Treatment-free remission following frontline nilotinib in patients with chronic myeloid leukemia in chronic phase: results from the ENESTfreedom study

The single-arm, phase 2 ENESTfreedom trial assessed the potential for treatment-free remission (TFR; i.e., the ability to maintain a molecular response after stopping therapy) following frontline nilotinib treatment. Patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase with MR^4.5 (BCR-ABL1⩽0.0032% on the International Scale (BCR-ABL1^IS)) and ⩾2 years of frontline nilotinib therapy were enrolled. Patients with sustained deep molecular response during the 1-year nilotinib consolidation phase were eligible to stop treatment and enter the TFR phase. Patients with loss of major molecular response (MMR; BCR-ABL1^IS⩽0.1%) during the TFR phase reinitiated nilotinib. In total, 215 patients entered the consolidation phase, of whom 190 entered the TFR phase. The median duration of nilotinib before stopping treatment was 43.5 months. At 48 weeks after stopping nilotinib, 98 patients (51.6% 95% confidence interval, 44.2–58.9%) remained in MMR or better (primary end point). Of the 86 patients who restarted nilotinib in the treatment reinitiation phase after loss of MMR, 98.8% and 88.4%, respectively, regained MMR and MR^4.5 by the data cutoff date. Consistent with prior reports of imatinib-treated patients, musculoskeletal pain-related events were reported in 24.7% of patients in the TFR phase (consolidation phase, 16.3%).

Activation of the complement cascade enhances motility of leukemic cells by downregulating expression of HO-1

As a crucial arm of innate immunity, the complement cascade (ComC) is involved both in mobilization of normal hematopoietic stem/progenitor cells (HSPCs) from bone marrow (BM) into peripheral blood and in their homing to BM. Despite the fact that ComC cleavage fragments alone do not chemoattract normal HSPCs, we found that leukemia cell lines as well as clonogenic blasts from chronic myeloid leukemia and acute myeloid leukemia patients respond robustly to C3 and C5 cleavage fragments by chemotaxis and increased adhesion. This finding was supported by the detection of C3a and C5a receptors in cells from human malignant hematopoietic cell lines and patient blasts at the mRNA (reverse transcriptase-polymerase chain reaction) and protein level (fluorescence-activated cell sorting), and by the demonstration that these receptors respond to stimulation by C3a and C5a by phosphorylation of p42/44 and p38 mitogen-activated protein kinases (MAPK), and protein kinase B (PKB/AKT). We also found that inducible heme oxygenase 1 (HO-1) is a negative regulator of ComC-mediated trafficking of leukemic cells, and that stimulation of leukemic cells by C3 or C5 cleavage fragments activates p38 MAPK, which downregulates HO-1 expression, rendering cells more mobile. We conclude that activation of the ComC in leukemia/lymphoma patients (for example, as a result of accompanying infections) enhances the motility of malignant cells and contributes to their spread in a p38 MAPK-HO-1-dependent manner. Therefore, inhibition of p38 MAPK or upregulation of HO-1 by small-molecule modulators would have a beneficial effect on ameliorating cell migration-mediated expansion of leukemia/lymphoma cells when the ComC becomes activated.

Immunoablation and autologous hematopoietic stem cell transplantation in the treatment of new-onset type 1 diabetes mellitus: long-term observations

The activity of the autoimmune mechanism underlying type 1 diabetes mellitus (T1DM) can be suppressed when immunoablation and autologous hematopoietic stem cell transplantation (AHSCT) are applied early in the course of the disease. We report here a single centre experience with this treatment modality. Twenty-four patients underwent a AHSCT preceded by immunoablative conditioning with high-dose cyclophosphamide and anti-thymocyte globulin. During the 52-month median time of follow-up 20 out of 23 patients (87%) remained for at least 9.5 months without the use of exogenous insulin. The median time of T1DM remission for these patients was 31 months (range of 9.5-80 months). Among the patients available for follow-up (n=20), four remain insulin free (for 80, 61, 42 and 34 months). The average glycated hemoglobin (HbA1c) concentrations were 10.9% at diagnosis, 5.9% at 1 year, 6.4% at 2 years, 6.8% at 3 years and 7.1% at 4 years after AHSCT. No severe complications of diabetes were seen, however one of the patients died of pseudomonas sepsis in the course of neutropenia after AHSCT. AHSCT leads to a remission of T1DM with good glycemic control in the vast majority of patients, with the period of remission lasting over 5 years in some patients.

High-dose melphalan and autologous hematopoietic stem cell transplantation in primary amyloidosis: single-center results

BACKGROUND

Systemic immunoglobulin light-chain amyloidosis (AL) is a plasma cell dyscrasia resulting in multisystem organ failure and death. Autologous hematopoietic stem-cell transplantation (ASCT) has been widely used to treat patients with AL. However, treatment-related mortality remains high and reported series are subject to selection bias.

METHODS

To define the role of patient selection in stem cell transplantation, we evaluated 24 consecutive AL patients transplanted at our center.

