Biomedical subjects

J Hosoi

Publications and source records attributed to J Hosoi.

At least 19 recordsLinked to original sources

PubMed2001

Mitigation of stress-induced suppression of contact hypersensitivity by odorant inhalation.

BACKGROUND: Various skin functions are affected by stress. We have previously shown that odorant inhalation can regulate skin immune reactions. OBJECTIVES: To test the hypothesis that certain odorants can mitigate the effects of stress on skin immune reactions. METHODS: Contact hypersensitivity (CH) reactions were elicited in C57BL/6 mice. Mice were subjected to immobilization stress and were exposed to odorants for 2 days. Epidermal sheets were stained for I-A antigens and analysed by confocal laser scanning microscopy. Serum corticosterone levels were assayed by radioimmunoassay. RESULTS: Exposure of mice to 1,3-dimethoxy-5-methylbenzene (DMMB) had no effect on the intact CH reaction, but it upregulated the reaction suppressed by immobilization stress. Other odorants, including terpinyl acetate and valerian oil, had minor effects on the CH reaction. Suppression of I-A-positive cells was prevented by DMMB inhalation. Valerian oil, but not DMMB, downregulated stress-induced plasma corticosterone levels. CONCLUSIONS: Results suggest that odorant inhalation modulates various physiological pathways, some of which result in regulation of skin function.

Animals↗

PubMed2000

Visual imaging of ion distribution in human epidermis.

The distribution of calcium, magnesium, potassium, sodium, and hydrogen ions in the human epidermis was visualized by blotting to gel containing chemical indicators and the effects of skin barrier disruption were examined. In normal skin, both calcium and magnesium were localized with high concentration in the upper epidermis. EDTA blocked these imaging. The hydrogen ion was also high in the upper epidermis. Sodium did not show obvious gradation in the epidermis. The potassium concentration was the lowest in the upper epidermis. After the barrier disruption, the gradients of calcium, magnesium, and potassium disappeared while the pH gradation was not altered. Observation at a high magnification revealed lower calcium and sodium concentrations in the nucleus. The concentration of magnesium was slightly higher in the nucleus. The novel method of the present study could show the visual image of the ions in frozen tissue without further preparation.

Calcium↗

PubMed2000

Regulation of the cutaneous allergic reaction by humidity.

Humidity is 1 of the environmental factors which regulate skin conditions. Effects of humidity on the cutaneous immune reaction were examined. Contact hypersensitivity to 2,4,6-trinitrochlorobenzene was elicited in C57BL/6 mice. The reaction was greater in mice housed under low humidity conditions (about 10%) for 2 days, at either the induction or elicitation phase, than in mice housed under rather high humidity conditions (80%). After housing under controlled humidity for 2 days, the number of I-A positive cells was 16% higher in the epidermis exposed to the dry condition. The increased population of FITC-positive cells were in regional lymph nodes after painting of FITC during housing under lower humidity. Our study demonstrated that the cutaneous immune reaction is regulated by environmental humidity and suggested 2 possible mechanisms, i.e., increase in Langerhans cells and increased penetration of allergen with low humidity.

Allergens↗

PubMed2000

In this issue

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Journal Article↗

PubMed1999

beta-Endorphin binding and regulation of cytokine expression in Langerhans cells.

Neuropeptides and neurohormones have been shown to be able to regulate cutaneous immune reactions. Binding of beta-endorphin (beta-end) on epidermal Langerhans cells (LC) and effects of beta-end on cytokine expression were examined. Biotinylated beta-end bound to the mouse LC-like cell line, XS52, and the binding was replaced with intact beta-end but not with substance P. beta-End augmented secretion of IL-1 beta and IL-10 from XS52 cells were induced by a combination of LPS and GM-CSF. Induction of TNF alpha was suppressed by beta-end. The regulation of cytokine expression was confirmed in fresh LC by RT-PCR. These results suggest that beta-end is a regulator of skin immune function.

Animals↗

PubMed1999

Granulocyte-macrophage colony-stimulating factor gene transfer to dendritic cells or epidermal cells augments their antigen-presenting function including induction of anti-tumor immunity.

