Mouse model for the equilibration interaction between the host immune system and human T-cell leukemia virus type 1 gene expression

To study the involvement of immune responses against Tax of human T-cell leukemia virus type 1 (HTLV-1) in the growth of and gene suppression in Tax-expressing tumor cells in vivo, we established a model system involving C57BL/6J mice and a syngeneic lymphoma cell line, EL4. When mice were immunized by DNA-based immunization with Tax expression plasmids, solid tumor formation upon subcutaneous inoculation of EL4 cells expressing green fluorescent protein-fused Tax (Gax) under the control of the HTLV-1 enhancer was strongly inhibited, and in vitro analysis showed that DNA immunization elicited cytotoxic T-lymphocyte (CTL) responses but not production of antibodies to Tax protein. Since EL4/Gax cells inoculated into DNA-immunized mice were not completely eradicated but were maintained as small solid tumors for a long period, there appeared to be a certain equilibrium between CTL activity and the growth of Gax-expressing cells. With such a balance, expression of the Gax gene in EL4/Gax cells was strongly suppressed. These results suggested that gene expression under the control of the HTLV-1 long terminal repeat and Tax is silenced in vivo, resulting in an equilibrium between viral expression and the host immune system. Such a balance would represent a status of persistent infection by HTLV-1 in virus-infected individuals during the latency period.     

In vivo generation of lymphokine-activated killer cells by sensitization with interleukin 2-producing syngeneic T-lymphoma cells

Culture of C57BL/6 mouse spleen cells with syngeneic EL4 lymphoma cells resulted in no induction of killer cells reactive against EL4 cells. However, in vitro sensitization of C57BL/6 mouse spleen cells with interleukin 2 (IL-2)-producing EL4 lymphoma cells caused the generation of lymphokine-activated killer (LAK) cells, which lyse a variety of tumor cells. Consistent with an in vitro system, we demonstrate that Thy 1.2+, Ly2+, asialo GM1+ LAK cells were successfully induced by in vivo immunization with syngeneic IL-2-producing EL4 lymphoma cells.     

Wound healing and angiogenic properties of supernatants from Lactobacillus cultures

Extracts or supernatants from cultures of Lactobacilli are used for their medicinal effects, including wound healing and immune system stimulating activity. We have studied the in vivo and in vitro effects of supernatants from bacterial cultures of two strains of Lactobacillus (LS) on tissue repair and angiogenesis. Subcutaneous injection of LS into rodent ears led to proliferation of blood vessels that also exhibited strong immunostaining for Flk-1 receptor. Some inflammatory cells were scattered among the blood vessels. The continuous influx of polymorphonuclear leukocytes (PMNs) and macrophages into transcutaneous wounds in mice treated with LS resulted in prolonged inflammatory phase of wound healing and delayed wound closure, including reepithelialization. Subcutaneous injection of Matrigel impregnated with LS into the abdominal wall led to rapid and transient influx of PMNs in the vicinity of the gel. LS stimulated the proliferation of murine macrophage J774.A1 cell line and porcine lymphocytes but not that of murine fibroblast AKR-2B cells. LS also induced production of TNF-alpha by J774.A1 cells and by porcine kidney epithelial LLC-PK1 cells. LS did not appear to have an effect on collagen production. In conclusion, our study demonstrates the potential of LS to function as a stimulator of the inflammatory stage of tissue repair, TNF-alpha production, and of angiogenesis.     

Absence of CXCL10 Aggravates Herpes Stromal Keratitis with Reduced Primary Neutrophil Influx in Mice

Herpes simplex virus 1 (HSV-1) replication initiates inflammation and angiogenesis responses in the cornea to result in herpetic stromal keratitis (HSK), which is a leading cause of infection-induced vision impairment. Chemokines are secreted to modulate HSK by recruiting leukocytes, which affect virus growth, and by influencing angiogenesis. The present study used a murine infection model to investigate the significance of the chemokine CXC chemokine ligand 10 (CXCL10; gamma interferon-inducible protein 10 [IP-10]) in HSK. Here, we show that HSV-1 infection of the cornea induced CXCL10 protein expression in epithelial cells. The corneas of mice with a targeted disruption of the gene encoding CXCL10 displayed decreases in levels of neutrophil-attracting cytokine (interleukin-6), primary neutrophil influx, and viral clearance 2 or 3 days postinfection. Subsequently, absence of CXCL10 aggravated HSK with elevated levels of interleukin-6, chemokines for CD4⁺ T cells and/or neutrophils (macrophage inflammatory protein-1α and macrophage inflammatory protein-2), angiogenic factor (vascular endothelial growth factor A), and secondary neutrophil influx, as well as infiltration of CD4⁺ T cells to exacerbate opacity and angiogenesis in the cornea at 14 and up to 28 days postinfection. Our results collectively show that endogenous CXCL10 contributes to recruit the primary neutrophil influx and to affect the expression of cytokines, chemokines, and angiogenic factors as well as to reduce the viral titer and HSK severity.     