RESULTS

Complete hematologic response was achieved in all 20 patients surviving >100 days posttransplantation. The 1-year overall survival (OS) rate after ASCT was 78.5%. The 5- and 10-year progression-free and OS rates were 57% and 47%, respectively. Treatment-related deaths owing to cardiovascular problems occurred in 16% of cases.

CONCLUSION

ASCT for AL amyloidosis can be safely performed in experienced transplantation centers, and increased risk is associated mainly with cardiovascular system involvement.

Allogeneic hematopoietic stem cell transplantation in solid organ transplant recipients: a retrospective, multicenter study of the EBMT

We conducted a questionnaire survey of the 565 European Society for Blood and Marrow Transplantation centers to analyze the outcome of allogeneic hematopoietic stem cell transplantation (alloSCT) in recipients of solid organ transplantation (SOT). We investigated 28 patients with malignant (N = 22) or nonmalignant diseases (N = 6), who underwent 31 alloSCT procedures: 12 after kidney, 13 after liver and 3 after heart transplantation. The incidence of solid organ graft failure at 60 months after first alloSCT was 33% (95% confidence interval [CI], 16-51%) for all patients, 15% (95% CI, 2-40%) for liver recipients and 50% (95% CI, 19-75%) for kidney recipients (p = 0.06). The relapse rate after alloSCT (22%) was low following transplantation for malignant disorders, despite advanced stages of malignancy. Overall survival at 60 months after first alloSCT was 40% (95% CI, 19-60%) for all patients, 51% (95% CI, 16-86%) for liver recipients and 42% (95% CI, 14-70%) for kidney recipients (p = 0.39). In summary, we show that selected SOT recipients suffering from hematologic disorders may benefit from alloSCT and experience enhanced long-term survival without loss of organ function.

Update on the Incidence of Metamizole Sodium-Induced Blood Dyscrasias in Poland

Metamizole sodium (metamizole) is a popular non-opioid analgesic and a common non-prescription product in Poland. Controversy exists regarding the level of risk of agranulocytosis or aplastic anaemia associated with its use. Two previous pharmacovigilance studies conducted in Poland found the risk was low. Twenty-four of the 25 haematology centres that provide specialist care for the 30 million adults in Poland participated in this prospective 12-month study. Twenty-one cases of agranulocytosis, 48 of aplastic anaemia, 15 of neutropenia and 11 of pancytopenia were reported. Of these cases, three (two agranulocytosis; one aplastic anaemia) were judged as being possibly related to metamizole. Crude estimates of the rate of agranulocytosis and aplastic anaemia associated with metamizole were 0.16 and 0.08 cases/million person-days of use, respectively. Ongoing national safety surveillance in Poland shows that, despite the possibility of drug-induced blood dyscrasias with metamizole, the risk is very low.

Indications for allogeneic stem cell transplantation in chronic lymphocytic leukemia: the EBMT transplant consensus

The aim of this project was to identify situations where allogeneic stem cell transplantation (allo-SCT) might be considered as a preferred treatment option for patients with B-cell chronic lymphocytic leukemia (CLL). Based on a MEDLINE search and additional sources, a consented proposal was drafted, refined and approved upon final discussion by an international expert panel. Key elements of the consensus are (1) allo-SCT is a procedure with evidence-based efficacy in poor-risk CLL; (2) although definition of 'poor-risk CLL' requires further investigation, allo-SCT is a reasonable treatment option for younger patients with (i) non-response or early relapse (within 12 months) after purine analogues, (ii) relapse within 24 months after having achieved a response with purine-analogue-based combination therapy or autologous transplantation, and (iii) patients with p53 abnormalities requiring treatment; and (3) optimum transplant strategies may vary according to distinct clinical situations and should be defined in prospective trials. This is the first attempt to define standard indications for allo-SCT in CLL. Nevertheless, whenever possible, allo-SCT should be performed within disease-specific prospective clinical protocols in order to continuously refine transplant indications according to new developments in risk assessment and treatment of CLL.

RNA and protein evidence for haplo-insufficiency in Diamond-Blackfan anaemia patients with RPS19 mutations

The genetic basis of Diamond-Blackfan anaemia (DBA), a congenital erythroid hypoplasia that shows marked clinical heterogeneity, remains obscure. However, the fact that nearly one-quarter of patients harbour a variety of mutations in RPS19, a ribosomal protein gene, provides an opportunity to examine whether haplo-insufficiency of RPS19 protein can be demonstrated in certain cases. To that end, we identified 19 of 81 DBA index cases, both familial and sporadic, with RPS19 mutations. We found 14 distinct insertions, deletions, missense, nonsense and splice site mutations in the 19 probands, and studied mutations in 10 patients at the RNA level and in three patients at the protein level. Characterization of the mutations in 10 probands, including six with novel insertions, nonsense and splice site mutations, showed that the abnormal transcript was detectable in nine cases. The RPS19 mRNA and protein in CD34+ bone marrow cells identified haplo-insufficiency in three cases predicted to have one functional allele. Our data support the notion that, in addition to rare DBA patients with the deletion of one allele, the disease in certain other RPS19 mutant patients is because of RPS19 protein haplo-insufficiency.