Dendritic antigen-presenting cells derived from epidermis (Langerhans cells), bone marrow, and peripheral blood can present a wide variety of antigens, including tumor-associated antigens, for various immune responses. The development and function of dendritic cells is dependent upon a number of cytokines including granulocyte-macrophage-colony-stimulating factor. For example, Langerhans cells can present tumor-associated antigens for the induction of substantial in vivo anti-tumor immunity but only after activation in vitro by granulocyte-macrophage-colony-stimulating factor. Thus, we reasoned that insertion of a cDNA for granulocyte-macrophage-colony-stimulating factor into dendritic antigen-presenting cells may allow for autocrine stimulation and increased antigen-presenting capability. To test this possibility, we utilized an adenovirus vector to insert a cDNA for murine granulocyte-macrophage-colony-stimulating factor into the dendritic cell lines XS52-4D and XS106 (derived from neonatal mouse epidermis), bone marrow-derived dendritic cells, and epidermal cells that contain Langerhans cells. Infection of each of these cell types resulted in release of abundant quantities of granulocyte-macrophage-colony-stimulating factor. XS52-4D and XS106 cells infected with adenovirus granulocyte-macrophage-colony-stimulating factor exhibited prolonged dendrites and greater expression of major histocompatibility complex class II molecules and CD86 compared with cells infected with a null vector. Granulocyte-macrophage-colony-stimulating factor cDNA-containing XS cells, bone marrow-derived dendritic cells, and epidermal cells had more potent alloantigen presenting capability than cells infected with a null vector. Most importantly, granulocyte-macrophage-colony-stimulating factor gene-transferred epidermal cells were able to present tumor-associated antigens for in vivo anti-tumor immunity against challenge with the S1509a spindle-cell tumor whereas null vector-infected cells were unable to prime for immunity. These results suggest that introduction of a cDNA for granulocyte-macrophage-colony-stimulating factor into dendritic cells may be an effective means to augment their antigen-presenting capability and that granulocyte-macrophage-colony-stimulating factor gene-transfer- red epidermal cells may be useful in tumor vaccination strategies.

Animals↗

PubMed1998

Immobilization-induced and crowded environment-induced stress delay barrier recovery in murine skin.

To examine the effect of stress on skin homeostasis, cutaneous barrier recovery was measured in rate exposed to immobilization stress after tape stripping or sodium dodecyl sulphate treatment. The barrier function was evaluated by measuring transepidermal water loss. Barrier recovery was delayed in rats exposed to stress in comparison with untreated controls. This tendency was observed in both male and female animals. The delay in barrier recovery was blocked by application of the sedative drugs diazepam and chlorpromazine. The barrier recovery rate in mice which were kept at a high population density (10 animals per cage) for 2 weeks was slower than that in mice kept at lower population densities (five animals or one animal per cage). These animal models could be useful for objectively quantifying the influence of stress on the cutaneous function.

Animals↗

PubMed1998

Differential regulation of epidermal cell tumor-antigen presentation by IL-1alpha and IL-1beta.

IL-1 exists in two forms, termed IL-1alpha and IL-1beta, which exert similar effects in a number of biologic models. Recently, there have been reports of some differences in the activities of these two species in some systems. To address this issue with regard to Langerhans cells, Langerhans cell-enriched preparations of epidermal cells were treated with either IL-1alpha or IL-1beta before pulsing with S1509a tumor-associated antigens and subsequent use for immunization of naive mice to S1509a. While epidermal cells treated with 100 U IL-1beta per ml were able to induce protective tumor immunity (as indicated by the rejection of a subsequent tumor challenge with viable S1509a tumor cells), epidermal cells treated with 100 U IL-1alpha per ml failed to confer protective immunity. At 1000 U per ml, IL-1beta also inhibited the ability of epidermal cells to induce tumor immunity. To investigate the effects of the two IL-1 forms on elicitation of tumor immunity, naive mice were immunized against the S1509a tumor by s.c. injection of dead S1509a cells. Epidermal cells enriched for Langerhans cells were treated with either 100 U IL-1alpha or IL-1beta per ml before tumor-associated antigens-pulsing. Epidermal cells were then washed and injected into a hind footpad of tumor immune mice and 24 h footpad swelling was assessed as a measure of delayed-type hypersensitivity. Exposure to IL-1alpha led to suppressed elicitation of delayed-type hypersensitivity, whereas IL-1beta treated epidermal cells elicited a normal (100 U per ml) or enhanced (1000 U per ml) level of delayed-type hypersensitivity. Previous experiments indicated that the suppressive effects of IL-1alpha on induction of immunity may be mediated by TNF alpha. Therefore, the ability of IL-1alpha or IL-1beta to induce epidermal cell production of TNF alpha was assessed. IL-1alpha induced epidermal cells to secrete significantly higher amounts of TNF alpha protein compared with stimulation with IL-1beta. IL-1alpha and IL-1beta appear to differentially regulate epidermal cell antigen presenting capability.