Neutralization of the CXC chemokine, macrophage inflammatory protein-2, attenuates bleomycin-induced pulmonary fibrosis

Few studies have addressed the importance of vascular remodeling in the lung during the development of bleomycin-induced pulmonary fibrosis. For fibroplasia and deposition of extracellular matrix to occur, there must be a geometric increase in neovascularization. We hypothesized that net angiogenesis during the pathogenesis of fibroplasia and deposition of extracellular matrix during bleomycin-induced pulmonary fibrosis are dependent in part upon an overexpression of the angiogenic CXC chemokine, macrophage inflammatory protein-2 (MIP-2). To test this hypothesis, we measured MIP-2 by specific ELISA in whole lung homogenates in either bleomycin-treated or control CBA/J mice and correlated these levels with lung hydroxyproline. We found that lung tissue from mice treated with bleomycin, compared with that from saline-treated controls, demonstrated a significant increase in the presence of MIP-2 that was correlated to a greater angiogenic response and total lung hydroxyproline content. Neutralizing anti-MIP-2 Abs inhibited the angiogenic activity of day 16 bleomycin-treated lung specimens using an in vivo angiogenesis bioassay. Furthermore, when MIP-2 was depleted in vivo by passive immunization, bleomycin-induced pulmonary fibrosis was significantly reduced without a change in the presence of pulmonary neutrophils, fibroblast proliferation, or collagen gene expression. This was also paralleled by a reduction in angiogenesis. These results demonstrate that the angiogenic CXC chemokine, MIP-2, is an important factor that regulates angiogenesis/fibrosis in pulmonary fibrosis.     

An in vitro model of fibroplasia: simultaneous quantification of fibroblast proliferation, migration, and collagen synthesis

Previous studies of fibroblast proliferation, migration, and collagen synthesis have been limited in their ability to define the interrelationship among these events in response to various inflammatory mediators. We have now defined an in vitro tissue culture model for the synchronous quantification of these parameters of fibroplasia. Biopsies (2 mm) of chicken flexor tendons are embedded in a fibrin matrix and exposed to various factors for 5 days in tissue culture. The availability of the fibrin matrix surrounding the tendon biopsy satisfies the need for a solid support medium for fibroblast migration. Multiple measurements of tendon fibroblast proliferation, migration into the fibrin matrix, and relative collagen synthesis are then made on these preparations. Fetal calf serum stimulated tendon fibroblast proliferation and migration in a dose responsive fashion, whereas the selective expression of collagen synthesis was decreased. Platelet lysate stimulated fibroblast proliferation at low concentration, but migration only at high concentration and was without effect on relative collagen synthesis. This model now provides a means of more clearly defining the influence of various inflammatory factors on the events of fibroplasia.     

In vivo cytotoxic responses induced by allogeneic normal and neoplastic cells in mice: relative lack of immunogenicity of B16 melanoma cells

It has been previously reported from this laboratory that the C57BL/6 melanoma B16 will grow in allogeneic mice provided that donor-derived passenger leukocytes are first removed by in vitro passage of the tumor cells. In this paper we report that allogeneic and syngeneic mice support similar survival of [125I]iododeoxyuridine-labeled B16 cells (125I-B16 cells) as indicated by whole-body retention of 125I. B16 failed to induce the early cytotoxic response which was induced by semiallogeneic peritoneal cells (PC) and by two other allogeneic tumors (EL4 lymphoma and MC-2 sarcoma). They were nevertheless rapidly destroyed by the response induced by PC or EL4. B16 did show some immunogenicity as indicated by regression of some primary B16 tumors (45% ip and the majority of footpad tumors) and by the slow cytotoxic response to secondary 125I-B16 challenge following preimmunization with live or irradiated B16 cells. An equivalent response was induced by preimmunization with a 100-fold lower dose of PC. These findings are discussed in relation to the requirement for inductive stimuli, in addition to antigen, for the stimulation of in vivo cytotoxic responses.     

