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Biomedical subjects

Y Kanakura

Publications and source records attributed to Y Kanakura.

At least 127 records · Page 7Linked to original sources
PubMed1991

Identification of functionally distinct domains of human granulocyte-macrophage colony-stimulating factor using monoclonal antibodies.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein that is required for the survival, growth, and differentiation of hematopoietic progenitor cells. Although the primary structure of GM-CSF is known from cDNA cloning, the relationship between structure and function of GM-CSF is not fully understood. Fifteen different monoclonal antibodies (MoAbs) to human GM-CSF were generated to map immunologically distinct areas of the molecule. Each of the MoAbs was biotinylated and shown by enzyme-linked immunosorbent assay to bind to recombinant GM-CSF that had been affixed to a solid phase. Each of the 15 unconjugated MoAbs was then used to compete with each biotinylated MoAb for binding to GM-CSF. These cross-blocking studies identified eight distinct epitopes of native GM-CSF. Seven of these epitopes were also present in denatured GM-CSF by Western blotting, and four of the epitopes were at least partially conserved on GM-CSF that was reduced in beta-mercaptoethanol. MoAbs to four of eight epitopes neutralized both recombinant (glycosylated and nonglycosylated) and natural human GM-CSF in a GM colony-forming unit (CFU-GM) assay and blocked GM-CSF-induced activation of neutrophils. For most of the antibodies there was a good correlation between neutralizing activity and the capacity to block binding of 125I-GM-CSF to neutrophils or blasts. Non-neutralizing antibodies to one epitope partially blocked binding of 125I-GM-CSF to neutrophils. None of the MoAbs neutralized interleukin-3, G-CSF, or M-CSF. The locations of seven of the epitopes could be partially mapped with regard to the amino acid structure by determining reactivity to GM-CSF synthetic peptides or to human-mouse chimeric GM-CSFs. The neutralizing antibodies were found to map to amino acids 40-77, 78-94, or 110-127. Thus, these MoAbs are useful to identify functional domains of GM-CSF and in identifying regions that are likely to be involved in receptor interaction.

Amino Acid Sequence↗
PubMed1991

Granulocyte-macrophage colony-stimulating factor and interleukin-3 induce rapid phosphorylation and activation of the proto-oncogene Raf-1 in a human factor-dependent myeloid cell line.

The product of the c-raf-1 proto-oncogene, Raf-1, is a 74,000-dalton cytoplasmic serine/threonine protein kinase that has been implicated as an intermediate in signal transduction mechanisms. In the human factor-dependent myeloid cell line MO7, both granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-3 (IL-3) were found to induce rapid, dose-dependent phosphorylation of Raf-1, which resulted in altered Raf-1 mobility in sodium dodecyl sulfate-polyacrylamide gels. The increase in phosphorylation was due primarily to an increase in phosphoserine, with only a minor component (less than 2%) of phosphotyrosine. PMA (12-phorbol 13-myristic acid) also induced Raf-1 phosphorylation in MO7 cells, but the resulting alteration in electrophoretic mobility was different than that observed after GM-CSF or IL-3. GM-CSF and IL-3 rapidly and transiently increased Raf-1 kinase activity using Histone H1 as a substrate in an immune complex kinase assay in vitro. These results suggest that phosphorylation of Raf-1 could play a role in some aspect of GM-CSF and IL-3 signal transduction.

Cell Line↗
PubMed1991

Phorbol 12-myristate 13-acetate inhibits granulocyte-macrophage colony stimulating factor-induced protein tyrosine phosphorylation in a human factor-dependent hematopoietic cell line.

The human myeloid cell line MO7 requires either granulocyte-macrophage colony stimulating factor (GM-CSF) or interleukin 3 (IL-3) for proliferation. We have previously shown that both GM-CSF and IL-3 transiently induce tyrosine phosphorylation of a number of proteins, including two cytosolic proteins, p93 and p70, which are maximally phosphorylated 5-15 min after addition of growth factor to factor-deprived cells. GM-CSF-induced proliferation of MO7 cells was found to be inhibited by two activators of protein kinase C, phorbol 12-myristate 13-acetate (PMA) and bryostatin-1. PMA did not affect surface expression or affinity of the GM-CSF receptor but significantly inhibited GM-CSF- or IL-3-induced tyrosine phosphorylation of p93 and p70. In contrast, PMA augmented GM-CSF-induced tyrosine phosphorylation of another protein, p42. Pretreatment of cells with sodium orthovanadate to inhibit protein tyrosine phosphatases (PTPase) partially reversed the inhibitory effects of PMA. These results suggest that one aspect of GM-CSF and IL-3 signal transduction, protein tyrosine phosphorylation, can be inhibited by a mechanism which does not involve receptor down-regulation, and may involve either receptor down-regulation, and may involve either inhibition of a receptor-activated tyrosine kinase, activation of a protein tyrosine phosphatase, or both. This mechanism could be important in exerting control of proliferation of some types of hematopoietic cells.