Triple transplantation of autologous peripheral blood stem cells each time following conditioning with 100 mg/m2 of melphalan for multiple myeloma patients in poor performance status

Approximately one third of multiple myeloma patients (below 60 years) are diagnosed either in advanced disease or with significant comorbidities. Many other patients referred to transplant centers have already been heavily pretreated with multiple courses of various conventional chemotherapies. These patients are frequently in bad or even grave clinical condition; they are unlikely to survive standard high-dose melphalan (200 mg/m(3)) chemotherapy and autologous hematopoietic stem cell transplantation. Palumbo et al reported a protocol for elderly patients that utilized reduced conditioning (melphalan 100 mg/m(2) three times at 2-month intervals, each time supported by autologous hematopoietic rescue). We have used this protocol as a start to develop a method to induce a remission in the aforementioned subgroup of myeloma patients. Patients with stage III disease and WHO performance status 2 or higher are treated with one or two cycles of cyclophosphamide (2 to 4 g/m(2)) and undergo peripheral blood stem cells collection. Subsequently, they are treated with three to four doses of melphalan (100 mg/m(2)) at 8- to 12-weeks intervals each time supported by infusion of peripheral blood stem cells. To date 13 patients have been entered into the protocol. With one exception of transiently stable disease, the remaining patients obtained at least partial remission and three, complete remission. The compliance was good and better with each subsequent course. For half of the patients the problem was a short duration of response. This method when developed may offer a new treatment alternative for a subgroup of high-risk multiple myeloma patients.

Evaluation of relative anti-myeloma activity of high-dose melphalan followed by the first peripheral blood stem cell transplantation, as compared with the second transplantation, and to VAD chemotherapy

Current treatment in multiple myeloma consists of three courses of chemotherapy in low doses with subsequent hematopoietic stem cell mobilization to the peripheral blood using high-dose cyclophosphamide, collection and conditioning with high-dose chemotherapy (melphalan) followed by retransplantation of autologous peripheral blood stem cells (PBSCT). Only a few studies compare the effects of different phases of therapy on parameters, such as monoclonal immunoglobulin level and the presence of malignant CD38(+) and CD56(+) cells in blood and marrow. The aim of this study was to compare the effects of these two major phases of treatment (conventional and high dose) in the same patients, and furthermore, to compare the effects of the second course of high-dose therapy followed by PBSCT with the effects of the first one. Fifteen patients were included in the study. On average, conventional chemotherapy only slightly reduced the values of all disease markers. In contrast, high-dose therapy resulted in a dramatic effect, rapidly normalizing the values of all parameters. The effects of second PBSCT were only modest compared to the first. These data suggest that high-dose therapy is an efficient method to reduce tumor load in multiple myeloma. Conventional-dose chemotherapy may be simply a waste of time for some patients and may be either omitted or administered after high-dose therapy to consolidate remission.

Reduced number and altered morphology of microglial cells in colony stimulating factor-1-deficient osteopetrotic op/op mice

The numerical density of microglial cells is reduced by 47% in the corpus callosum, by 37% in the parietal cortex and by 34% in the frontal cortex of mice mutant at the op locus which are totally devoid of colony stimulating factor-1 (CSF-1), the major growth factor for macrophages. Moreover, microglia in the frontal cortex of the op/op mice are smaller and have shorter cytoplasmic processes compared to control mice. Study suggests that CSF-1 plays a role in vivo in the formation and maturation of microglia and has little or no effect on perivascular cells.

The effect of chemo- and chemoimmunotherapy on the presence of circulating melanoma cells in peripheral blood. Preliminary results

Reverse transcription and polymerase chain reaction (RT/PCR) with primers specific for tyrosinase allow for a new method of early detection of individual melanoma cells in peripheral blood. Using this test the effect of chemo- and chemoimmunotherapy on the spread of early micrometastatic cancer cells has been evaluated. No significant correlations have been found between RT/PCR results on the one hand and stage of disease, a kind of the therapy protocol used and usage of the therapy as an adjuvant or palliative on the other hand. Thus, although the RT/PCR test for detection of circulating individual melanoma cells might help in identification of minimal residual disease in some patients, it has no application for routine staging of more advanced disease and in monitoring the response to therapy.

The effect of chemo- and chemoimmunotherapy on the presence of circulating melanoma cells in peripheral blood. Preliminary results

Reverse transcription and polymerase chain reaction (RT/PCR) with primers specific for tyrosinase allow for a new method of early detection of individual melanoma cells in peripheral blood. Using this test the effect of chemo- and chemoimmunotherapy on the spread of early micrometastatic cancer cells has been evaluated. No significant correlations have been found between RT/PCR results on the one hand and stage of disease, a kind of the therapy protocol used and usage of the therapy as an adjuvant or palliative on the other hand. Thus, although the RT/PCR test for detection of circulating individual melanoma cells might help in identification of minimal residual disease in some patients, it has no application for routine staging of more advanced disease and in monitoring the response to therapy.