H-2 antigen expression: Loss in vitro,restoration in vivo,and correlation with cell-mediated cytotoxicity in a mouse lymphoma cell line

The susceptibility to cell-mediated cytolysis of cells of the recently developed C57BL/Ka(H-2 ^b ) lymphoma cell line, BL/VL₃, was investigated in allogeneic assays with thymus-dependent lymphocytes (T cells). Compared to EL4, the widely used C57BL/6(H-2 ^b ) lymphoma cell line, BL/VL₃ cells were found to be insensitive to T-cell-mediated lysis as detected by the use of⁵¹Crrelease methods. When used as immunogens in alloreactive combinations with BALB/c(H-2 ^d ) splenocytes as responder cells, BL/VL₃ cells failed to elicit sensitization. Serological tests showed that this cell line had profoundly reduced levels of H-2^b antigens on its surface. When BL/VL₃ cells were reinjected into C57BL/Ka and BALB/c mice, full recovery of H-2^b antigen expression at the cell surface was observed in both syngeneic and allogeneic hosts after only 11 days of in vivo growth. Concomitantly, they acquired the ability to induce cytotoxic responses in allogeneic T cells and became susceptible to their lytic activity. The expression of H-2 antigens on the surface of BL/VL₃ cells is a reversibly modulated function that depends on in vivo growth conditions and is lost in vitro in the absence of immunoselective pressure.     

Synergistic anti-suppressor effect of mini cells prepared from Salmonella typhimurium and mitomycin C in EL 4-bearing mice

Summary The subcutaneous growth of EL4 cells was significantly accelerated when they were injected together with spleen cells collected from mice which had received EL4 cells SC 14 days previously, and all mice died within 18 days after receiving this mixture; 80% of mice which received a mixture of EL4 and spleen cells collected immediately after EL4 graft survived over 40 days. Spleen cells collected 14 days after EL4 graft suppressed the blastogenic responses of normal spleen lymphocytes to concanavalin A, pokeweed mitogen, and lipopolysaccharide of Escherichia coli in a mixed culture system.Acceleration of tumor growth was retarded when EL4 cells were injected together with spleen cells from EL4-bearing mice treated with both Salmonella typhimurium mini-cells and mitomycin C, and 60% of mice survived over 40 days. Blastogenic responses of normal spleen lymphocytes mixed with spleen cells from EL4-bearing mice treated with both mini-cells and mitomcycin C were restored almost to control levels. The results suggest that combination treatment with mini-cells and mitomycin C synergistically inhibits the induction of suppressor cells in EL4-bearing mice.     

In vitro cytotoxicity of peritoneal macrophages activated with Mycobacterium smegmatis

Incorporation of 3H-TdR into EL4 leukemic cells in vitro was inhibited by peritoneal exudate cells (PEC) harvested from syngeneic C57BL/6J mice given an intraperitoneal (i.p.) injection of 1x10(7) viable Mycobacterium smegmatis ATCC 607 (Smeg) 4 days before. This phenomenon was also observed in the following five systems of PEC from animals and syngeneic tumor cells: C57BL/6J mice and B16 melanoma; DBA/2 mice and P815 mastocytoma; SWM/Ms mice and K5 fibrosarcoma; BALB/c, nu/nu mice and KKN-1 fibrosarcoma; and strain 2 guinea pigs and line-10 hepatoma. The in vitro cytotoxicity of the PEC activated by viable Smeg was much higher than those activated by dead-Smeg, viable BCG or proteose peptone. The activity of the adherent fraction of the PEC was stronger than that of the nonadherent one, and not influenced by either anti-theta or anti-mouse lymphocyte rabbit sera. The PEC induced with Smeg 4 days before contained a large population of mononuclear cells (88.9%) and a significant level of polymorphonuclear cells (PMN) (3.2%), and showed a much higher cytotoxicity than the PEC induced with Smeg 3 hr before, which contained a much larger population of PMN (71.9%), suggesting that PMN were not the effector cells in this system. In vitro and in vivo treatment with macrophage-inhibitors such as carrageenan, trypan blue and cytochalacin B, reduced the activity of the PEC. All of these facts suggested macrophages as the effector. Viable macrophages were required for the growth inhibition of EL4 in vitro: gamma-ray irradiated or freeze-thawed macrophages were ineffective. Kinetic studies revealed that inhibition of 3H-TdR incorporation into EL4 cells started within 3 hr of incubation together with the activated macrophages at an effector to target (E/T) ratio of 5, and the incorporation decreased gradually with the lapse of incubation time. On the other hand, 51Cr release from labelled EL4 was undetected when the E/T ratio was 5 but detected at on E/T of 10 or more. Even at the higher E/T ratio, at least 10 hr were needed until the release of 51Cr, suggesting that the activated macrophages produced growth inhibition of tumor cells followed by cell destruction.     