Cell Line↗
PubMed1991

High-affinity interleukin 2 receptors on B cell chronic lymphocytic leukemia cells are induced by phorbol myristate acetate but not by calcium ionophore.

The role of phorbol myristate acetate (PMA: a protein kinase-C (PKC) activator) and calcium ionophore A23187 in the induction mechanism of the interleukin 2 receptor (IL2R) on B-cell chronic lymphocytic leukemia (B-CLL) cells was studied. B-CLL cells from five patients were cultured with PMA or A23187 for 72 h and used for the following experiments. Interleukin 2 (IL2) cross-linking assays showed that PMA induced the expression of IL2R subunits (p55 and p70/75) in all cases examined, but that A23187 induced neither subunit. Radiolabeled IL2 binding assays also demonstrated that PMA induced both high-affinity IL2R (HA-IL2R) and low-affinity IL2R (LA-IL2R) on B-CLL cells, but that A23187 did not. After treatment with PMA, three of five cases did not respond to IL2 even though they expressed HA-IL2R, suggesting impaired signal transduction. No cases responded to IL2 after treatment with A23187. In conclusion, PMA but not A23187 stimulates B-CLL cells to induce the expression of p55 and p70/75, indicating that the PKC pathway plays a more important role than the calcium pathway in the induction of IL2R subunits in B-CLL cells.

Antigens, Surface↗
PubMed1991

Simultaneous administration of granulocyte-macrophage colony-stimulating factor and cytosine arabinoside for the treatment of relapsed acute myeloid leukemia.

The treatment of patients with relapsed or refractory acute myeloid leukemia (AML) with high dose cytosine arabinoside (ara-C) results in short-lived complete response rates of 30-50%. We have previously shown that entry of myeloid leukemic cells into S phase can be accelerated in vitro through the use of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), resulting in enhancement of ara-C-mediated cytotoxicity. In order to evaluate the in vivo biological and clinical effects of this strategy in patients with high risk AML, we treated three patients with either refractory or relapsed disease with a continuous infusion of rhGM-CSF (0.45 micrograms/kg/h aglycoprotein) for 18 h, followed by the institution of high dose ara-C and continuation of rhGM-CSF throughout the 4 day duration of ara-C treatment. Prior to therapy, no patient had detectable levels of circulating rhGM-CSF, and there was no evidence of GM-CSF receptor occupancy in leukemic myeloblasts. After 18 h of rhGM-CSF therapy, all patients had biologically active levels of circulating rhGM-CSF (7.9-12.0 ng/ml), and two patients showed a significant degree of leukemic GM-CSF receptor occupancy without evidence of GM-CSF receptor down-regulation. A significant rise in the S phase fraction of leukemic myeloblasts was observed at 18 h of rhGM-CSF treatment in all three patients (29-56% increment). The toxicity of combined rhGM-CSF/ara-C therapy included pericarditis and cerebellar degeneration in one patient, fever and mild renal dysfunction in two patients, and mild hepatic dysfunction in all three patients. Each patient showed a transient rise in the absolute neutrophil and blast count during rhGM-CSF/ara-C administration, followed by profound, but clinically tolerable, myelosuppression. No patient developed clinical evidence of leukostasis. There was one death related to pericardial tamponade, one death related to refractory disease, and one clinical and cytogenetic remission. These results suggest that exogenously administered rhGM-CSF is capable of rapidly mobilizing leukemic cells into S phase in vivo and theoretically should be useful in overcoming kinetic resistance to ara-C. Clinical trials of this regimen in patients with high risk AML who are not already pharmacologically resistant to ara-C are warranted.