Animals↗

PubMed1998

Modification of LC phenotype and suppression of contact hypersensitivity response by stress.

BACKGROUND: Stress is thought to exacerbate a number of diseases, some of which are skin disorders. Epidermal Langerhans' cells play a major role in cutaneous immune reactions. OBJECTIVE: The effects of two types of stress on the cutaneous immune system were to be assessed in mice. METHODS: Mice received stress by immobilization or housing at various population densities. Epidermal sheets were stained for I-A molecules (a member of class II major histocompatibility complex) and analyzed with a confocal-laser- scanning microscope. Contact hypersensitivity reaction to 2,4,6-trinitrochlorobenzene was elicited in mouse ears. RESULTS: The cell density, intensity of I-A expression, and number of dendrites were decreased as the population density increased. Elicitation of contact hypersensitivity was suppressed in mice that received either population or immobilization stress. Increased I-A expression and number of dendrites were observed in adrenalectomized compared to sham-operated mice. The population-dependent suppression of contact hypersensitivity reaction was not observed in adrenalectomized mice. After incubation with serum from mice that received either immobilization stress or population stress, the expression of I-A molecules on a XS52 Langerhans' cell-like cell line was reduced. CONCLUSION: Stress affected the cutaneous immune system. There were indications that adrenergic hormones played a role in the regulation of the system.

Adrenalectomy↗

PubMed1997

Regulation of cytokine expression in macrophages and the Langerhans cell-like line XS52 by calcitonin gene-related peptide.

Calcitonin gene-related peptide (CGRP) inhibits antigen presentation by Langerhans cells (LC) and macrophages, and LC are anatomically associated with CGRP-containing epidermal nerves. To determine whether CGRP may produce some of its functional effects through regulation of cytokine expression, we utilized enzyme-linked immunosorbent assay (ELISA) of conditioned supernatants to examine production of interleukin (IL)-10 and IL-1 beta protein in the LC-like cell line XS52 as well as the reverse transcriptase-polymerase chain reaction (RT-PCR) to examine levels of mRNA for IL-10, IL-1 beta, and the 40-kDa subunit (p40) of IL-12. CGRP augmented the lipopolysaccharide (LPS) and granulocyte-macrophage colony-stimulating factor (GM-CSF) -induced release of IL-10 protein and the induced expression of IL-10 mRNA in these cells. However, it suppressed the induction of release of IL-1 beta protein and the induction of mRNA for IL-12 p40 and IL-1 beta by LPS and GM-CSF. Regulation of cytokine expression in peritoneal macrophages was also examined. By ELISA, the LPS-induced expression of IL-10 was augmented by CGRP, whereas the induction of IL-1 beta was suppressed. Northern analysis demonstrated augmentation of LPS-induced IL-10 mRNA levels and inhibition of LPS-induced IL-1 beta mRNA by CGRP. CGRP inhibited the LPS-induced induction of IL-12 mRNA as assessed by RT-PCR. Up-regulation of B7-2 expression by LPS and GM-CSF was suppressed by CGRP in both XS52 cells and macrophages, as previously reported. This suppression, however, could be abrogated by co-culture with neutralizing antibodies to IL-10. Furthermore, the presence of neutralizing antibodies to IL-10 during exposure of epidermal cells (EC) to CGRP prevented the CGRP-mediated suppression of EC presentation of tumor-associated antigens (from the S1509a spindle cell carcinoma) for elicitation of delayed-type hypersensitivity in S1509a-immune mice. These data suggest that suppression of antigen-presenting function by CGRP is mediated, at least in part, by changes in cytokine expression that favor less robust antigen presentation for cell-mediated immunity.

Animals↗

PubMed1997

Calcitonin gene-related peptide and Langerhans cell function.