Formation of specific antitumor cytotoxic T-lymphocytes in monoculture]

A new model for the generation of specific antitumor cytotoxic T-lymphocytes (CTL) was proposed. In contrast to other models, it allows to generate effector CTL without immunization in vitro. C57BL/10 mice or/and C57BL/6 mice were immunized by injection with gamma-irradiated syngeneic tumor cells into the footpads. For estimation of cytotoxic activity, chromium-51 release assay was used. It has been shown that effector CTL were absent in the lymph nodes in 1-fold as well as 2-fold immunization. Cytotoxic cells have not been found in 1-fold immunization even after maturation of the lymphocytes in monoculture. Specific CTL were detected only after secondary immunization and subsequent cultivation in vitro. Effector cells had Thy1.2+, Lyt2+, L3T4- phenotypes. Presence in vitro of exogenous IL-2 was needed for the generation of CTL against MX-11 sarcoma but not against EL4 lymphoma. We suggest that the release of IL-2 from lymphomas cells could stimulate generation of the effector cells through activation of the endogenous production of IL-2, or due to some other factors.     

Overexpression of Interleukin-1α Suppresses Liver Metastasis of Lymphoma: Implications for Antitumor Effects of CD8+ T-cells

Interleukin (IL)-1 plays a key role in carcinogenesis, tumor progression, and metastasis. Although IL-1 may enhance the expansion of CD8+ T-cells, the pathological contribution of IL-1-activated CD8+ T-cells to tumor metastasis remains unclear. This study used a liver metastasis model of the EL4 T-cell lymphoma cells transplanted into human IL (hIL)-1α conditional transgenic (hIL-1α cTg) mice. Overproduction of hIL-1α suppressed both macroscopic and histological liver metastasis of EL4 T-cell lymphoma. The hIL-1α-induced inflammatory state increased the number of CD8+ T-cells both within and around metastatic tumors. Moreover, larger numbers of CD8+ T-cells showed greater infiltration of liver blood vessels in hIL-1α cTg mice than in control wild-type mice. Terminal deoxynucleotidyl transferase dUTP nick-end labeling staining of liver tissue from hIL-1α cTg mice indicated increased apoptosis of cells in the tumor. Localization of apoptosis cells resembled that of CD8+ T-cells. In addition, cytotoxicity assay showed that CD8+ T-cell counts from tumor-bearing hIL-1α cTg mice correlated with cytotoxicity against EL4. In summary, IL-1α suppresses lymphoma metastasis, and IL-1α-activated CD8+ T-cells may play important roles in inhibiting both tumor metastasis and metastatic tumor growth:     

Self-reactive T cell receptor-reactive CD8+ T cells inhibit T cell lymphoma growth in vivo

Syngenic C57BL/6 mice (H-2(b)) vaccinated with mitomycin C-treated L12R4 T lymphoma cells develop protective immunity toward the MHC class II-negative tumor cells. In the present study, we characterize the nature, mode of function, and specificity of the effector cells in this immunity. These cells are TCR-specific CD8(+) T lymphocytes with effector function in vitro as well as in vivo upon transfer to naive mice. They produce high levels of IFN-gamma and TNF-alpha, but little or no IL-4. By means of TCRbeta-negative variant L12R4 cells, P3.3, and TCR-Vbeta2 cDNA-transfected and TCR-Vbeta2-expressing P3.3 lymphoma cells, we found that a significant part of the effector T cells are specific for the Vbeta12 region. The growth inhibition of L12R4 cells in vitro was inhibited by anti-H-2, anti-K(b), and anti-D(b) mAb. Furthermore, vaccination with Vbeta12 peptide p67-78, which binds to both K(b) and D(b) MHC class I molecules, induces partial protection against L12R4 T lymphoma cells. Thus, self-reactive TCR-Vbeta-specific, K(b)-, or D(b)-restricted CD8(+) T cells mediate inhibition of T cell lymphoma growth in vitro and in vivo.     