Acute Disease↗
PubMed1991

[Adult T cell leukemia/lymphoma with hyperprolactinemia: successful treatment by OK432 and PSK].

A 48-year-old woman was admitted in September 1987, because of lumbago and galactorrhea. Peripheral blood analysis showed neutrophilia and eosinophilia without abnormal lymphocytes. The antibody to adult T-cell leukemia (ATL) virus-associated antigen was detected and a hyperprolactinemia was observed. The blastogenic responses to PHA, ConA and PWM were lowered. Brain CT and MRI scannings showed no abnormalities in the hypophysis and hypothalamus, but abdomen CT revealed markedly enlarged abdominal lymph nodes. Two months after the administration of OK432 and PSK, the lymph node swellings disappeared and the responses to PHA, ConA and PWM were normalized, but hyperprolactinemia and galactorrhea persisted. After four months of the remission period, the patient developed lymph node swellings again, and was diagnosed from the biopsy specimen of the retroperitoneal lymph node as having malignant lymphoma of diffuse mixed cell type. Southern blot analysis showed a monoclonal integration of HTLV-I proviral DNA. Despite repeated combination chemotherapies, she died of pneumonia in February 1989. Autopsy revealed marked infiltrations of lymphoma cells in the liver, spleen and lungs, but no abnormality accounting for hyperprolactinemia was detected in the suprasellar regions. This case was of interest in that immunotherapy was effective in achieving a remission and in normalizing immuno-parameters in ATLL.

Adjuvants, Immunologic↗
PubMed1990

cdc2 gene expression at the G1 to S transition in human T lymphocytes.

The product of the cdc2 gene, designated p34cdc2, is a serine-threonine protein kinase that controls entry of eukaryotic cells into mitosis. Freshly isolated human T lymphocytes (G0 phase) were found to have very low amounts of p34cdc2 and cdc2 messenger RNA. Expression of cdc2 increased 18 to 24 hours after exposure of T cells to phytohemagglutinin, coincident with the G1 to S transition. Antisense oligodeoxynucleotides could reduce the increase in cdc2 expression and inhibited DNA synthesis, but had no effect on several early and mid-G1 events, including blastogenesis and expression of interleukin-2 receptors, transferrin receptors, c-myb, and c-myc. Induction of cdc2 required prior induction of c-myb and c-myc. These results suggest that cdc2 induction is part of an orderly sequence of events that occurs at the G1 to S transition in T cells.

Base Sequence↗
PubMed1990

Signal transduction of the human granulocyte-macrophage colony-stimulating factor and interleukin-3 receptors involves tyrosine phosphorylation of a common set of cytoplasmic proteins.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) exert multiple effects on the proliferation, differentiation, and function of myeloid lineage cells through their interaction with specific cell-surface receptors. There is a considerable degree of overlap in the biological effects of these two growth factors, but little is known about the mechanisms of postreceptor signal transduction. We have investigated the effects of GM-CSF and IL-3 on protein tyrosine-kinase activity in a human cell line, MO7E, which proliferates in response to either factor. Tyrosine-kinase activity was detected using immunoblotting with a monoclonal antibody (MoAb) specific for phosphotyrosine. GM-CSF and IL-3 were found to induce a nearly identical pattern of protein tyrosine phosphorylation using both one- and two-dimensional gel electrophoresis. Tyrosine phosphorylation of two cytosolic proteins in particular was increased more than 10-fold, a 93-Kd protein (pp93) and a 70-Kd protein (pp70). Tyrosine phosphorylation of pp93 and pp70 was observed within 1 minute, reached a maximum at 5 to 15 minutes, and gradually decreased thereafter. Other proteins of 150, 125, 63, 55, 42, and 36 Kd were also phosphorylated on tyrosine in response to both GM-CSF and IL-3, although to a lesser degree. Tyrosine phosphorylation was dependent on the concentration of GM-CSF over the range of 0.1 to 10 ng/mL and on IL-3 over the range of 1 to 30 ng/mL. Stimulation of MO7E cells with 12-0-tetradecanoyl-phorbol-13-acetate (TPA) or cytokines such as G-CSF, M-CSF, interleukin-1 (IL-1), interleukin-4 (IL-4), interleukin-6 (IL-6), interferon gamma, tumor necrosis factor (TNF), or transforming growth factor-beta (TGF-beta) did not induce tyrosine phosphorylation of pp93 or pp70, suggesting that these two phosphoproteins are specific for GM-CSF-or IL-3-induced activation. The extent and duration of phosphorylation of all the substrates were increased by pretreatment of cells with vanadate, an inhibitor of protein-tyrosine phosphatases. Importantly, culture of MO7E cells with vanadate (up to 10 mumol/L) resulted in a dose-dependent increase in GM-CSF-or IL-3-induced proliferation of up to 1.8-fold. These results suggest that tyrosine phosphorylation may be important for GM-CSF and IL-3 receptor-mediated signal transduction and that cell proliferation may be, at least partially, regulated by a balance between CSF-induced protein-tyrosine kinase activity and protein-tyrosine phosphatase activity.