[Subcutaneous immunoglobulin infusion in antibody deficiency substitution of a patient sensitized to intravenous immunoglobulins. Case report]

Patients with severe form of common variable immunodeficiency require chronic immunoglobulin substitution. However, intravenous Ig administration may not be possible in some of them because of serious anaphylactoid reactions. It has been suggested that such patients may tolerate well Ig administration by subcutaneous infusion. A case is described (originally with IgG level of 53 mg/dl) who reacted with anaphylactic shock to intravenous immunoglobulin and now for more than 7 months at 1-2 week intervals receives immunoglobulin by subcutaneous infusion without any adverse reactions and maintaining IgG level above 400 mg/dl. In contrast to the period proceeding immunoglobulin substitution, the patient remains free of bacterial infection during last 7 months.

The use of bone-marrow-derived fibroblastoid cells and fresh bone marrow in the treatment of bone defects: an experimental study

Bone-marrow aspirate (containing bone progenitor cells), in vitro expanded autologous bone-marrow-derived stromal fibroblastoid cells, and a combination thereof were tested for the potential to fill bone defects. They were compared to grafts of fresh autologous bone or allogeneic devitalized bone. Mandibular defects in rabbits were chosen for this study. The best results were obtained with a combination of in vitro expanded bone-marrow-derived stromal fibroblastoid cells and fresh autologous bone marrow or fresh autologous marrow alone. The effects of these two grafts were similar to grafts of fresh autologous bone and significantly superior to grafts of devitalized allogeneic bone providing only a bone matrix. The in vitro expanded marrow stromal cells induced very significant bone ingrowth, and their effects were only slightly inferior to fresh autologous bone but were superior to devitalized allogeneic bone. These studies suggest that bone marrow is a good source of osteogenic cells both for immediate transplantation and for in vitro expansion and subsequent transplantation.

Cytokine regulation of the macrophage (M phi) system studied using the colony stimulating factor-1-deficient op/op mouse

The macrophage (M phi) lineage is more complex than other myeloid lineages of hematopoietic cells and includes strikingly different end cells such as Kupffer cells, alveolar M phi, histiocytes, serosal M phi, synovial type A cells, microglia, osteoclasts, and possibly dendritic cells. These cells are formed under the influence of primary M phi growth factors such as colony stimulating factor (CSF)-1, granulocyte-M phi (GM)-CSF, and interleukin-3. The dissection of the system has been greatly facilitated by discovery of the osteopetrotic op/op mouse, which has a spontaneous knockout of the gene for CSF-1 and possesses generalized but differential deficiency of various local subpopulations of M phi. Studies using this model indicate that the M phi lineage is split into CSF-1-dependent and CSF-1-independent cells that are largely independently regulated. These contribute variably to different local populations and have largely, but not totally, overlapping functions. Both CSF-1 and GM-CSF are responsible for transition of cells of the M phi lineage from bone marrow to blood, and from blood to tissues, and have a critical extramedullary role. Regulation of the M phi system by CSF-1 is complex, with some local populations dependent on circulating CSF-1 and some supported exclusively by locally produced CSF-1. Colony stimulating factor-1-dependent M phi are not required for the generation of a specific immune response. Instead, most likely they play a regulatory role in various tissue reactions including responses to bacterial infection, neoplasia, and atherosclerosis. A hypothetical major role of CSF-1-independent M phi is to collaborate with lymphocytes in mounting an immune response. These issues need further exploration using animals with knockouts of genes for other M phi growth and activation factors and their receptors.

Colony-stimulating factor 1-dependent resident macrophages play a regulatory role in fighting Escherichia coli fecal peritonitis

Osteopetrotic op/op mice have less than 5% of the normal number of macrophages in the peritoneal cavity (W. Wiktor-Jedrzejczak, A. Ahmed, C. Szczylik, and R.R. Skelly, J. Exp. Med. 156:1516-1527, 1982). Fecal peritonitis was induced by intraperitoneal injection of 0.5 ml of 5% autoclaved feces in saline along with Escherichia coli grown from feces of mice of the same colony and added in doses ranging between 10 and 10(6) CFU. Such infection led to a septic shock and either was lethal within 24 h or became cured without additional treatment of the mice. The op/op mice survived administration of 30-times-smaller doses of bacteria compared with their normal littermates. Analysis of the kinetics of cellular changes in the peritoneal cavity associated with such infection revealed that this increased susceptibility of macrophage-deficient mice cannot be explained by a direct role of macrophages in combating the infection. Instead, it appeared that the increased susceptibility to fatal fecal peritonitis was most likely due to delayed and impaired recruitment of neutrophils to the site of infection in mutant mice. The increased susceptibility of the op/op mice to E. coli fecal peritonitis was not due to their possible increased sensitivity to endotoxin, since the mutant mice tolerated lipopolysaccharide doses more than twice those tolerated by control littermates. On the other hand, their susceptibility to exogenous tumor necrosis factor alpha and interleukin-1 alpha was increased. Both mutant op/op and control mice were able to survive secondary challenge with 10(6) E. coli (administered along with feces) lethal for both types of mice on primary challenge. These data suggest that colony-stimulating factor 1-dependent resident peritoneal macrophages play a role in controlling primary infection by recruiting neutrophils and are not required for efficient response to secondary infection.

