagnosis. Six patients have died. The median survival is 8 months. Normal bone marrow cells cultured either with HAL sera or with HAL peripheral blood mononuclear cells as feeders and exogenous GM-CSF yielded subnormal CFU-GM counts. This might indicate inhibitory activity of HAL serum and defective stimulatory activity of HAL peripheral blood mononuclear cells.

Long-term bone marrow damage after chemotherapy for acute myeloid leukaemia does not improve with time

Thirteen patients with acute myeloid leukaemia (AML) who had been in unmaintained complete remission for at least 5 years following successful chemotherapy, were studied by marrow culture techniques regularly for periods of up to 5 years. In 10 patients, short-term clonal assay revealed the incidence of granulocyte-macrophage progenitor cells (GM-CFC) to be at the lower limit of the normal range; but three showed wide fluctuations in GM-CFC numbers. Moreover the generation of GM-CFC in long-term bone marrow culture (LTBMC) was impaired in eight of nine evaluable patients. These results suggest that, despite normal blood counts, impairment of haemopoiesis persists in patients who are long-term survivors of AML, and this does not improve with the passage of time.

Thrombocytosis as a presenting feature of acute lymphoblastic leukemia in childhood

To determine the incidence of thrombocytosis at presentation in acute lymphoblastic leukemia (ALL), medical records of all children diagnosed at the Children's Hospital of Pittsburgh from 1980 to 1987 were reviewed. Out of 217 such patients, 7 (3.2%) had platelet counts greater than 400,000/mm3. All of the seven were boys compared with a male:female ration of 1.4:1 in the entire ALL population. Other than sex, no characteristics were clearly associated with thrombocytosis, including white blood cell count, hemoglobin, lymphoblast morphology, and immunologic or chromosomal markers. Apart from ALL, no inflammatory or infectious process which might have caused a thrombocytosis, was detected in any of these patients. The period of induction therapy was notable for the preservation of platelet counts greater than 20,000/mm3 in all patients. However, of the seven children with thrombocytosis, two had major induction complications: one, a cavernous sinus thrombosis; and the other, gastrointestinal bleeding with duodenal perforation. We conclude that thrombocytosis at diagnosis can be seen in children, particularly boys, with ALL. Based on small numbers, this group of patients may be at risk for major events during induction therapy. Large numbers, longer follow-up, and platelet function studies on similar patients will be of interest.

Biologic characteristics and treatment of acute nonlymphocytic leukemia in children. Report of the ANLL Strategy Group of the Childrens Cancer Study Group

Today approximately 75 per cent of children with ANLL can be induced into a complete remission and approximately 40 per cent will have an event-free survival for more than 3 years, irrespective of whether they received a bone marrow transplantation or chemotherapy after induction. In order to achieve these results very intensive therapy is required. The morbidity and mortality of treatment are high. The length of therapy needed after induction of remission is not known. Whether or not maintenance therapy is required is perhaps related most directly to the intensity of the therapy employed. Similarly, the role of bone marrow transplantation in patients in first remission, treatment of CNS leukemia, and treatment of chloromas are controversial. There is general agreement that WBCs over 100,000, acute monoblastic leukemia in infants less than 2 years of age, and certain chromosomal abnormalities are associated with a poor prognosis. Although there has been a dramatic improvement in the treatment of ANLL over the past 15 years, stratification of therapy based on biologic parameters, and alteration of treatment based on the early responses to treatment may be required before further advances will be made.

Platelets and neoplasia

Numerous platelet abnormalities have been recognized in animals with malignancy. Because platelets play a key role in hemostasis, it is vital that clinicians recognize those neoplastic conditions that are associated with platelet disorders. A review of these platelet abnormalities, their underlying pathophysiology, and treatment is presented in this article.

The predictive value of in-vitro techniques in acute non-lymphocytic leukemia

Bone marrow aspirates obtained from 27 patients with acute non-lymphocytic leukemia (ANLL) was cultured at the time of presentation, during remission and at relapse. Growth patterns were assessed throughout the patient's clinical course. The percentage of Ia-positive progenitor cells was assayed by a complement-dependent cytotoxicity assay. The percentage of cells in S phase was measured by a tritiated thymidine suicide index. Growth patterns of leukemic bone marrow samples at presentation showed varied numbers of clusters but only rare colonies. This was not predictive of clinical course. Growth patterns of bone marrow in complete remission from ANLL often had depressed colony numbers. However, some patients in remission had bone marrow growth patterns that approached or reached normal colony numbers, suggesting elimination of residual leukemia. The percentage of cells that expressed Ia antigen at presentation, during remission and at relapse varied widely and was not predictive of long-term remission or early relapse. The percentage of cells in S phase was also highly variable and not predictive of clinical course. At presentation the S-phase percentage correlated with the percentage of cells expressing Ia antigen. However, there was no such correlation during remission.