Antibodies, Monoclonal↗
PubMed1990

Granulocyte-macrophage colony-stimulating factor and other cytokines regulate surface expression of the leukocyte adhesion molecule-1 on human neutrophils, monocytes, and their precursors.

There is increasing evidence that cytokines such as granulocyte-macrophage (GM)-CSF can profoundly affect the adhesion, aggregation, and mobility of neutrophils both in vitro and in vivo. However, the mechanisms whereby these factors might alter the adhesive properties of neutrophils are incompletely understood. A new family of cellular adhesion molecules has recently been identified by cDNA cloning. The members of this family include human leukocyte adhesion molecule-1 (LAM-1), the human endothelial-leukocyte adhesion molecule, and the mouse leukocyte homing receptor for high endothelial venules, MEL-14. LAM-1 is the human homologue of murine MEL-14, and is believed to mediate binding of leukocytes to human high endothelial venules. LAM-1 can be identified by mAb TQ-1, Leu 8, or anti-LAM1.1. The expression and regulation of LAM-1 on granulocytes, monocytes, and their precursors was investigated using flow cytometry and the anti-LAM-1.1 mAb. Neutrophils, eosinophils, monocytes, marrow myeloid cells, granulocyte/macrophage colony-forming unit, and burst-forming unit for erythroid cells were LAM-1+ by flow microfluorimetry. The regulation of LAM-1 expression was tested by treating various cell populations with cytokines or other stimuli for 0-90 min. Exposure of neutrophils, monocytes, and marrow myeloid cells to GM-CSF induced rapid and complete loss of LAM-1 from the cell surface, but had no effect on LAM-1 expression by lymphocytes. The loss of LAM-1 was temporally correlated with up-regulation of CD11b (Mo1), an adhesion molecule involved in neutrophil aggregation. Several other factors known to activate neutrophils also caused down-regulation of LAM-1 and up-regulation of CD11b, including TNF, FMLP, and leukotriene B4. Interestingly, granulocyte-CSF and IFN-gamma had minimal effects on neutrophil LAM-1 expression. Similar results were observed on monocytes and myeloid precursor cells. Thus, exposure of neutrophils to GM-CSF results in a profound change in surface expression of adhesion molecules, with coordinated up-regulation of CD11b and down-regulation of LAM-1. These changes in adhesion proteins are likely to alter aggregation and mobility of both mature myeloid cells and their precursors in patients receiving certain types of cytokine therapy.

Antibodies, Monoclonal↗
PubMed1990

The biology of GM-CSF: regulation of production and interaction with its receptor.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a small glycoprotein growth factor which stimulates the production and function of neutrophils, eosinophils and monocytes. GM-CSF can be produced by a wide variety of tissue types, including fibroblasts, endothelial cells, T cells, macrophages, mesothelial cells, epithelial cells and many types of tumor cells. In most of these tissues, inflammatory mediators, such as interleukin 1, interleukin 6, tumor necrosis factor or endotoxin, are potent inducers of GM-CSF gene expression, which occurs at least partly by post-transcriptional stabilization of the GM-CSF mRNA. The biological effects of GM-CSF are mediated through binding to cell surface receptors, which appear to be widely expressed by hematopoietic cells and also by some non-hematopoietic cells, such as endothelial cells. Receptor expression is characterized by low number (20-200/cell) and high affinity (Kd = 20-100 pM). At least two different functional classes of GM-CSF receptor have been identified. The neutrophil GM-CSF receptor exclusively binds GM-CSF, while interleukin 3 competes for binding of GM-CSF to a second class of receptors detected on some leukemic cell lines, such as KG1 and MO-7E. Signal transduction involves activation of a tyrosine kinase and possibly G protein-coupled stimulation of Na+/H+ exchange. The exact relationship of the two receptors needs further clarification.