Morphologic studies have indicated that Langerhans cells (LC) are frequently in anatomic apposition with epidermal nerves containing the neuropeptide calcitonin gene-related peptide (CGRP). Experiments were undertaken to examine whether CGRP modulates LC function. The effect of pre-exposure of LC to CGRP in vitro on alloantigen presentation and specific protein presentation to a responsive T-cell line were studied using freshly prepared murine epidermal cell populations enriched for LC content (EC) by treatment with antibody to Thy-1 and complement. The ability of EC to present tumor-associated antigens for induction and elicitation of delayed-type hypersensitivity (DTH) in tumor-immune mice was also examined. Inhibitory effects of CGRP on antigen presentation were observed in each of these assays. Experiments were also performed examining the ability of intradermally administered CGRP to modulate induction of contact hypersensitivity (CHS) to a hapten applied at the injected site. Administration of CGRP led to a decrease in the CHS response after immunization at the site of injection. Intracellular cAMP was significantly increased in freshly prepared LC after exposure to CGRP, and this process could be inhibited by a specific inhibitor of the CGRP receptor, demonstrating the existence of CGRP receptors on LC. B7-2 expression induced by LPS and GM-CSF in the LC-like line XS52, and by LPS in peritoneal macrophages, was suppressed by CGRP. This suppression may account, in part, for the inhibitory effect of CGRP. As a whole, these observation suggest that regulation of antigen presentation by nerves may occur in the epidermis.

Afferent Pathways↗

PubMed1997

Calcitonin gene-related peptide inhibits proliferation and antigen presentation by human peripheral blood mononuclear cells: effects on B7, interleukin 10, and interleukin 12.

CGRP is a neuropeptide that has previously been described to possess immunosuppressive activities. CGRP is released from peripheral nerves that, in the skin, are in close physical association with dendritic APC. We sought to investigate the mechanisms by which CGRP can inhibit immune responses by studying its effects on human peripheral blood mononuclear cells (PBMC). Using allogeneic monocytes as stimulator cells, CGRP could inhibit the proliferation of PBMC by 47% when CGRP was present for the duration of culture. Interestingly, when the stimulator monocytes were incubated with CGRP for 2 h prior to irradiation then washed, the observed inhibition increased to 85%, suggesting that CGRP was exerting a direct effect on the monocyte stimulator population. Finally, the recall response to tetanus toxoid (TT) by PBMC from individuals vaccinated with TT 14 d prior was inhibited by 25-50% in the presence of CGRP. Also, CGRP decreased the levels of B7.2 but not B7.1 on treated monocytes, and this inhibition could be abrogated by the addition of anti-IL-10 antibody, suggesting that the inhibition was mediated by an increase in IL-10 production. Moreover, increased IL-10 production was confirmed by ELISA. Both IL-12 p40 and IFN-gamma levels in CGRP-treated cultures were found to be decreased by approximately 30%. The decrease in IL-12 p40 levels could be reversed by addition of anti-IL-10. These data suggest that CGRP inhibits PBMC proliferation, in part, through the release of IL-10, which in turn can downregulate important co-stimulatory molecules and the cytokines IL-12 and IFN-gamma.

Antigen Presentation↗

PubMed1997

Expression of neurotrophic factors and neuropeptide receptors by Langerhans cells and the Langerhans cell-like cell line XS52: further support for a functional relationship between Langerhans cells and epidermal nerves.

Epidermal Langerhans cells are frequently anatomically associated with calcitonin gene-related peptide-containing nerves. Furthermore, calcitonin gene-related peptide inhibits Langerhans cells antigen-presenting function in several assays. Studies were performed to further explore the hypothesis that Langerhans cells and nerves have a functional relationship. To examine whether Langerhans cells may produce factors that influence nerve cell differentiation, we utilized the Langerhans cell-like cell line XS52 as a surrogate for Langerhans cells and compared it with Langerhans cells enriched to 90%. Supernatants conditioned by lipopolysaccharide-stimulated XS52 cells were able to induce the differentiation of the pheochromocytoma line PC12 into sympathetic neuron-like cells. This was also the case with enriched Langerhans cells stimulated by lipopolysaccharide. Pretreatment of conditioned supernatants with specific neutralizing anti-sera indicated that most of the differentiation-inducing activity was due to interleukin-6 and a small amount was due to nerve growth factor and basic fibroblast growth factor. By reverse transcriptase polymerase chain reaction, three clones of the XS52 cell line, XS52-4D, XS52-11D, and XS52-8B, were found to express mRNA for interleukin-6 and expression was markedly augmented by lipopolysaccharide. mRNA for nerve growth factor and basic fibroblast growth factor was detected in XS52-4D and XS52-11D, but not in XS52-8B. The expression of these neurotrophic factors by enriched Langerhans cells was quite similar to that of XS52-4D. In order to examine whether Langerhans cells may express receptors for nerve-derived peptides, reverse transcriptase polymerase chain reaction was employed to look for pituitary adenylate cyclase activating polypeptide type I, type II, and type III, and gastrin-releasing peptide receptors. All clones examined, as well as enriched Langerhans cells, expressed pituitary adenylate cyclase activating polypeptide type II and type III, and gastrin-releasing peptide receptors. These results suggest bi-directional signalling between Langerhans cells and nerves; nerve cells may regulate Langerhans cell function by elaboration of certain neuropeptides whereas Langerhans cells may promote the differentation of nerves by elaboration of interleukin-6 and, possibly, other factors.