In-vitro granulopoiesis in adult acute lymphoblastic leukemia at various phases of the disease

We used the in-vitro agar culture technique to monitor the granulopoiesis in 68 adult patients with ALL during the course of their disease. Bone marrow cells were cultured from 42 patients at diagnosis, 26 patients in relapse, 36 patients in early remission and 31 patients in full remission. The results of culture growth were characterized by sparse or no growth at diagnosis. No inhibition of normal CFU-C by leukemic cells was demonstrated by co-culture experiments. In relapsed marrows with blasts exceeding 60%, the culture results were identical to those at first presentation. The colonies grown in ALL cultures showed normal morphology with a normal granulocytic and monocytic differentiation. The colony-forming potential gradually increased following induction therapy, but there was no relationship between the CFU-C number and the percentage of blasts. The impaired granulopoiesis usually recovered once a remission was obtained and remained normal throughout the remission period. In some instances, cultures were performed within a short period prior to relapse or carried out more than one occasion during stable remission, wide fluctuations in CFU-C incidences were observed. Our study indicates that the CFU-C assay in ALL is useful for monitoring the in-vitro granulopoietic activity at various phases of the disease, but is of limited value in predicting the response to treatment as well as in determining the remission-relapse status.

Myeloid progenitors in acute non-lymphocytic leukemia: prognostic value in remission

The prognostic value of in vitro cloning of bone marrow and blood cells was tested in 32 patients with acute non-lymphocytic leukemia (ANLL) at various stages of disease. Using placental conditioned medium (PCM) as a stimulus and panoptical staining methods for the analysis of colony morphology, four different growth types could be distinguished at presentation. Poor response to colony-stimulating activity (GM-CSF) in vitro seemed to be associated with poor survival. Probably due to low patient numbers, this association could not be proven statistically. During remission a progressive decrease of morphologically normal colonies was recognized in the bone marrow and peripheral blood. Thus by in vitro cloning methods the quality of remission could be substantiated.

Pretreatment of cytokinetics in acute myelogenous leukemia. Age-related prognostic implications

To determine the clinical and biologic relevance of cellular kinetics in leukemia, DNA flow cytometric analysis was performed on bone marrow biopsy specimens from 148 previously untreated adult patients with acute myelogenous leukemia. The proportion of cells in synthesis, second growth, and mitosis (S + G2M) ranged from 4% to 33% with a median of 14%. The overall incidence of complete remission was not affected by the pretreatment cell cycle distribution. As in earlier studies, there was a marked decline in remission rate with advancing age from 73% for patients age less than or equal to 50 yr to 50% for those greater than 50 (P less than 0.01). Although not affecting remission induction overall, an increasing proportion of cells in S + G2M phase was favorable in patients under the age of 50 yr, but was associated with a progressive decline in remission rate in older patients (P = 0.01). This age-related divergent effect of cell cycle kinetics on initial response to therapy was confined to the less favorable subgroup of patients with karyotypic abnormalities, whereas patients with normal diploid cytogenetics had a consistently higher response rate regardless of proliferative activity. A positive correlation was also observed between percent of S + G2M cells and the proportion of diploid metaphases in young patients, contrasting with a negative correlation in the older age group. Our observations strongly suggest that the well-recognized prognostic effect of age on remission induction is not entirely host-mediated, but is at least partly an expression of disease-intrinsic differences between young and older patients.