Impaired tumor growth in colony-stimulating factor 1 (CSF-1)-deficient, macrophage-deficient op/op mouse: evidence for a role of CSF-1-dependent macrophages in formation of tumor stroma

Macrophages have been suggested to play a major role in the immune response to cancer. They have also been suggested to stimulate the formation of tumor stroma and to promote tumor vascularization. The availability of the op/op mouse, which has no endogenous colony-stimulating factor 1 (CSF-1) and which possesses a profound macrophage deficiency, provides a new model to verify these notions. Subcutaneous growth of transplantable Lewis lung cancer (LLC) is markedly impaired in the op/op mice compared with normal littermates. Treatment of tumor-bearing op/op mice with human recombinant CSF-1 corrects this impairment. Histological analysis of tumors grown in op/op and normal mice revealed marked differences. Tumors grown in op/op mice display a decreased mitotic index and pronounced necrosis, particularly hemorrhagic. Moreover, particularly in the op/op tumors, peculiar sinusoid-like abortive vessels (not filled with blood) have been observed. These tumors, in contrast to tumors grown in normal mice, are almost deprived of regular arteries and veins. In contrast to tumors grown in normal mice, they exhibit almost no Sirius red-stained collagenous fibers and Gomori silver-stained reticular fibers. Our data suggest that the CSF-1-dependent macrophage subpopulation missing in op/op mice plays a primary role in supporting tumor stroma formation and tumor vascularization in murine LLC tumors.

Potentiation of antitumor effects of tumor necrosis factor alpha and interferon gamma by macrophage-colony-stimulating factor in a MmB16 melanoma model in mice

The efficacy of systemic infusion of recombinant human macrophage-colony-stimulating factor (M-CSF) in combination with local treatment with human recombinant tumor necrosis factor (TNF) alpha and mouse recombinant interferon (IFN) gamma was studied in vivo on a subclone of B16 melanoma (MmB16) in mice. Short-term intravenous administration of M-CSF at a dose of 10(6) units daily had no antitumor effect in vivo. Similarly, local treatment of tumor with TNF alpha (5 micrograms daily) did not produce any therapeutic effect. However, simultaneous administration of the same dose of TNF alpha with IFN gamma (1000 units daily) resulted in a synergistic effects manifested by the retardation of tumor growth. Addition of systemic infusion of M-CSF to the local therapy with TNF alpha and IFN gamma induced further augmentation of antitumor efficacy and delayed progression of MmB16 melanoma. The strengthened antitumor effect of combination therapy including M-CSF, TNF alpha and IFN gamma was most probably due to the increased release of monocytes from the bone marrow, their recruitment into the site of tumor growth and subsequent local stimulation of their antitumor activity.

Granulocyte-macrophage colony-stimulating factor corrects macrophage deficiencies, but not osteopetrosis, in the colony-stimulating factor-1-deficient op/op mouse

The op mutation in the mouse is in the coding region of the colony-stimulating factor-1 (CSF-1) gene, prevents formation of biologically active factor, and, thus, results in generalized macrophage deficiency and, in osteopetrosis, secondary to deficiency of osteoclasts. Although a few macrophages and osteoclasts are present in these mutants, it was not clear whether the inability of endogenous granulocyte-macrophage CSF (GM-CSF) to compensate for the absence of CSF-1 was due to the limitations of biological activity of this molecule or to its inability to reach respective target populations. In this study, we examined whether sc GM-CSF in large doses (20-40 micrograms/mouse.day) for 3 weeks would correct some or all of the deficiencies observed in mutant mice. All organ macrophage populations tested (liver, spleen, thymus, marrow, pleural, and peritoneal cavity) were significantly increased, reaching levels exceeding those observed in normal mice. Restoration of peritoneal and pleural macrophage populations by sc GM-CSF is of particular interest, because it was not previously observed in op/op mice treated with sc CSF-1. In contrast, there was no indication of increased bone resorption, no appearance of osteoclasts, and no tooth eruption in response to GM-CSF treatment. These data suggest that GM-CSF is able to compensate for the absence of CSF-1 during macrophage formation, but is unable to play a similar role in osteoclast differentiation.

