Long-term immunologic induction of donor-specific tolerance to skin allografts by bone marrow transplant in rabbits

The induction of donor-specific tolerance to skin allografts was investigated in rabbits using bone marrow transplantation techniques reported to be effective in mice. Various routes of bone marrow transplantation (i.e., intravenous, portal venous, or intraosseous) were also examined. In regimen A, the animals were treated with portal venous injection of bone marrow cells from the donor on day 0 and intravenous injection of bone marrow cells from the same donor on posttransplant day 5. In regimen B, the animals were treated with portal venous and intraosseous injections of donor bone marrow cells on day 0 and intravenous injection of bone marrow cells from the same donor on posttransplant day 5. In regimen C, the animals were given intraosseous injection of donor bone marrow cells on day 0 and intravenous injection of bone marrow cells from the same donor on posttransplant day 5. It was found that regimens B and C were more effective than regimen A in prolonging allograft survival. The results demonstrate that induction of allograft tolerance can be achieved by bone marrow transplantation in a rabbit model. This protocol deserves further study in other large animal models.     

Effect of bone marrow cells on colony-forming stromal cells in guinea pigs and on the proliferation of their cultured descendents

In the presence of irradiated bone marrow cells the efficiency of stromal colony formation increases from 0.8 +/- 0.2 to 3.6 +/- 0.4 per 10(4) explanted bone marrow cells. The growth-stimulating activity of bone marrow cells on passaged bone marrow fibroblasts depends on growth conditions of passages to which irradiated bone marrow cells are added. The response of proliferating bone marrow fibroblasts to stimulating activity of bone marrow cells is low, while addition of bone marrow cells to fibroblast cultures stimulates their proliferation.     

Generation of osteoclasts from hemopoietic cells and a multipotential cell line in vitro

Osteoclasts are the cells that resorb bone. It is generally presumed, on the basis of indirect experiments, that they are derived from the hemopoietic stem cell. However, this origin has never been established. We have developed an assay for osteoclastic differentiation in which bone marrow cells are incubated in liquid culture on slices of cortical bone. The bone slices are inspected in the scanning electron microscope after incubation for the presence of excavations, which are characteristic of osteoclastic activity. We have now incubated bone marrow cells at low density, or a factor-dependent mouse hemopoietic cell line (FDCP-mix A4) with 1,25 dihydroxyvitamin D3 (a hormone which we have previously found induces osteoclastic differentiation) with and without murine bone marrow stromal cells, or with and without 3T3 cells, on bone slices. Neither the bone marrow cells nor the bone marrow stromal cells alone developed osteoclastic function even in the presence of 1,25 dihydroxyvitamin D3. However, extensive excavation of the bone surface was observed, only in the presence of 1,25 dihydroxyvitamin D3, on bone slices on which bone marrow stromal cells were cocultured with low-density bone marrow cells or the hemopoietic cell line. Similar results were obtained when the bone marrow stromal cells were killed by glutaraldehyde fixation; 3T3 cells were unable to substitute for stromal cells. These results are strong evidence that osteoclasts derive from the hemopoietic stem cell and suggest that although mature osteoclasts possess neither receptors for nor responsiveness to 1,25 dihydroxyvitamin D3, the hormone induces osteoclastic function through a direct effect on hemopoietic cells rather than through some accessory cell in the bone marrow stroma. The failure of 3T3 cells, which enable differentiation of other hemopoietic progeny from this cell line, to induce osteoclastic differentiation suggests that bone marrow stroma possesses additional characteristics distinct from those that induce differentiation of other hemopoietic cells that are specifically required for osteoclastic differentiation.     