Animals↗

PubMed1996

Langerhans cells express inducible nitric oxide synthase and produce nitric oxide.

The importance of nitric oxide (NO) in mediating macrophage functions has been demonstrated, but production of this potent gas has not been examined in Langerhans cells (LC). Using murine LC purified from epidermal cell suspensions and the recently established LC-like cell line derived from newborn BALB/c epidermis (XS-52), it was shown with reverse transcriptase (RT)-PCR that inducible nitric oxide synthase (iNOS) message is present in these cells. Murine keratinocytes did not contain iNOS message. iNOS mRNA was increased in a concentration-dependent manner by lipopolysaccharide (LPS) in purified murine LC and XS-52 cells, and immunofluorescence using an antibody to iNOS revealed bright cytoplasmic staining in LPS-treated XS-52 cells. Anti-iNOS antibody brightly stained LC on human neonatal foreskin cryosections. An increase in NO production by LPS-treated XS-52 cells over 16 h, as measured by the determination of nitrite levels in culture supernatants using the Griess Reaction, was observed. Interferon-gamma (IFNgamma) did not affect NO production on its own. In the presence of LPS and IFNgamma, NO production was 3 times more than observed with LPS alone. NO production was inhibited by the NOS inhibitor L-NAME. Western blots with anti-iNOS antibody demonstrated an increase in iNOS expression in LPS-treated XS-52 cells that was suppressed by IL-10. NO produced in LC may affect LC functions such as microbicidal activity, antigen presentation, and cytotoxicity and may affect adjacent keratinocytes and melanocytes.

Animals↗

PubMed1996

Impaired immunosuppressive response to ultraviolet radiation in interleukin-10-deficient mice.

Exposure to mid-range ultraviolet radiation (UVR) [280-320 nm, ultraviolet B (UVB) radiation] inhibits the acquisition of delayed-type hypersensitivity in mice and contact hypersensitivity in rodents and humans. Intraperitoneal administration of interleukin 10 (IL-10) inhibits the sensitization of mice to alloantigens for a delayed-type hypersensitivity reaction and administration of neutralizing antibodies to IL-10 largely, but not totally, blocks the UVR-mediated suppression of the ability to sensitize mice. This suggests that these inhibitory effects of UVB radiation may be mediated by release of IL-10. To test this hypothesis directly, IL-10 gene-targeted (IL-10T) mice lacking expression of IL-10 were examined for the ability of UVB radiation to suppress induction of delayed-type hypersensitivity to alloantigens. IL-10T mice were completely resistant to UVB-induced immunosuppression in this system. Interestingly, UVB radiation could suppress in IL-10T mice the induction of contact hypersensitivity to a hapten applied to the skin at a site distant of irradiation, supporting the concept that regulation pathways of delayed-type hypersensitivity and contact hypersensitivity responses by UVR differ. These data provide additional understanding of the mechanisms of immunosuppression induced by UVR and suggest that IL-10 release subsequent to UVB radiation may play a role in the growth immunogenic UVB-induced cutaneous malignancies in the primary host.

Animals↗

PubMed1995

Specific induction of cAMP in Langerhans cells by calcitonin gene-related peptide: relevance to functional effects.

Epidermal Langerhans cells (LC) are associated anatomically with epidermal nerves, and a product of these nerves, calcitonin gene-related peptide (CGRP), inhibits the antigen-presenting capacity of LC and macrophages. As the CGRP receptor appears to be coupled to Gs alpha protein, which in turn activates adenylate cyclase, the ability of CGRP to induce cAMP in LC was examined and correlated with functional effects. LC were isolated from murine epidermal cells using antibodies on magnetic microspheres. Exposure to CGRP induced a significant increase in cAMP content, which could be inhibited by coculture with a truncated form of CGRP [CGRP-(8-37)] that is a specific competitive inhibitor of CGRP. Substance P and calcitonin failed to induce cAMP in LC. Although culture in CGRP reduced the ability of murine epidermal cells enriched for LC content to present pigeon cytochrome c to a responsive clone or to present antigen for elicitation of delayed-type hypersensitivity in immune mice, culture in forskolin had little or no effect on antigen presentation despite increased cAMP content of LC as much or more than that induced by CGRP. The effect of CGRP on antigen presentation in these systems could be blocked with CGRP-(8-37). CGRP inhibited the induction of B7-2 by lipopolysaccharide on peritoneal macrophages and a LC line, whereas calcitonin did not. CGRP induces specific accumulation of cAMP in LC and inhibits LC antigen-presenting function by a receptor-mediated event. However, the induction of cAMP by itself does not account for inhibition of antigen presentation. Suppression of the expression of B7-2 may be one mechanism by which CGRP inhibits antigen presentation.