In vivo role of macrophage growth factors as delineated using CSF-1 deficient op/op mouse

Total absence of CSF-1 in the op/op mouse leads to a profound and generalized deficiency of macrophages and to osteopetrosis subsequent to the absence of osteoclasts. These observations confirm that CSF-1 is a genuine regulator of macrophage and osteoclast formation in vivo. Further studies in affected animals have shown that the CSF-1 absence variably affects macrophage differentiation stages and different organ macrophage populations, and that functionally competent macrophages are produced in low numbers without CSF-1, presumably under the influence of GM-CSF and IL-3. The op/op mice have increased levels of both endogenous GM-CSF and IL-3, which apparently are not fully able to compensate for the absence of CSF-1. Macrophage deficiencies but not osteoclast deficiencies in the op/op mouse could be completely corrected by exogenous GM-CSF, while exogenous CSF-1 corrects both osteoclast and macrophage deficiencies, but only in those tissues which could be reached by CSF-1 from the circulation. Despite severe quantitative macrophage deficiencies, the op/op mice demonstrate normal in vivo phagocytosis and immune functions suggesting that CSF-1 dependent macrophages do not contribute significantly to those processes in vivo. On the other hand, the op/op mice demonstrate severe secondary deficiencies of TNF-alpha, IL-1 alpha, and G-CSF suggesting that major function of CSF-1 dependent macrophages is the release of monokines.

CSF-1 deficiency in the op/op mouse has differential effects on macrophage populations and differentiation stages

Osteopetrosis and the absence of colony-stimulating factor 1 (CSF-1) in op/op mice are associated with decreased cellularity of the bone marrow (to one tenth of the normal), a very significant reduction in the number of cells recovered from peritoneal, pleural, and alveolar lavages, moderate leukopenia, and a slight decrease in the number of cells per spleen and thymus. Furthermore, op/op mice possess deficiencies in the number of macrophages in various organs. These cells are apparently absent in the bone marrow, severely reduced (5%-15% of the normal number) in peritoneal and pleural cavities and in the lungs. In addition, a marked decrease in the frequency and total number of circulating monocytes is present (5% of the normal). The deficiency of macrophages is less severe in the liver, spleen, and thymus of op/op mice (approximately 30% of those seen in normal). There is a concomitant redistribution of macrophage progenitor cells (granulocyte-macrophage colony-forming units, CFU-GM) in op/op mice from the marrow to the spleen and liver, associated with an increased sensitivity to interleukin 3 (IL-3). Their total number is decreased at least threefold compared to control mice. Moreover, op/op mice have at least a fivefold reduction in the total number of day-11 spleen colony-forming units (CFU-S) associated with their redistribution to the spleen and liver. These data suggest that the macrophage system in op/op mice is reduced at all levels tested, that is, at the level of mature macrophages, the level of progenitors, and the level of stem cells, whereas the redistribution of progenitor and stem cells could be viewed as a secondary consequence of osteopetrosis. Furthermore, these data suggest that macrophage dependency in vivo on CSF-1 is limited and different in various organs. Particularly in the liver, spleen, and thymus, other growth factors may significantly compensate for CSF-1 deficiency. Based on the relative decrease in the number of CFU-GM in the op/op mice, it appears that the population size of these progenitors is less dependent on CSF-1 than the hematopoietic stem cell population size as evidenced by the day-11 CFU-S assay. The day-11 CFU-S population is severely reduced in op/op mice, suggesting a physiological involvement of CSF-1 in expanding its size. These data provide evidence that CSF-1, besides acting on the final and intermediate stages of macrophage maturation, may also play a role in early stages of hematopoiesis.

Distinct in vivo functions of two macrophage subpopulations as evidenced by studies using macrophage-deficient op/op mouse

The op/op mice totally lack macrophage growth factor colony-stimulating factor (CSF)-1 and thus, by definition are completely depleted of CSF-1-dependent functions of the macrophage cell lineage. Moreover, they possess a severe and generalized macrophage deficiency. However, residual macrophages of these mice should still have normal CSF-1-independent functions. Studies designed to elucidate this issue have revealed that op/op mice are capable of normal in vivo phagocytic function and demonstrate normal humoral and cellular response postimmunization with sheep red blood cells. However, release of monokines such as tumor necrosis factor and granulocyte CSF following administration of endotoxin is severely impaired in op/op mice as compared with littermate controls. These studies suggest that the CSF-1-dependent macrophage population (absent in the op/op mouse) is primarily responsible for regulatory functions of these cells mediated by monokines, while the CSF-1-independent macrophage population (present in the op/op mouse) is primarily responsible for the classical macrophage functions in immunity such as phagocytosis, antigen processing and presentation.