Animals↗
PubMed1990

Expression and state of phosphorylation of the retinoblastoma susceptibility gene product in cycling and noncycling human hematopoietic cells.

The product of the retinoblastoma susceptibility gene RB1 (Rb) is likely to function as an inhibitor of cell growth. Previous studies have suggested that certain growth-suppressing effects of Rb are exerted in G0/G1 phase and that phosphorylation can inactivate these functions. We tested this hypothesis by examining the expression and state of phosphorylation of Rb in several lineages of primary hematopoietic cells that spontaneously arrest in G0 phase. Resting lymphocytes were found to express only unphosphorylated Rb, but phosphorylation of Rb occurred as the cells entered S phase in response to mitogens. In contrast, although monocytes and granulocytes also expressed high levels of unphosphorylated Rb, these terminally differentiated cells did not phosphorylate Rb, nor could they exit from G1 phase in response to growth factors. Thus, Rb phosphorylation appears linked to the ability of a cell to synthesize DNA. In T and B lymphocytes, Rb protein increased 8-fold after stimulation, while RB1 RNA levels increased 2- to 4-fold. Nuclear run-on assays and measurement of RB1 RNA half-life in T cells suggested that the increased RNA abundance was, at least in part, due to increased RNA stability. By contrast, Rb protein levels did not increase in either monocytes or granulocytes after stimulation, although RB1 RNA levels did increase in monocytes. Thus, there are lineage-specific differences in both the regulation of Rb phosphorylation and RB1 gene expression in lymphoid and myeloid cells.

Cell Cycle↗
PubMed1990

Demonstration of interleukin-1 beta transcripts in acute myeloblastic leukemic cells by in situ hybridization.

The cells from some patients with acute myeloblastic leukemia will secrete autostimulatory cytokines in tissue culture without the addition of stimulators such as phorbol 12-myristate 13-acetate. Production of interleukin-1 beta (IL-1 beta), for example, has been observed in up to 50% of cases. In order to investigate the nature of the cell secreting IL-1 beta in AML, we used an antisense RNA probe to detect specific IL-1 beta transcripts in individual leukemic cells by in situ hybridization. In fresh, uncultured cells, IL-1 beta transcripts were observed in 1-40% of undifferentiated leukemic blast cells in 17 of 19 cases. In situ hybridization was at least as sensitive as Northern blot analysis in detecting IL-1 beta transcripts. No correlation of IL-1 beta transcript expression with FAB classification was observed. Normal blood and bone marrow mononuclear cells did not contain cells expressing IL-1 beta transcripts. These results support the concept that the regulation of cytokine genes in AML cells is aberrant.

Adult↗
PubMed1990

Intraperitoneally injected cultured mast cells suppress recruitment and differentiation of bone marrow-derived mast cell precursors in the peritoneal cavity of W/Wv mice.

Bone marrow-derived mast cell precursors form large mast cell colonies in methylcellulose and are designated as L-CFU-Mast. The effect of differentiated mast cells on recruitment and differentiation of L-CFU-Mast was investigated by using genetically mast cell-deficient WBB6F1-W/Wv mice. Giant granules of C57BL/6-bgJ/bgJ (Chediak-Higashi syndrome) mice were used as a marker to identify the origin of L-CFU-Mast and differentiated mast cells. Practically no L-CFU-Mast are present in the peritoneal cavity of WBB6F1-W/Wv mice. When bone marrow cells of WBB6F1(-)+/+ mice were i.v. injected, the concentration of +/+(-)type L-CFU-Mast increased in the peritoneal cavity of WBB6F1-W/Wv mice and became several times greater than that of nontreated WBB6F1(-)+/+ mice. This increase of L-CFU-Mast was suppressed by a prior i.p. injection of bgJ/bgJ-type cultured mast cells. The differentiation of the +/+(-)type L-CFU-Mast to morphologically identifiable mast cells was also suppressed by the i.p. injection of bgJ/bgJ-type cultured mast cells. The present results suggest that the suppression of recruitment and differentiation of L-CFU-Mast is a physiological function of differentiated mast cells.