The relationship of bone marrow type and microvasculature to the microdistribution and local dosimetry of plutonium in the adult skeleton

Most plutonium-induced bone tumors in beagles arise in trabecular bone sites surrounded by hematopoietic tissue. The microvasculature and the relative incorporation of 241Pu (a low energy beta emitter) on trabecular bone surfaces from red and fatty marrow sites were studied in the adult beagle. The vascular volume, as determined by India ink perfusion, was about 16% in the red marrow and about 2% in the fatty marrow. The red marrow has large vascular sinusoids with a discontinuous endothelial lining whereas fatty marrow has a closed capillary bed. Plutonium concentrations on bone surfaces of red marrow sites are about 0.43 pCi/cm2/nCi/kg of injected dosage, a factor of eight greater than at fatty marrow sites (0.053 pCi/cm2/nCi/kg). The differences in the bone marrow microvasculature between red and fatty marrow help to explain differences in plutonium incorporation and local bone physiology in these skeletal sites. These observations may relate to the nonuniform distribution of plutonium-induced osteosarcomas observed in adult, long-lived mammals.     

Biological aspects of limb transplantation: I. Migration of transplanted bone marrow cells into recipient

The transplanted limb contains bone marrow tissue. The hematopoietic cells contained in the bone of the graft normally differentiate after transplantation and can be released to the recipient. The cells migrate to the recipient bone marrow cavities and lymphoid organs. This causes the immune reaction between the donor and the recipient, which develops not only in the graft itself but also in the recipient immune organs where donor bone marrow cells home. The purpose of this study was to investigate the process of migration of the hematopoietic cells from the donor limb to the recipient bone marrow cavities and lymphoid tissues. The questions the authors asked were: what is the rate of release of bone marrow cells from the transplanted bone, where do the released bone marrow cells home in the recipient, how fast are donor bone marrow cells rejected by the recipient, and can some bone marrow cells homing in the recipient tissues survive and create a state of microchimerism. Experiments were performed on Brown Norway and Lewis inbred rat strains (n = 30). Limb donors received intravenous chromium-51-labeled bone marrow cells. Twenty-four hours later, the limb with homing labeled bone marrow cells was transplanted to an allogeneic or syngeneic recipient. The rate of radioactivity of bone marrow cells released from the graft and homing in recipient tissues was measured after another 24 hours. To eliminate factors adversely affecting homing such as the "crowding effect" and allogeneic elimination of bone marrow cells by natural killer cells, total body irradiation and antiasialo-GM1 antiserum were applied to recipients before limb transplantation. In rats surviving with the limb grafts for 7 and 30 days, homing of donor bone marrow cells was studied by specific labeling of donor cells and flow cytometry as well as by detecting donor male Y chromosome. The authors found that transplantation of the limb with bone marrow in its natural spatial relationship with stromal cells and blood perfusion brings about immediate but low-rate release of bone marrow cells and their migration to recipient bone marrow and lymphoid tissues. Large portions of allogeneic bone marrow cells are rapidly destroyed in the mechanism of allogeneic elimination by radioresistant but antiasialo-GM1-sensitive natural killer cells. Some transplanted bone marrow cells remain in the recipient's tissues and create a state of cellular and DNA microchimerism. A low number of physiologically released donor bone marrow cells do not seem to adversely affect the clinical outcome of limb grafting. Quite the opposite, a slight prolongation of the graft survival time was observed.     

The Effects of Radiation and Hindlimb Unloading on Rat Bone Marrow Progenitor Cells