Administration of colony stimulating factor-1 corrects some macrophage, dental, and skeletal defects in an osteopetrotic mutation (toothless, tl) in the rat

The toothless (tl/tl) mutation in the rat results in a paucity of osteoclasts and osteopetrosis that cannot be corrected by bone marrow transplantation. In the present study we demonstrate that tl/tl rats also have profound deficiencies of femoral, peritoneal, and pleural cavity macrophages. Furthermore, the macrophage colony stimulating activity of post-endotoxin sera from tl/tl rats is substantially reduced, suggesting that, as in the case of the op mutation in mice, the basis of the tl mutation is a deficiency of the macrophage growth factor, colony stimulating factor-1 (CSF-1). Consistent with this suggestion, treatment of tl/tl rats from birth for up to six weeks with CSF-1 reduced the osteopetrosis, increased body weight, and permitted tooth eruption. In addition, CSF-1 treatment induced large numbers of osteoclasts in tl/tl bones and macrophages in the peritoneal cavity and bone marrow. Persistence of metaphyseal sclerosis, however, indicated that the disease was not totally corrected by this treatment. These studies indicate that the basis of the tl mutation is most likely another CSF-1 deficiency, and further emphasize the role of this growth factor in osteoclast differentiation.

A pregnancy defect in the osteopetrotic (op/op) mouse demonstrates the requirement for CSF-1 in female fertility

Correlative evidence suggests that maternal production of the mononuclear phagocyte growth factor colony stimulating factor-1 (CSF-1) regulates placental development. In order to study the role of CSF-1 in pregnancy the fertility of CSF-1-less osteopetrotic (op/op) mutant mice was investigated. Homozygous mutant crosses (op/op x op/op) were consistently infertile. As expected, op/op males were almost completely fertile when crossed with heterozygous females. Surprisingly, op/op females when mated to heterozygote males were fertile, although at a rate that was 46% of the rate for +/op females x op/op males. These data suggest that CSF-1 is required for pregnancy. However, a maternal CSF-1 source is not absolutely necessary in that pregnancies involving +/op fathers were partially rescued, suggesting that +/op fetuses and/or +/op seminal fluid provides CSF-1 or CSF-1-induced factors which compensate for the absence of maternally produced CSF-1. Despite the complete absence of CSF-1 in the uterus and placenta of op/op mice placental weights were normal, suggesting that proliferation of decidual cells and trophoblasts, both of which express the CSF-1 receptor, may not be solely regulated by CSF-1. Histochemical staining for F4/80 antigen was used to identify macrophages in the uterus and placenta. Uterine macrophages could not be detected in virgin op/op mice although they were abundant in +/op uteri. Interestingly, macrophages could be detected in op/op uteri as uncharacteristically rounded cells in early gestation, however, they were not maintained and no macrophages were apparent beyond Day 14 of pregnancy in op/op mice. Further studies in the osteopetrotic mouse will be useful in delineating those functions required for pregnancy that are regulated by CSF-1.

Correction by CSF-1 of defects in the osteopetrotic op/op mouse suggests local, developmental, and humoral requirements for this growth factor

Mice that are mutant at the op locus have a severe deficiency of mononuclear phagocytes due to an inactivating mutation in the CSF-1 (macrophage colony-stimulating factor, M-CSF) gene. op/op mice are toothless, possessing skeletal abnormalities, a low body weight, and compromised fertility; they are osteopetrotic due to a deficiency of osteoclasts. The congenital osteopetrosis, toothless phenotype, osteoclast deficit, and the defects in splenic and femoral macrophages were corrected by routes of administration of human recombinant CSF-1 that maintained normal circulating CSF-1 concentrations. Early restoration of circulating CSF-1 was required for rescue of the toothless phenotype, but only partially restored body weight. In contrast, the deficiencies of pleural and peritoneal cavity macrophages and the reduced female fertility were not corrected by restoration of circulating CSF-1. These results suggest that although circulating CSF-1 is required for osteoclast and macrophage production, local synthesis and action of the growth factor are important for certain target cell populations.

Total absence of colony-stimulating factor 1 in the macrophage-deficient osteopetrotic (op/op) mouse

Osteopetrotic (op/op) mutant mice suffer from congenital osteopetrosis due to a severe deficiency of osteoclasts. Furthermore, the total number of mononuclear phagocytes is extremely low in affected mice. Serum, 11 tissues, and different cell and organ conditioned media from op/op mice were shown to be devoid of biologically active colony-stimulating factor 1 (CSF-1), whereas all of these preparations from littermate control +/+ and +/op mice contained the growth factor. The deficiency was specific for CSF-1 in that serum or conditioned media from op/op mice possessed elevated levels of at least three other macrophage growth factors. Partial correction of the op/op defect was observed following intraperitoneal implantation of diffusion chambers containing L929 cells, which in culture produce CSF-1 as their sole macrophage growth factor. No rearrangement of the CSF-1 gene in op/op mice was detected by Southern analysis. However, in contrast to control lung fibroblasts, which contained 4.6- and 2.3-kilobase CSF-1 mRNAs, only the 4.6-kilobase species was detected in op/op cells. An alteration in the CSF-1 gene is strongly implicated as the primary defect in op/op mice because they do not contain detectable CSF-1, their defect is correctable by administration of CSF-1, the op locus and the CSF-1 gene map within the same region of mouse chromosome 3, their CSF-1 mRNA biosynthesis is altered, and the op/op phenotype is consistent with the phenotype expected in a CSF-1 deficient mouse.