CFU-gm colony formation of peripheral blood and bone marrow in adult acute leukemia at presentation, during remission, and at relapse

Granulocyte/macrophage colony-forming unit (CFU-gm) formation was studied simultaneously in bone marrow and peripheral blood of 52 previously untreated adult patients with acute non-lymphocytic (ANLL) and 36 with acute lymphoblastic leukemia (ALL). They were followed during induction therapy at monthly intervals while in remission and in 19 ANLL and 22 ALL cases, until relapse. Patients showing a decreased colony number in the marrow but normal or increased colony numbers in the peripheral blood had a high probability of entering remission. Non-responding patients displayed an opposite pattern. The higher the degree of marrow repopulation with granulocytic progenitor cells after induction treatment, the longer remission duration and survival for ANLL patients and the longer survival for ALL patients. CFU-gm formation returned to normal in the early stages of complete remission, but then declined progressively. At ANLL and ALL relapse, colony growth was reduced markedly while cluster formation remained normal. The number of marrow colonies and clusters in ANLL were significantly higher at first and second relapse compared to the growth pattern at first presentation. A similar trend had been observed in ALL, suggesting a selection advantage.

Treatment of dysmyelopoietic/leukemic syndromes with myelofibrosis and megakaryocytic hyperplasia with large doses of cytosine arabinoside

Eight patients with inaspiratable bone marrows due to significant degrees of fibrosis were treated with high dose cytosine arabinoside because of either documented or suspected coexistent acute leukemia. The peripheral blood counts returned to normal in 7 patients. Remissions were short lived and bone marrow abnormalities persisted suggesting that consolidation therapy should be administered to these patients as soon as their peripheral blood counts are normalized.

CFU-C abnormalities and cytochemical defects in bone marrow of adult patients during remission of acute leukemia

Twenty-three adult patients in complete remission (CR) from acute leukemia were investigated for the steady-state bone marrow (BM) CFU-C concentration and the cytochemical findings of neutrophils and monocytes. There was considerable variation in CFU-C concentrations among patients. Patients with abnormality high or low values tended to relapse earlier. Repeated assays revealed constant CFU-C values in individual long-term cases of remission (4 cases). One case of M4 (myelomonocytic) and the case of M5b (monocytic) leukemia revealed a complete lack of nonspecific esterase activity in CR monocytes as well as initial leukemic promonocytes; they also showed abnormally high or low concentrations of CFU-C and relapsed early. This finding suggests that hematopoiesis in CR bone marrow occurs from abnormal stem cells common to initial, acute leukemic clones in such cases.

HLA-DR human histocompatibility leukocyte antigens-restricted lymphocyte-monocyte interactions in the release from monocytes of acidic isoferritins that suppress hematopoietic progenitor cells

Acidic isoferritins, which under normal conditions are released from monocytes and macrophages, have a suppressive effect in vitro on granulocyte-macrophage, erythroid, and multipotential hematopoietic progenitor cells. Cell interactions modulating the release of acidic isoferritin-inhibitory activity (AIFIA) from human monocytes were investigated using the bone marrow granulocyte-macrophage progenitor cells as a target cell assay for assessing AIFIA. Monocytes, in the absence of T lymphocytes, released AIFIA when allowed to condition culture medium at 10(4) or higher concentrations of monocytes/ml. However, subpopulations of T lymphocytes modulated the release of AIFIA from monocytes. OKT8+- and OKT4+-T lymphocytes were obtained from E-rosette-positive lymphocytes by using T lymphocyte subset-specific monoclonal antibodies in either a complement-dependent cytotoxicity test to select negatively for the cells or by selection using a "panning" procedure. OKT8+-T lymphocytes suppressed completely and OKT4+-T lymphocytes enhanced the constitutive release of AIFIA from monocytes. OKT4+ lymphocytes also induced the release of AIFIA from concentrations of 10(3) monocytes/ml which did not release measurable amounts of AIFIA by themselves. The release of AIFIA from monocytes involved HLA-DR+-monocytes and -T lymphocytes. Pulsing monocytes with monoclonal antibodies to framework determinants on HLA-DR molecules, in the absence of complement, did not influence the constitutive release of AIFIA. Pulsing monocytes or T lymphocyte subpopulations with such antibodies, in the absence of complement, blocked the suppressing and inducing activities of the appropriate subpopulations of T lymphocytes. Monoclonal antibodies to common determinants shared by HLA-A, B, and C molecules did not block these cellular interactions. Treating monocytes and T lymphocytes in a complement-dependent cytotoxicity test with dilutions of the anti-HLA-DR antibodies that did not block the cellular interactions removed the populations of monocytes constitutively releasing AIFIA and the T lymphocyte subsets modulating this release. Modulation of the release of AIFIA from monocytes by T lymphocyte subpopulations required the use of autologous cells, cells from HLA-identical siblings, or unrelated donors matched for HLA-DR. Matching for only one HLA haplotype gave partial responses and this was seen in testing cells from related individuals as well as among unrelated test combinations. These cellular interactions were not detected with HLA-DR-incompatible cells differing for two HLA-DR antigens. Admixture of such HLA-DR- incompatible allogeneic cells did not interfere with the regulation of AIFIA release in the autologous cell interactions. Thus, release of AIFIA from monocytes is restricted genetically by HLA-DR at the level of T lymphocyte-monocyte interactions. The genetic determinants on the HLA-class II molecules that induce stimulation in vitro in mixed lymphocyte culture (i.e., HLA-D), however, were not involved in this effort.