Bone marrow cells of mesenchymal origin play an important role in adaptation of physiological systems to space flight. Hematopoiesis, immunity, and homeostasis of bone tissue depend on their functional activity. An investigation that was carried out in the framework of the Bion and Bion-M programs showed a decrease of the number of rat bone marrow hematopoietic progenitors and the inhibition of lympho- and erythropoiesis when the granulocyte-macrophage linage was activated. A negative influence on nonhematopoietic bone marrow cells was also revealed. The pathogenetic influence of radiation and microgravity on the bone marrow progenitor cells has remained unclear so far. The goal of this research was to study the effect of a 30-day unloading and 6 days of γ-irradiation on rat bone marrow progenitor cells. The study was conducted on male rats of four groups: vivarium control (VC), hindlimb unloading (HU), irradiation (IR), and combined action (HU + IR). The following parameters have been examined: the number of bone marrow mononuclear cells, proliferative activity of marrow mononuclear cells, immunophenotype, number of hematopoietic CFU and CFU-f, and differentiation potency of hematopoietic and stromal bone marrow precursors. It was found that the cellularity and proliferation activity of rat bone marrow cells did not change under simulation of space flight. The number of CFU-f was decreased. Irradiation was accompanied by an increase in the hematopoietic cell share among total bone marrow mononuclear cells, while their activity was attenuated. The osteopotential of the stromal precursors was unchanged. Adipogenic differentiation was stimulated with irradiation. The functional activity of bone marrow progenitor cells was restored after 2 weeks of recovery. Thus, 30-day simulation of space flight factors negatively affected the morphofunctional properties of rat bone marrow progenitor cells. These effects were reversible upon 2 weeks of recovery.     

The loss of transportable plutonium deposits from the macrophages of the rat femoral bone marrow

Conclusion The results showed that plutonium may be retained in bone marrow macrophages for a considerable time. Consequently, plutonium deposits in these cells may substantially irradiate components of the surrounding bone marrow and cells on bone surfaces. In red bone marrow these include the radiation sensitive cells which give rise to leukaemia. If follows that bone marrow deposits of plutonium resulting from the turnover of contaminated bone are likely to be important in radiation protection dosimetry. The period of plutonium retention in the bone marrow was found to exceed that in the liver.In addition to the above the results of this study suggest that the autoradiographic methods used to measure the plutonium content of the bone marrow are likely to be suitable for studying those factors which may affect the rate of loss of alpha-emitters from this tissue. These factors include the iron status, sex, and age of the animal and effects of drugs and radiation on the cells.     

Injections of leptin into rat ventromedial hypothalamus increase adipocyte apoptosis in peripheral fat and in bone marrow

The accumulation of fat cells (adipocytes) in bone marrow is now thought to be a factor contributing to age-related bone loss. Women with osteoporosis have higher numbers of marrow adipocytes than women with healthy bone, and bone formation rate is inversely correlated with adipocyte number in bone tissue biopsies from both men and women. Adipogenic differentiation of bone marrow stromal cells increases with age, but the factors regulating populations of mature adipocytes are not well understood. Leptin is thought to regulate adipose tissue mass via its receptors in the ventromedial hypothalamus (VMH). We have therefore tested the hypothesis that stimulation of leptin receptors in the VMH regulates adipocyte number in bone marrow. Results indicate that unilateral twice-daily injections of leptin into the rat VMH for only 4 or 5 days cause a significant reduction in the number of adipocytes in peripheral fat pads and bone marrow and indeed eliminate adipocytes almost entirely from bone marrow of the proximal tibia. Osteoblast surface is not affected with leptin treatment. Apoptosis assays performed on bone marrow samples from control and treated rats have revealed a significant increase in protein concentration of the apoptosis marker caspase-3 with leptin treatment. We conclude that stimulation of leptin receptors in the VMH significantly decreases the adipocyte population in bone marrow, primarily through apoptosis of marrow adipocytes. Elimination of marrow adipocytes via this central pathway may represent a useful strategy for the treatment and prevention of osteoporosis.     

Clonogenic stromal cell count in the bone marrow of mice

The number of fibroblast colonies in bone marrow cultures depends on FCFC concentration in explanted cells and FCFC cloning efficiency. For mouse bone marrow the efficiency of fibroblast colony formation increases in the presence of the feeder (irradiated bone marrow of spleen cells). Colony-stimulating feeder activity does not depend on the presence of phagocytic and stromal cells in the feeder cell population. Trypsinization of the bone marrow leads to the release of additional FCFC and the increase of their concentration in bone marrow cell suspensions.     