Interferon-gamma-treated K562 target cells distinguish functional NK cells from lymphokine-activated killer (LAK) cells

In vitro incubation of the erythroleukemic cell line K562 with interferon-gamma (IFN-gamma) renders these cells relatively resistant to natural killer (NK) cell lysis. However, such treatment does not alter their sensitivity to LAK cell lysis. Thus, the lytic susceptibility of interferon-gamma-treated K562 (I-K562) cells to LAK cells as opposed to its relative resistance to NK cell lysis provides a functional assay to help distinguish these two types of effector cells. The relative resistance of I-K562 for NK cell-mediated lysis was not secondary to the release of soluble factors or the frequency of Leu-19+, CD3+ T cells, residual IFN-gamma, or expression of MHC Class I molecules. Coincubation of I-K562 cells with NK or LAK cells overnight did not appreciably change the pattern of lytic responses against K562 and I-K562 target cells. However, incubation of PBMC in vitro with I-K562 but not native K562 in the presence of r-IL-2 leads to a marked decrease in the generation of LAK cells. The inhibition of LAK cell generation was not secondary to differences in the consumption of bioactive levels of IL-2. Differences in the lytic capability of NK and LAK effector cells suggest heterogeneity among cells that mediate such non-MHC-restricted lysis. Use was made of cells from a patient with a large granular lymphocyte lymphoproliferative disease (greater than 85% Leu-19+) to determine if such cells could be used to distinguish clonal population of cells which would represent NK or LAK cell function. Of interest was the finding that such cells, even after incubation in vitro with IL-2, showed lytic function representative of NK cells but not LAK cells. Data concerning the inhibition of LAK cell generation by I-K562 cells have important implications for future therapeutic trials of IFN-gamma and IL-2 in the treatment of human malignancies.

Postirradiation recovery of haemopoiesis in Steel mutant mice

The recovery of haemopoiesis in Steel mutant mice following 1 Gy sublethal irradiation is described. Steel homozygotes (S1/S1) did not display the abortive phase of erythropoietic recovery while the secondary phase of erythropoietic recovery was more pronounced in S1/S1 than in control (+/+) animals. On the contrary, the neutrophilopoietic recovery in S1/S1 mice was defective only during the secondary phase of recovery. Steel heterozygotes (S1/+) manifested similar, albeit less pronounced, defects. In the course of studies of recovery of eosioniphils it was observed that neither wild-type nor mutant animals expressed the abortive rise. Moreover, the kinetics of recovery of eosinophils was essentially different from both erythropoietic and neutrophilopoietic recovery, and the preirradiation level was reached in both normal and mutant animals on day 60 postirradiation as opposed to 24 and 35 days for erythropoiesis and neutrophils respectively.

Multiple lineage colony growth from human marrow in plasma clot diffusion chambers

Marrow cells from ten healthy adult donors were cultured in plasma clot diffusion chambers implanted intraperitoneally into mice. Host animals were conditioned by two injections of phenylhydrazine and 600 cGy of x-rays. Cultures (5 X 10(4) cells/chamber) were continued for between 2 and 40 days and the chambers were retransplanted into new host animals every 5 days. Following termination of cultures, plasma clots were stained with benzidine-hematoxylin and analyzed microscopically. Erythroid, neutrophil, monocyte, eosinophil, megakaryocyte, mixed, undifferentiated, and fibroblastoid colonies were grown with neutrophil, erythroid, monocyte, and eosinophil colonies being the most frequent. A total of between 25 and 60 colonies was observed per chamber at any time point.

Omental lymphoid organ as a source of macrophage colony stimulating activity in peritoneal cavity

To test the hypothesis that the omental lymphoid organ (OLO) made by peritoneal milky spots is either a source of haemopoietic (macrophage) progenitors or growth factors we attempted to culture OLO cells in vitro in a variety of assay combinations. With the culture in vitro in semisolid agar it was found that OLO cells do not form granulocyte-macrophage or macrophage colonies in response to stimulants. However, when in the same assay marrow cells were used as the targets and OLO-related preparations as stimulants it was observed that marrow cells formed exclusively macrophage colonies. These marrow cells, in response to stimulants derived from other organs, produced granulocyte-macrophage, granulocyte and macrophage colonies. OLO-related preparations tested for macrophage-colony stimulating activity included partly purified medium conditioned by OLO cells derived from mice, either injected with endotoxin or not, and medium conditioned by OLO cells after 14 days, liquid culture in vitro. While these results were observed in Swiss mice, C3H/W mice, which are genetically endotoxin-unresponsive, failed to show this reaction. These data may suggest that the local production of macrophage-colony stimulating activity in the peritoneal cavity could be one physiological role for OLO. OLO is the first organ in adult mice identified to stimulate exclusively macrophage colony growth, and not granulocyte-macrophage or pure granulocyte colonies.