Induction of cardiac angiogenesis requires killer cell lectin-like receptor 1 and α4β7 integrin expression by NK cells

Recent findings indicate that NK cells are involved in cardiac repair following myocardial infarction. The aim of this study is to investigate the role NK cells in infarct angiogenesis and cardiac remodeling. In normal C57BL/6 mice, myelomonocytic inflammatory cells invaded infarcted heart within 24 h followed by a lymphoid/NK cell infiltrate by day 6, accompanied by substantial expression of IL-2, TNF-α, and CCL2. In contrast, NOD SCID mice had virtually no lymphoid cells infiltrating the heart and did not upregulate IL-2 levels. In vitro and in vivo, IL-2-activated NK cells promoted TNF-α-stimulated endothelial cell proliferation, enhanced angiogenesis and reduced fibrosis within the infarcted myocardium. Adoptive transfer of IL-2-activated NK cells to NOD SCID mice improved post-myocardial infarction angiogenesis. RNA silencing technology and neutralizing Abs demonstrated that this process involved α4β7 integrin/VCAM-1 and killer cell lectin-like receptor 1/N-cadherin-specific binding. In this study, we show that IL-2-activated NK cells reduce myocardial collagen deposition along with an increase in neovascularization following acute cardiac ischemia through specific interaction with endothelial cells. These data define a potential role of activated NK cells in cardiac angiogenesis and open new perspectives for the treatment of ischemic diseases.     

Resistance to a peritoneal lymphoma graft induced by heat-killed S or R Brucella abortus

Summary Mice were injected either with the rough (R) or smooth (S) strains of killed Brucella abortus, after which, at various times, they were given an i.p. injection of a strain-specific lymphoma (EL4). In parallel, samples of peritoneal exudate cells were taken from the Brucella-injected mice, and their in vitro cytostatic activity against EL4 tumour cells was investigated. Protection against the lymphoma graft lasted up to the 7th day with S and the 20th with R. In contrast, cytostatic activity was more intense and lasted longer with S than with R. The parallelism between in vivo resistance to the lymphoma graft and augmentation of macrophage cytostatic activity was satisfactory with R but not with S. The differential effects of S and R on EL4 lymphoma growth could not be simply explained on the basis of a difference in macrophage activation.     

Cyclophosphamide modifies the induction kinetics but not cell types and cytotoxic mechanisms of antitumor cells elicited with OK-432 plus attenuated tumor cells

Summary The present study was designed to examine whether the antitumor cells induced by treatment with mitomycin-C-treated EL4 cells (EL4_MMC) plus OK-432 plus cyclophosphamide differed from those induced by treatment with EL4_MMC plus OK-432 in terms of their cell types and antitumor mechanisms. Antitumor activity of peritoneal exudate cells (PEC) from mice receiving either treatment was nonspecific, and inhibition of their target cell growth increased for up to 24 h. Macrophage toxin, silica and trypan blue abrogated the activity in vitro and in vivo, respectively. The activity of the PEC was inhibited with inhibitors of the arachidonic acid cascade, such as dexamethasone, 4-bromophenacyl bromide and nordihydroguaiaretic acid but not esculetin, ibuprofen, indomethacin and BW755C.N ^G-monomethyl-l-arginine, a specific competitive inhibitor of thel-arginine-dependent nitric oxide synthesis, also inhibited the activity. These results and morphological observations indicated that antitumor cells in the PEC from mice receiving either treatment were macrophages, and that their activity was closely related to the arachidonic acid cascade and to nitric oxide. Antitumor activity of the PEC spontaneously decayed in vitro and this decay was inhibited by the addition of OK-432 or lipopolysaccharide. On the other hand, cyclophosphamide sustained the appearance of antitumor cells in mice treated with EL4_MMC plus OK-432. Therefore, cyclophosphamide treatment did not modify cell types and cytotoxic mechanisms of antitumor cells elicited with EL4_MMC plus OK-432, but did modify the induction kinetics of such antitumor macrophages.     

EDTA separation and recombination of epithelium and connective tissue of human oral mucosa. Studies of tissue transplants in nude mice

A possible epithelial-mesenchymal interaction in determining epithelial histologic features of human oral mucosa was examined. The study comprised 74 biopsies of normal buccal mucosa and 54 biopsies of normal palatal mucosa. Epithelium was separated from connective tissue by the use of 1 mM ethylenediamine tetraacetate dihydrate. Self-recombined and cross-recombined epithelial and connective tissues and connective tissue sheets alone were transplanted to subcutaneous sites of nude mice. Histologic examination of cross-recombined palatal epithelium/buccal connective tissue transplants showed a change in keratinization pattern but no major change in number of epithelial cell layers as the result of connective tissue influence. Transplanted sheets of connective tissue after growth for 14 days showed that complete separation of biopsies from buccal mucosa had been obtained. However, palatal mucosa had been incompletely separated as evidenced by re-epithelialization of most of the connective tissue transplants. The consequences of the incomplete palatal epithelium-connective tissue separation are discussed.     