The stromal colony-forming cell (CFUf) count in the bone marrow of mice and the clonal nature of the fibroblast colonies they form

The clonal nature of FCFC-derived stromal colonies was tested by chromosomal analysis in mixed cultures of CBA and CBAT6T6 bone marrow cells depleted of macrophages and myeloid cells. Inoculation of the bone marrow cell suspensions in flasks coated with poly-l-lysine has revealed practically no stromal aggregates among the explanted cells. The coincidence of karyotypes within the stromal colonies in the mixed cultures proved that the FCFC-derived colonies were cell clones. It was shown by indirect immunofluorescence with antibodies to type 1 collagen that the mouse bone marrow FCFC-derived colonies consisted of stromal fibroblasts. The cloning efficiency of the bone marrow FCFS depends on the explantation density of cells; a stable colony-forming efficiency could be reached only in the presence of feeder cells (irradiated bone marrow). In the bone marrow cells suspensions obtained by trypsinization the amount of FCFC is markedly higher than in the suspensions of mechanically disaggregated bone marrow cells.     

Greater efficacy of alfacalcidol in the red than in the yellow marrow skeletal sites in adult female rats

The present study compared the bone anabolic effects of graded doses of alfacalcidol in proximal femurs (hematopoietic, red marrow skeletal site) and distal tibiae (fatty, yellow marrow skeletal site). One group of 8.5-month-old female Sprague-Dawley rats were killed at baseline and 4 groups were treated 5 days on/2 days off/week for 12 weeks with 0, 0.025, 0.05 and 0.1 microg alfacalcidol/kg by oral gavage. The proximal femur, bone site with hematopoietic marrow, as well as the distal tibia bone site with fatty marrow, were processed undecalcified for quantitative bone histomorphometry. In the red marrow site of the proximal femoral metaphysis (PFM), 0.1 microg alfacalcidol/kg induced increased cancellous bone mass, improved architecture (decreased trabecular separation, increased connectivity), and stimulated local bone formation of bone 'boutons' (localized bone formation) on trabecular surfaces. There was an imbalance in bone resorption and formation, in which the magnitude of depressed bone resorption greater than depressed bone formation resulted in a positive bone balance. In addition, bone 'bouton' formation contributed to an increase in bone mass. In contrast, the yellow marrow site of the distal tibial metaphysis (DTM), the 0.1 microg alfacalcidol/kg dose induced a non-significant increased cancellous bone mass. The treatment decreased bone resorption equal to the magnitude of decreased bone formation. No bone 'bouton' formation was observed. These findings indicate that the highest dose of 0.1 microg alfacalcidol/kg for 12 weeks increased bone mass (anabolic effect) at the skeletal site with hematopoietic marrow of the proximal femoral metaphysis, but the increased bone mass was greatly attenuated at the fatty marrow site of the distal tibial metaphysis. In addition, the magnitude of the bone gain induced by alfacalcidol treatment in red marrow cancellous bone sites of the proximal femoral metaphysis was half that of the lumbar vertebral body. The latter data were from a previous report from the same animal and protocol. These findings indicated that alfacalcidol as an osteoporosis therapy is less efficacious as a positive bone balance agent that increased trabecular bone mass in a non-vertebral skeletal site where bone marrow is less hematopoietic.     

Conservation of bone marrow CFUc in different phases of the cell cycle during cryopreservation

The effect of low temperature (-196 degrees C) preservation on the recovery of colon-forming units (CFUs) of bone marrow at different phases of the cell cycle before cryopreservation is dealt with. The intact bone marrow "enriched" with CFUs in S phase of the cell cycle and the bone marrow without colony-forming units in S phase were exposed to cryopreservation. After cryopreservation of the bone marrow enriched with CFUs in S phase and th bone marrow without colony-forming units in S phase the number of CFUs decreases by the same value as in the cryopreserved bone marrow obtained from intact mice.     