Animals↗

PubMed1995

Inhibition of the induction of delayed-type and contact hypersensitivity by calcitonin gene-related peptide.

Calcitonin gene-related peptide (CGRP)-containing nerves are frequently associated anatomically with epidermal Langerhans cells (LC), and LC Ag-presenting function is down-regulated by CGRP. To investigate possible regulation of cutaneous immunity by CGRP, we examined its effect on the induction of delayed-type hypersensitivity (DTH) and contact hypersensitivity (CHS). A system of immunity to the murine spindle cell tumor S1509a (H-2a) was employed to examine induction of DTH by LC. This system requires exposure of epidermal cells (EC) to GM-CSF for induction of substantial immunity. EC were prepared from CAF1 mice (H-2a/d) and Thy-1+ cells deleted. EC were exposed for 16 h to GM-CSF with or without CGRP. EC were then pulsed with tumor-associated Ags (TAA), washed, and injected s.c. into mice three times at 7-day intervals for immunization. Mice were challenged for a DTH response by injection of a hind footpad with TAA-pulsed EC, and 24-h footpad swelling assessed. Exposure of EC to CGRP significantly inhibited induction of DTH. To examine the effect of CGRP administered in vivo on induction of immunity, 530 pmol of CGRP or diluent alone was injected intradermally into the dorsum of the left ear of naive mice 8 h and 3 h before epicutaneous application of a hapten at the injected site. Mice were challenged on the right ear 7 days later and 24 h ear swelling was assessed. CGRP significantly inhibited the induction of CHS whereas calcitonin had no effect. Furthermore, when hapten was applied at a site distant from CGRP administration, no inhibition of CHS was observed, suggesting that the effect of CGRP is local. These data support the concept that CGRP may be an endogenous regulator of immune function and also suggest the possibility that CGRP or its analogues administered in vivo might have therapeutic utility as immunomodulators.

Animals↗

PubMed1995

IL-10 inhibits tumor antigen presentation by epidermal antigen-presenting cells.

IL-10 inhibits Langerhans cell (LC) Ag presentation to Th1 clones. As LC are capable of presenting tumor-associated Ags (TAA) for primary and secondary tumor immune responses, we examined the effect of IL-10 on LC Ag presentation in a model of immunity to the S1509a spindle cell tumor (H-2a). Because induction of immunity to S1509a requires exposure of LC to granulocyte-macrophage (GM)-CSF, this system also allowed us to study the regulatory interactions of GM-CSF and IL-10 on LC. Naive CAF1 (H-2a/d) mice could be immunized against S1509a by injection with GM-CSF-exposed and TAA-pulsed epidermal cells (EC) as assessed by inhibition of the growth of inoculated tumor cells. Incubation of EC in IL-10 before GM-CSF exposure completely inhibited Ag presentation in this system. Significantly, neither co-incubation of EC in IL-10 and GM-CSF (without preincubation in IL-10) nor IL-10 treatment after GM-CSF incubation was able to exert a down-regulatory effect. The ability of IL-10 to modulate EC presentation of TAA for a secondary immune response was also examined. EC were pulsed with TAA in vitro and then injected into a hind footpad of tumor-immune mice with 24 h swelling assessed as a measure of delayed-type hypersensitivity. Preincubation in IL-10 before TAA exposure significantly inhibited elicitation of delayed-type hypersensitivity with or without subsequent exposure to GM-CSF. Co-incubation of EC in IL-10 and GM-CSF or exposure to IL-10 after GM-CSF led to a normal response. These data indicate that IL-10 may serve as an important regulator of LC Ag-presenting function for tumor immune responses. IL-10 appears to specifically prevent the GM-CSF-induced maturation of LC Ag-presenting function when treatment with IL-10 occurs before exposure to GM-CSF but does not reverse the established mature state.

Animals↗