An antibody for macrophage migration inhibitory factor suppresses tumour growth and inhibits tumour-associated angiogenesis

To verify the role of macrophage migration inhibitory factor (MIF) in tumourigenesis, we examined the effect of an anti-MIF antibody on tumour growth and angiogenesis. We inoculated murine colon adenocarcinoma cell line colon 26 cells subcutaneously into the flank in BALB/c mice. After nine days, we treated tumour-bearing mice with an anti-rat MIF antibody by intraperitoneal injection on days 9, 11, 13, 15, 17, 19 and 21. We found significant inhibition of tumour growth by this treatment from day 15 to day 22. Next, we implanted a chamber filled with colon 26 cells, which only passes soluble factors, in the subcutaneous fascia of the flank, and treated mice with the anti-rat MIF antibody at days 1, 3 and 5. By histological examination at day 6, angiogenesis within the subcutaneous fascia in contact with the chamber was markedly suppressed. In vitro, we added an anti-human MIF antibody to human umbilical vein endothelial cells (HUVEC) to evaluate its effect on cell growth by measurement of [3H]thymidine incorporation. We observed that the anti-MIF antibody significantly suppressed [3H]thymidine uptake by HUVEC. These results suggest the possibility that MIF is involved in tumourigenesis via promotion of angiogenesis.     

TGF-β1 stimulates cultured human fibroblasts to proliferate and produce tissue-like fibroplasia: A fibronectin matrix-dependent event

During wound repair, fibroblasts accumulate in the injured area until any defect is filled with stratified layers of cells and matrix. Such fibroplasia also occurs in many fibrotic disorders. Transforming growth factor-β (TGF-β), a promotor of granulation tissue in vivo and extracellular matrix production in vitro, is expressed during the active fibroplasia of wound healing and fibroproliferative diseases. Under usual tissue culture conditions, normal fibroblasts grow to confluence and then cease proliferation. In this study, culture conditions with TGF-β1 have been delineated that promote human fibroblasts to grow in stratified layers mimicking in vivo fibroplasia. When medium supplemented with serum, ascorbate, proline, and TGF-β was added thrice weekly to normal human dermal fibroblasts, the cells proliferated and stratified up to 16 cell layers thick within the culture dish, producing a tissue-like fibroplasia. TGF-β stimulated both DNA synthesis as measured by 1H-thymidine uptake and cell proliferation as measured by a Hoechst dye DNA assay in these postconfluent cultures. The stratification was dependent on fibronectin assembly, as demonstrated by anti-fibronectin antibodies which inhibited both basal and TGF-β-stimulated cell proliferation and stratification. Suppression of collagen matrix assembly in cell layers with β-amino-proprionitrile (BAPN) did not inhibit basal or TGF-β stimulated in vitro fibroplasia. BAPN did not interfere with fibronectin matrix assembly as judged by immunofluorescence microscopy. Thus, in concert with serum factors, TGF-β stimulates postconfluent, fibronectin matrix-dependent, fibroblast growth creating a fibroplasia-like tissue in vitro. J Cell Physiol 170:69–80, 1997 © 1997 Wiley-Liss, Inc.     

Mast cell degranulation mediates compound 48/80-induced hyperalgesia in mice

Mast cells mediate allergies, hypersensitivities, host defense, and venom neutralization. An area of recent interest is the contribution of mast cells to inflammatory pain. Here we found that specific, local activation of mast cells produced plantar hyperalgesia in mice. Basic secretagogue compound 48/80 induced plantar mast cell degranulation accompanied by thermal hyperalgesia, tissue edema, and neutrophil influx in the hindpaws of ND4 Swiss mice. Blocking mast cell degranulation, neutrophil extravasation, and histamine signaling abrogated these responses. Compound 48/80 also produced edema, pain, and neutrophil influx in WT C57BL/6 but not in genetically mast cell-deficient C57BL/6-Kit(W-sh)(/)(W-sh) mice. These responses were restored following plantar reconstitution with bone marrow-derived cultured mast cells.