TLR4在四氯化碳诱导的肝硬化大鼠骨髓血窦内皮细胞的表达

目的：检测Toll样受体4（TLR4）在四氯化碳诱导的肝硬化大鼠骨髓血窦内皮细胞的表达,为进一步研究肝硬化时骨髓损伤的发生机制提供实验依据。方法：选择Wistar大鼠给予腹腔注射CCl4,一周两次,建立肝硬化大鼠模型。分别于建模8周和12周检测大鼠血浆内毒素的水平,免疫组化检测大鼠骨髓血窦内皮细胞上TLR4的表达情况,RT-PCR测定骨髓组织中TLR4mRNA的表达,分析TLR4的表达与内毒素血症间的关系。结果：给予CCl4 8周和12周时,对照组大鼠血浆内毒素水平分别为（0．216±0．024）Eu／ml和（0．133±0．022）Eu／ml,模型组大鼠血浆内毒素水平分别为（0．626±0．021）Eu／ml和（0．725±0．031）Eu／ml,分别较对照组显著升高,差异均有统计学意义（P〈0．001）;骨髓血窦内皮细胞TLR4蛋白表达及骨髓组织中TLR4mRNA的表达均显著高于对照组,差异均有统计学意义（P〈0．05）。大鼠骨髓TLR4蛋白和mRNA表达与血浆内毒素水平均呈显著正相关（r=0．841,0．803,P均〈0．001）。结论：CCl4诱导的肝硬化大鼠骨髓血窦内皮细胞TLR4表达升高,并伴随大鼠内毒素血症的发生,提示肝硬化时肠源性内毒素血症可能参与了骨髓的造血功能的损害和病变。     

TLR4 在四氯化碳诱导的肝硬化大鼠骨髓血窦内皮细胞的表达

目的：检测Toll样受体4(TLR4)在四氯化碳诱导的肝硬化大鼠骨髓血窦内皮细胞的表达,为进一步研究肝硬化时骨髓损伤 的发生机制提供实验依据。方法：选择Wistar大鼠给予腹腔注射CCl4,一周两次,建立肝硬化大鼠模型。分别于建模8 周和12 周 检测大鼠血浆内毒素的水平,免疫组化检测大鼠骨髓血窦内皮细胞上TLR4 的表达情况,RT-PCR 测定骨髓组织中TLR4 mRNA 的表达,分析TLR4 的表达与内毒素血症间的关系。结果：给予CCl4 8 周和12 周时,对照组大鼠血浆内毒素水平分别为(0.216± 0.024) Eu/ml 和(0.133± 0.022) Eu/ml,模型组大鼠血浆内毒素水平分别为(0.626± 0.021) Eu/ml 和(0.725± 0.031) Eu/ml,分别较对 照组显著升高,差异均有统计学意义(P<0.001);骨髓血窦内皮细胞TLR4蛋白表达及骨髓组织中TLR4 mRNA的表达均显著高于 对照组,差异均有统计学意义(P<0.05)。大鼠骨髓TLR4 蛋白和mRNA表达与血浆内毒素水平均呈显著正相关（r=0.841,0.803,P 均<0.001）。结论：CCl4 诱导的肝硬化大鼠骨髓血窦内皮细胞TLR4 表达升高,并伴随大鼠内毒素血症的发生,提示肝硬化时肠源 性内毒素血症可能参与了骨髓的造血功能的损害和病变。     

Differentiating Functional Roles of Gene Expression from Immune and Non-immune Cells in Mouse Colitis by Bone Marrow Transplantation