Colony assays of hematopoietic progenitor cells and correlations to clinical situations

The production of blood cells is a dynamic process that is noticeably aberrant during disease. The availability of colony assays in vitro that allow detection of hematopoietic stem and progenitor cells for the neutrophil, monocyte-macrophage, erythroid and/or megakaryocyte lineages has been of importance for the present understanding of the mechanisms controlling the proliferation, self-renewal capacity, and differentiation of morphologically nonrecognizable immature cells which give rise to the mature progeny circulating in the blood. It is through the use of these assays that the existence of potentially relevant stimulatory and inhibitory feedback interactions has been demonstrated. Abnormalities in these interactions, which may be of significance during leukemia and related disorders, have been uncovered. This communication will discuss regulatory interactions detected via the colony assays, their potential relevance physiologically and pathologically, and the use of these assays for diagnosis, prognosis, and for monitoring the clinical status of patients.

Remission of acute myelogenous leukemia in elderly patients with prior refractory dysmyelopoietic anemia

Refractory dysmyelopoietic anemia (RDA) is a myeloproliferative disorder usually of elderly patients which often evolves into acute myelogenous leukemia (AML). AML in such patients is usually considered untreatable with standard aggressive chemotherapy in part because these patients are often elderly, but primarily because of the concern that the bone marrow of these patients no longer has a residual stem cell to repopulate the bone marrow following chemotherapy-induced aplasia. The authors treated three patients (ages 72, 69, and 62 years, respectively) with intensive chemotherapy after RDA evolved into AML. Each patient had been pancytopenic for 3 to 15 months prior to their transition to AML. At the onset of therapy for AML, all were severely pancytopenic with greater than 50% myeloblasts in the bone marrow. All patients had bone marrow aplasia by day 14 after chemotherapy with a complete bone marrow remission and normal peripheral counts by day 26. These data suggest that intensive chemotherapy of AML with prior RDA may result in complete bone marrow remission.

Biosynthesis of ferritin subunits from different cell lines of HL-60 human promyelocytic leukaemia cells and the release of acidic isoferritin-inhibitory activity against normal granulocyte-macrophage progenitor cells

Biosynthesis of acidic isoferritins was investigated in human promyelocytic HL-60 cells, characterized by diploid (2C), tetraploid (4C) and mixed diploid--tetraploid (2C-4C) DNA cell lines. The three cell lines were studied for the biosynthesis of ferritin and its subunits and for the release of acidic isoferritin-inhibitory activity against normal CFU-GM before and after addition of DMSO. While the tetraploid and mixed diploid--tetraploid cell lines synthesized more H-(Mr = 21) than L-subunits (Mr = 19) after induction, the tetraploid line synthesized more H-subunit before and after induction, compared to the diploid line. The release of acidic isoferritin-inhibitory activity was greater before than after induction in both cell lines, but the tetraploid cell line released more acidic isoferritin-inhibitory activity consistent with its greater production of Mr = 21 subunit. However, after induction no inhibitory activity could be detected from the diploid cells and much less activity was detected with the tetraploid cells, suggesting that differentiation caused a decrease in production of acidic isoferritin-inhibitory activity.

Acidic isoferritin inhibitory activity: a normal granulopoietic regulator within long term mouse bone marrow cultures

Long term murine bone marrow cultures maintain orderly granulopoiesis for several months. Assay of cell free supernatant obtained at weekly feedings from control cultures demonstrated endogeneously produced acidic isoferritin inhibitory activity. Addition of 10(9) M acidic isoferritin inhibitory activity to long term cultures gave a trend toward fewer nonadherent cells and fewer colony forming units-granulocyte/macrophage (CFU-GM) per flask, but this was not statistically significant. Media conditioned by each fraction of velocity sedimentation separated non-adherent cells gave two discrete peaks of inhibition at 5.6 and 6.8-9 mm/h, respectively. Acidic isoferritin inhibitory activity was restricted to the sharp peak at 5.6 mm/h. Media conditioned by each fraction of velocity sedimentation separated adherent layer cells did not contain assayable acidic isoferritin inhibitory activity. Tests for an endogeneously produced soluble inactivator of acidic isoferritin inhibitory activity were negative. The constitutive production and release of acidic isoferritin inhibitory activity by a restricted population of cells within long term marrow cultures supports the concept of this molecule as a normal hematopoietic regulator.