Animals↗
PubMed1990

Differences in irradiation susceptibility and turnover between mucosal and connective tissue-type mast cells of mice.

Although precursors of mast cells are derived from the bone marrow, phenotypes of mast cells are influenced by the tissues in which final differentiation occurs. Connective tissue-type mast cells (CTMC) and mucosal mast cells (MMC) are different in morphological, biochemical, immunological, and functional criteria. The purpose of the present study was to obtain information about the differentiation process of MMC. First, we compared changes in irradiation susceptibility in mice during the differentiation process of CTMC and MMC. The decrease in irradiation susceptibility was remarkable in the CTMC differentiation process, but it was moderate in that of MMC. Some morphologically identifiable CTMC in the peritoneal cavity had proliferative potential and were highly radioresistant, whereas such a radioresistant population of MMC was not detectable in the gastric mucosa. Second, we estimated the turnover of CTMC and MMC by determining the proportion of mast cells that were labeled with continuously administered bromodeoxyuridine. The turnover of MMC was significantly faster than that of CTMC. The absence of the radioresistant mast cell population in the gastric mucosa appeared to be related to the short life span of MMC.

Animals↗
PubMed1989

Proliferative potential of degranulated murine peritoneal mast cells.

The fate of mast cells after degranulation was investigated. Purified peritoneal mast cells of WBB6F1-+/+ mice were sensitized with monoclonal anti-dinitrophenol (DNP) IgE antibodies and stimulated with DNP conjugated with human serum albumin. Mast cells were vitally stained with neutral red, and highly degranulated mast cells were identified under a phase-contrast microscope and individually picked up with the micromanipulator. When these highly degranulated mast cells were individually plated in methylcellulose, their potential to produce a cluster or a colony was comparable to that of morphologically intact mast cells. Moreover, when highly degranulated mast cells were injected into the skin of genetically mast cell-deficient WBB6F1-W/Wv mice, the proportion of injection sites at which mast cell clusters appeared was comparable to the value observed when morphologically intact mast cells were injected. The present result indicates that proliferative potential of mast cells is not reduced by their degranulation.

Animals↗
PubMed1989

Acceleration of a murine T-cell leukemia associated with loss of interleukin-3 producing activity.

L-8313 is a murine T-cell leukemia cell line the cells of which constitutively produce interleukin-3 (IL-3). S2-8313 is a unique subline of L-8313 which has lost IL-3 producing activity. Although the growth of S2-8313 cells in the bone marrow is comparable to that of L-8313 cells, the survival time of C3H mice grafted with S2-8313 cells is significantly shorter than that of C3H mice grafted with L-8313 cells. The accelerated death observed in C3H mice bearing S2-8313 cells is attributable to early development of granulocytopenia and thrombocytopenia, which resulted from the loss of the IL-3 producing activity.

Animals↗
PubMed1989

In vitro duplication and in vivo cure of mast-cell deficiency of Sl/Sld mutant mice by cloned 3T3 fibroblasts.

Sl/Sld mutant mice are profoundly deficient in tissue mast cells as a result of a defect in the microenvironment promoting the development of these cells. To facilitate the analysis of the Sl mutation, we attempted to establish an in vitro system in which the in vivo defect of Sl/Sld mice could be reproduced. 3T3 cell lines were established from 17-day-old embryos of Sl/Sld and congenic +/+ genotypes and were cocultured with mast cells obtained in vitro from the bone marrow of +/+ mice. All eight 3T3 cell lines derived from +/+ of T-cell-derived growth factors. By contrast, none of eight 3T3 cell lines from Sl/Sld embryos supported mast cells under similar conditions. The defect in Sl/Sld 3T3 cells was further characterized as a failure to induce the G1-to-S transition in synchronized mast cells upon contact, suggesting that the Sl gene product is indispensable for this activity. When 3T3 cells of +/+ genotype, grown on pieces of cellulose acetate membrane, were transplanted into the peritoneal cavity of Sl/Sld mice, mast cells appeared locally in the transplanted 3T3 cell layers. These results suggested an essential role of fibroblasts in vivo as the tissue microenvironment promoting the development of mast cells and that they are defective in Sl/Sld mice. The present coculture system duplicated mast-cell deficiency of Sl/Sld mice in vitro and should prove useful for analysis of the Sl gene product.

Animals↗