To understand the role of a gene in the development of colitis, we compared the responses of wild-type mice and gene-of-interest deficient knockout mice to colitis. If the gene-of-interest is expressed in both bone marrow derived cells and non-bone marrow derived cells of the host; however, it is possible to differentiate the role of a gene of interest in bone marrow derived cells and non- bone marrow derived cells by bone marrow transplantation technique. To change the bone marrow derived cell genotype of mice, the original bone marrow of recipient mice were destroyed by irradiation and then replaced by new donor bone marrow of different genotype. When wild-type mice donor bone marrow was transplanted to knockout mice, we could generate knockout mice with wild-type gene expression in bone marrow derived cells. Alternatively, when knockout mice donor bone marrow was transplanted to wild-type recipient mice, wild-type mice without gene-of-interest expressing from bone marrow derived cells were produced. However, bone marrow transplantation may not be 100% complete. Therefore, we utilized cluster of differentiation (CD) molecules (CD45.1 and CD45.2) as markers of donor and recipient cells to track the proportion of donor bone marrow derived cells in recipient mice and success of bone marrow transplantation. Wild-type mice with CD45.1 genotype and knockout mice with CD45.2 genotype were used. After irradiation of recipient mice, the donor bone marrow cells of different genotypes were infused into the recipient mice. When the new bone marrow regenerated to take over its immunity, the mice were challenged by chemical agent (dextran sodium sulfate, DSS 5%) to induce colitis. Here we also showed the method to induce colitis in mice and evaluate the role of the gene of interest expressed from bone-marrow derived cells. If the gene-of-interest from the bone derived cells plays an important role in the development of the disease (such as colitis), the phenotype of the recipient mice with bone marrow transplantation can be significantly altered. At the end of colitis experiments, the bone marrow derived cells in blood and bone marrow were labeled with antibodies against CD45.1 and CD45.2 and their quantitative ratio of existence could be used to evaluate the success of bone marrow transplantation by flow cytometry. Successful bone marrow transplantation should show a vast majority of donor genotype (in term of CD molecule marker) over recipient genotype in both the bone marrow and blood of recipient mice.     

Natural killer cells, bone, and the bone marrow: studies in estrogen-treated mice and in congenitally osteopetrotic (mi/mi) mice.

Mice lose natural killer cells after 6 weeks of treatment with 17 beta-estradiol. We here demonstrate that the same protocol leads to loss of genetic resistance to bone marrow transplantation and to significant osteoproliferation with loss of bone marrow. We also show that mice with reduced marrow because of congenital osteopetrosis are deficient in natural killing. These findings are consistent with previous evidence that natural killing and genetic resistance to bone marrow transplantation are dependent upon the marrow. Temporal studies of bone histology and radiology during and after treatment with estrogen reveal that alterations in natural killing proceed more rapidly than changes in bone marrow volume. These studies also demonstrate that estrogens induce osteoproliferation only at endosteal surfaces that are adjacent to hematopoietic marrow. From these observations, we conclude that estrogens do not reduce natural killer cells simply by reducing the volume of bone marrow. Estrogens may instead have an effect on bone marrow. Estrogens may instead have an effect on bone marrow cells that leads both to osteoproliferation and to a deficiency of marrow-dependent cells.     

骨髓淋巴细胞的分离

目的:探讨骨髓淋巴细胞的分离方法。方法:对18例疑似血液病患者,分别抽取骨髓0.2ml,参照淋巴细胞分离步骤来分离骨髓淋巴细胞,并且对骨髓细胞进行活力检测,分别观察骨髓淋巴细胞的形态及计算骨髓淋巴细胞的活力。结果:骨髓淋巴细胞外形呈圆形或椭圆形、边缘整齐,胞浆量很少,似裸核,胞质如可见,呈淡蓝色,一般无颗粒;胞核圆形或有小切迹,染色质聚集成大块状,结构紧密,结块边缘不清楚,染紫红色;镜下观察发现骨髓淋巴细胞的活力>95%。结论:Ficoll分离液可以对骨髓淋巴细胞进行分离,将为成熟淋巴细胞的研究以及其在炎症性疾病中的发病机制及治疗提供一个新的思路。     

Splenocytes Seed Bone Marrow of Myeloablated Mice: Implication for Atherosclerosis