Kinetics of colony-forming cells (CFU-c) in adult acute leukemia and their prognostic relevance

The in vitro growth pattern of bone marrow and peripheral blood in soft-agar cultures was studied in 50 previously untreated patients with adult acute leukemia. Patients were followed from time of first diagnosis, during induction treatment, in remission at various time intervals, at relapse and during subsequent re-induction therapy. The distribution of granulopoietic progenitor cells was analysed to determine their prognostic significance for remission incidence, remission duration and survival. All patients revealed an abnormal growth. ANLL patients showing a decreased clone number in the marrow but an increased number of clones in the peripheral blood, had a significant higher probability to enter remission and a significant longer remission than those having clones within normal range at first presentation. On the contrary, ALL patients responding to induction treatment, had a better colony and cluster growth in the bone marrow than those failing to respond. No significant correlation was found between in vitro growth and survival. It is concluded that colony-forming cells of both bone marrow and peripheral blood seems to be of some value in predicting the response rate and length of remission in ANLL and ALL, and in possibly selecting patients with a high chance to respond to current cytostatic regimens.

Studies of myelopoiesis in vitro on blood and bone marrow cells of patients with acute leukemia in long-term remission

In vitro myelopoiesis in a group of ten patients with acute leukemia (6 AML, 1 APML, 3 ALL) in long-term remission has been studied. The patients remained in first stable remission for at least 4 years and maintenance therapy had been completed in all patients except one. In the patients, colony formation of bone marrow cells after 7 days of incubation was significantly increased compared to a representative control group. The proliferation of microclusters after 3 incubation days was also markedly enhanced, and accelerated proliferation of all aggregates (microclusters, macroclusters and colonies) could be demonstrated in culture with the patients' bone marrow cells. The use of autologous feeder layers and autologous serum showed no inhibitory effect on colony formation. The proportion of eosinophil colonies formed with the patients' bone marrow cells was in the normal range. In contrast to the high proliferation capacity of bone marrow precursor cells the CFU-c number of peripheral blood was significantly decreased in the patients' group. No significant correlation between CFU-c number of bone marrow and blood cells could be found. The colony stimulating activity of the patients' peripheral mononuclear cells was normal compared to healthy controls. We conclude from this study that even in long-term remission of acute leukemia certain in vitro abnormalities exist in myelopoietic proliferation and regulation.

Relationship of cell-cycle expression of Ia-like antigenic determinants on normal and leukemia human granulocyte-macrophage progenitor cells to regulation in vitro by acidic isoferritins

An association has been established between human Ia-like (Ia) antigenic determinants, expression during DNA synthesis on granulocyte-macrophage colony forming cells (CFU-GM) and the regulatory action of acidic isoferritins in vitro. Treatment of human bone marrow cells with monoclonal-anti-Ia-like (Ia) plus complement inhibited colony and cluster formation by approximately 50% but did not affect pre-CFU-GM. Reduction of colonies and clusters was similar whether bone marrow cells were exposed to anti-Ia plus complement, high specific activity tritiated thymidine ((3)HTdr) or acidic isoferritins. No further decrease was apparent with (3)HTdr or acidic isoferritins after Ia-antigen(+) CFU-GM were removed, or with anti-Ia plus complement or acidic isoferritins after DNA synthetic phase (S-phase) CFU-GM were removed. Anti-Ia, without complement, did not reduce colony or cluster formation but did block the inhibitory action of acidic isoferritins. A relationship existed between Ia antigens and the activity of acidic isoferritins in the following ways: (a) The apparent loss of Ia-antigens from CFU-GM by 5 h in culture at 37 degrees C, but not at 27 degrees or 4 degrees C, was associated with nonresponsiveness to inhibition with acidic isoferritins, (b) Ia-antigen(-), noncycling pre-CFU-GM that were insensitive to acidic isoferritins could generate a population of Ia-antigen(+) cycling CFU-GM in vitro that were responsive to inhibition by acidic isoferritins, and (c) nondetectability of Ia-antigens on CFU-GM from patients with leukemia was associated with nonresponsiveness to inhibition by acidic isoferritins. These results implicate Ia-antigen(+) progenitor cells in the regulation of myelopoiesis in vitro and demonstrate that absence of Ia-antigens on patient CFU-GM is associated with imbalances in normal regulatory interactions in vitro. These findings may be of relevance to normal regulation and to the progression of leukemia.

Hypoplastic acute leukemia

There have been few reports of acute leukemia presenting with a hypocellular bone marrow. All patients diagnosed as having acute leukemia were identified during a recent six-year interval who had blast cells plus promyelocytes of greater than 30% and marrow cellularity of needle biopsy less than or equal to 50%. Of 195 patients analyzed, 15 (7.7%) fulfilled the criteria. Ten patients were men and five women; the median age was 68 years with a range of 40-82. Seven complained of fatigue of 6-12 months duration, five were seen with occult infection, and three were asymptomatic. Hepatosplenomegaly was absent in 93% and none had lymphadenopathy. Fourteen patients were pancytopenic with median leukocyte count at presentation of 1.5 X 10(9)/liter, hemoglobin of 9.0 g/dl, and platelet count of 55 X 10(9)/liter. Circulating blast cells were not observed in ten patients; in the other five they were less than 0.7 X 10(9)/liter. The morphology of all cases appeared myeloid and Auer rods were seen in three patients; however, in one the peroxidase was negative. Classification according to FAB criteria revealed ten to be M1, three to be M2, one M4, and one L2. Median survival of the entire group was seven months. Of seven patients receiving no chemotherapy, two survived longer than 1 year (14, 24.5 months), one is alive at 7+ months, and the median survival was seven months. Eight patients with life-threatening complications received various combination regimens including an anthracycline, cytosine arabinoside, 6-thioguanine, vincristine, and prednisone. Five died of treatment complications; two achieved durable complete remission and are free of disease at 17 and 27 months. It can be concluded that hypoplastic acute leukemia is a distinct nosologic entity affecting primarily older patients with myeloid leukemia. Remission induction therapy in patients who are seriously ill has a low success rate, and in some patients prolonged survival is possible with supportive care alone.

Growth and differentiation patterns of human acute non lymphoid leukemia in diffusion chambers before and after treatment

Diffusion chambers (DC) were used to culture bone marrow of ANLL patients firstly at the onset, secondly in complete remission and thirdly in the relapse of the disease. At the onset of the disease an increase in cellular concentration mainly due to the granulocytic differentiation was observed in DC in all ANLL patients, in contrast to no growth in ANLL patients in complete remission and in relapse. The DC technique reveals a marked pathological pattern of proliferation in every phase of ANLL, at the presentation, in complete remission and in relapse.

Identification of leukemia-associated inhibitory activity as acidic isoferritins. A regulatory role for acidic isoferritins in the production of granulocytes and macrophages

Acidic isoferritins have been identified as leukemia-associated inhibitory activity (LIA), which suppresses colony and cluster formation of colony-forming unit-granulocyte macrophages from normal donors but not from patients with leukemia. LIA was detected in all ferritin preparations tested, including ferritin isolated from normal heart, spleen, liver, and placental tissues, and from the spleens of patients with chronic myelogenous leukemia and Hodgkin's disease. Purified preparations of LIA were composed almost entirely of acidic isoferritins, as determined by immunoassay, radioimmunoassay, and isoelectric focusing. The inhibitory activity in the LIA and ferritin samples was inactivated by a battery of antisera specific for ferritin, including those prepared against acidic isoferritins from normal heart and spleen tissues from patients with Hodgkin's disease, and those previously absorbed with basic isoferritins. Antisera absorbed with acidic isoferritins did not inactivate the inhibitory activity. Separation of LIA and chronic myelogenous leukemia and normal spleen ferritin by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing confirmed that the regions of peak inhibitory activity corresponded in each to an apparent molecular weight of approximately 550,000 and to a pI value of 4.7. Similar physicochemical characteristics included inactivation by methods that dissociate ferritin molecules into subunits and by treatment with trypsin, chymotrypsin, pronase, and periodate. The purified preparations were extremely stable to heat treatment. The glycoprotein nature of the inhibitory activity was substantiated because it bound to concanavalin A-Sepharose and was eluted off by alpha-methyl mannose. Inhibitory activity of the activity of the acidic isoferritins was detected at concentrations as low as 10(-17)-10(-19) M and iron saturation did not appear to be necessary for its action. These results implicate acidic isoferritins in the regulation of normal myelopoiesis and suggest a role for them in the progression of leukemia.