Extramedullary hematopoiesis has been shown to contribute to the pathogenesis of a variety of diseases including cardiovascular diseases. In this process, the spleen is seeded with mobilized bone marrow cells that augment its hematopoietic ability. It is unclear whether these immigrant cells that are produced/reprogrammed in spleen are similar or different from those found in the bone marrow. To begin to understand this, we investigated the relative potency of adult splenocytes per se to repopulate bone marrow of lethally-irradiated mice and its functional consequences in atherosclerosis. The splenocytes were harvested from GFP donor mice and transplanted into myeloablated wild type recipient mice without the inclusion of any bone marrow helper cells. We found that adult splenocytes repopulated bone marrow of myeloablated mice and the transplanted cells differentiated into a full repertoire of myeloid cell lineages. The level of monocytes/macrophages in the bone marrow of recipient mice was dependent on the cell origin, i.e., the donor splenocytes gave rise to significantly more monocytes/macrophages than the donor bone marrow cells. This occurred despite a significantly lower number of hematopoietic stem cells being present in the donor splenocytes when compared with donor bone marrow cells. Atherosclerosis studies revealed that donor splenocytes displayed a similar level of atherogenic and atheroprotective activities to those of donor bone marrow cells. Cell culture studies showed that the phenotype of macrophages derived from spleen is different from those of bone marrow. Together, these results demonstrate that splenocytes can seed bone marrow of myeloablated mice and modulate atherosclerosis. In addition, our study shows the potential of splenocytes for therapeutic interventions in inflammatory disease.     

Increased bone mass is a part of the generalized lymphoproliferative disorder phenotype in the mouse

We investigated the bone phenotype of mice with generalized lymphoproliferative disorder (gld) due to a defect in the Fas ligand-mediated apoptotic pathway. C57BL/6-gld mice had greater whole body bone mineral density and greater trabecular bone volume than their wild-type controls. gld mice lost 5-fold less trabecular bone and had less osteoclasts on bone surfaces after ovariectomy-induced bone resorption. They also formed more bone in a model of osteogenic regeneration after bone marrow ablation, had less osteoclasts on bone surfaces and less apoptotic osteoblasts. gld and wild-type mice had similar numbers of osteoclasts in bone marrow cultures, but marrow stromal fibroblasts from gld mice formed more alkaline phosphatase-positive colonies. Bone diaphyseal shafts and bone marrow stromal fibroblasts produced more osteoprotegerin mRNA and protein than wild-type mice. These findings provide evidence that the disturbance of the bone system is a part of generalized lymphoproliferative syndrome and indicates the possible role of osteoprotegerin as a regulatory link between the bone and immune system.     

Constitutive expression of IL-6-LIKE cytokines in normal bone marrow: implications for pathophysiology of myeloma

Myeloma is a neoplasm thought to "home" to bone marrow. However, evidence for bone-marrow-specific receptors or adhesion molecules expressed on myeloma cells is scanty. Initial myeloma expansion is thought to be due to IL-6 and/or related cytokines. Previous determinations of cytokine expression in bone marrow were performed on bone marrow stromal lines; these findings may not reflect the constitutive pattern of expression in situ. Intracytoplasmic staining for IL-6-like cytokines revealed constitutive expression of some factors in the bone marrow of normal mice, but not spleens. Spleens of myeloma-transplanted SCID mice expressed IL-6-like cytokines, indicative of induction of expression by myeloma. Some cytokines expressed in bone marrow induced myeloma proliferation in the presence of dexamethasone, demonstrating dependence of the myeloma on these cytokines. Our data imply that, rather than "homing" to bone marrow, myeloma cells proliferated within marrow cavities more than in other organs because of growth factors constitutively expressed by bone marrow cells. As myeloma progressed, we observed the induction of growth factor expression in spleen cells. Furthermore, because cytokines other than IL-6 may induce myeloma cell proliferation, therapy aimed at neutralizing IL-6 may not be the most effective method to treat this disease. These findings have implications for both the pathophysiology and therapy of multiple myeloma.