Comparison of 7 and 12 day bone marrow CFUc culture in adult acute non lymphoblastic leukaemia

Bone marrows from 17 patients with acute nonlymphoblastic leukaemia (ANLL) were serially cultured on semisolid agar during periods of intensive remission induction chemotherapy and during remission. Of 12 patients achieving remission, six showed recovery of 7 and 12 day colony forming units (CFUc) culture to normal. However, in four of the six patients, recovery was short-lived with reappearance of typically leukaemic culture patterns while still in remission by bone marrow and peripheral blood criteria. In individual patients, serial 7 day cultures frequently showed persisting or recurring leukaemia-associated patterns while 12 day cultures were normal. This study confirms the heterogeneity observed in the cultural characteristics of the CFUc in acute non lymphoblastic leukaemia. Bone marrow cultures in patients with ANLL following intensive remission induction chemotherapy appear to provide a more reliable indication of persisting leukaemia or early relapse if they are interpreted earlier at 7 days.

Human myeloid leukaemic cell interactions in vitro with normal myeloid colonies

To determine whether myeloid leukaemic cells could inhibit normal myeloid colony formation, leukaemic cells at concentrations ranging from 0.5 to 8 X 10(6)/ml were co-cultured in agar but separated by a 1 ml underlayer from 10(5) low-density (less than 1.077 g/ml) nonadherent normal marrow cells. Inhibition of normal-marrow myeloid colony formation occurred regularly at high cell concentrations (8 X 10(6)) at a leukaemic:normal cell ratio of 80:1. This suppression persisted with addition of indomethacin (10(-6)M). On the other hand, both low leukaemic cell numbers and irradiated leukaemic cells frequently stimulated normal colony growth. No inhibitor of colony growth could be detected in leukaemic-conditioned media, and absorption of colony-stimulating activity (CSA) with leukaemic cells improved CSA activity. These experiments point to the difficulty in unravelling the effect of leukaemic cells on normal haemopoiesis (both inhibitory and stimulatory) by in vitro agar culture.

Isolation and biochemical characterization of leukemia-associated inhibitory activity that suppresses colony and cluster formation of cells

Leukemia-associated inhibitory activity suppresses colony and cluster formation in vitro cells derived from granulocyte-macrophage progenitor cells of normal donors. It does not inhibit these same progenitor cells from patients with leukemia and it may contribute to the proliferative advantage leukemia cells appear to possess over normal hematopoietic cells during acute leukemia. The inhibitory activity was isolated by a combination of procedures including: ultracentrifugation, Sephadex G-200, carboxymethylcellulose, SDS-polyacrylamide gel electrophoresis, thin-layer and preparative isoelectric focusing and concanavalin A-Sepharose. Leukemia-associated inhibitory activity was characterized as a glycoprotein. it was inactivated by trypsin, chymotrypsin, pronase and periodate treatment. It bound to and was eluted by alpha-methylmannose from concanavalin A-Sepharose columns and had an apparent Mr range of 450-550 000 and an isoelectric focus value between pH 4.6 and 4.9. Crude leukemia associated inhibitory activity was temperature sensitive but the more purified preparations were heat stable.

Predicting relapse of human leukemia by means of premature chromosome condensation

We attempted to determine whether the technique of premature chromosome condensation (PCC) could be used to predict relapse in patients with acute leukemia in complete remission. Nineteen patients received chemotherapy and were studied serially with the PCC technique. Of the 19 patients in this pilot study, 14 relapsed, and the PCC technique predicted relapse in 11 of these 14. The median time from an elevation in the fraction of G1 cells in the late G1 phase (a high proliferative-potential index) to the development of clinical evidence of relapse was 3.5 months. On the other hand, the median time from a low proliferative-potential index to relapse or to the end of the study was eight months. The incidense of false-positive or false-negative measurements was low. Two patients had high index values just before chemotherapy, and remission was estimated to be prolonged by 2.5 and six months by our therapeutic protocol. These results suggest that the PCC technique is useful and accurate in the early prediction of relapse in human leukemia.