Effects of dietary lactosucrose (4G-beta-D-galactosylsucrose) on the IgE response in mice

In this study, we examined the effects of dietary lactosucrose (LS, a non-digestible oligosaccharide) on the IgE response in mice immunized with ovalbumin (OVA)/alum. In addition to IgG1 and IgG2a responses, the anti-OVA IgE response in mice fed LS diets was dose-dependently suppressed, as compared with the control mice, while the serum total IgG levels were comparable. Moreover, dietary LS feeding inhibited antigen-specific IgE and IgG1 productions even after a second immunization. Regarding with cytokine production, when stimulated in vitro with OVA, splenocytes obtained from LS-fed mice produced a similar level of IFN-gamma, and lower levels of IL-4 and IL-5, as compared with the control mice. But IL-10 production by OVA-stimulated splenocytes was augmented in LS-fed mice, suggesting that IL-10 producing cells are responsible for the immunoregulatory effect of LS. Our findings indicate the further possibility that dietary LS supplementation can be used to prevent IgE-mediated allergic diseases.     

IL-12 receptor beta 2 (IL-12R beta 2)-deficient mice are defective in IL-12-mediated signaling despite the presence of high affinity IL-12 binding sites

Two subunits of the IL-12 receptor (IL-12R), IL-12R beta 1 and IL-12R beta 2, have been identified and cloned. Previous studies demonstrated that the IL-12R beta 1 subunit was required for mouse T and NK cells to respond to IL-12 in vivo. To investigate the role of IL-12R beta 2 in IL-12 signaling, we have generated IL-12R beta 2-deficient (IL-12R beta 2(-/-)) mice by targeted mutation in embryonic stem (ES) cells. Although Con A-activated splenocytes from IL-12R beta 2(-/-) mice still bind IL-12 with both high and low affinity, no IL-12-induced biological functions can be detected. Con A-activated splenocytes of IL-12R beta 2(-/-) mice failed to produce IFN-gamma or proliferate in response to IL-12 stimulation. NK lytic activity of IL-12R beta 2(-/-) splenocytes was not induced when incubated with IL-12. IL-12R beta 2(-/-) splenocytes were deficient in IFN-gamma secretion when stimulated with either Con A or anti-CD3 mAb in vitro. Furthermore, IL-12R beta 2(-/-) mice were deficient in vivo in their ability to produce IFN-gamma following endotoxin administration and to generate a type 1 cytokine response. IL-12-mediated signal transduction was also defective as measured by phosphorylation of STAT4. These results demonstrate that although mouse IL-12R beta 1 is the subunit primarily responsible for binding IL-12, IL-12R beta 2 plays an essential role in mediating the biological functions of IL-12 in mice.     

IL-28 elicits antitumor responses against murine fibrosarcoma

IL-28 is a recently described antiviral cytokine. In this study, we investigated the biological effects of IL-28 on tumor growth to evaluate its antitumor activity. IL-28 or retroviral transduction of the IL-28 gene into MCA205 cells did not affect in vitro growth, whereas in vivo growth of MCA205IL-28 was markedly suppressed along with survival advantages when compared with that of controls. When the metastatic ability of IL-28-secreting MCA205 cells was compared with that of controls, the expression of IL-28 resulted in a potent inhibition of metastases formation in the lungs. IL-28-mediated suppression of tumor growth was mostly abolished in irradiated mice, indicating that irradiation-sensitive cells, presumably immune cells, are primarily involved in the IL-28-induced suppression of tumor growth. In vivo cell depletion experiments displayed that polymorphonuclear neutrophils, NK cells, and CD8 T cells, but not CD4 T cells, play an equal role in the IL-28-mediated inhibition of in vivo tumor growth. Consistent with these findings, inoculation of MCA205IL-28 into mice evoked enhanced IFN-gamma production and cytotoxic T cell activity in spleen cells. Antitumor action of IL-28 is partially dependent on IFN-gamma and is independent of IL-12, IL-17, and IL-23. IL-28 increased the total number of splenic NK cells in SCID mice and enhanced IL-12-induced IFN-gamma production in vivo and expanded spleen cells in C57BL/6 mice. Moreover, IL-12 augmented IL-28-mediated antitumor activity in the presence or absence of IFN-gamma. These findings indicate that IL-28 has bioactivities that induce innate and adaptive immune responses against tumors.     

The production of IFN-gamma by IL-12/IL-18-activated macrophages requires STAT4 signaling and is inhibited by IL-4

Macrophages release IFN-gamma on combined stimulation with IL-12 and IL-18, but the signaling requirements of this process and its regulation by other cytokines are unknown. Here, we demonstrate that STAT4 is indispensable for IL-12/IL-18-induced production of IFN-gamma by mouse peritoneal macrophages. Type 2 NO synthase (NOS2), which we previously found to be a prerequisite for IL-12-induced IFN-gamma production in NK cells, was not required for IFN-gamma production by these macrophages. IL-12 alone already induced the expression of IFN-gamma mRNA, but nuclear translocation of STAT4, the release of IFN-gamma protein, and the subsequent production of NO was strictly dependent on the simultaneous presence of IL-18. NF-kappa B, which mediates IL-18 effects in T cells, was only weakly activated by IL-12 and/or IL-18 in macrophages. Known inhibitors of macrophage functions (e.g., IL-4 and TGF-beta) also suppressed macrophage IFN-gamma production and the subsequent production of NOS2-derived NO. The inhibitory effect of IL-4 was paralleled by nuclear translocation of STAT6, which in EMSAs was able to bind to the same DNA oligonucleotide as STAT4. These results further define the production of IFN-gamma by macrophages and point to a diversity in the signals required for IFN-gamma production by various cell types.     

Absence of functional inducible NO synthase enhances the efficacy of tolerance induced by high dose antigen feeding

Recent studies have suggested that IL-12 and IFN-gamma may impair the ability of fed Ag to induce systemic tolerance. Because both of these cytokines can function to directly or indirectly induce inducible NO synthase (iNOS) expression, we have investigated whether the functional expression of iNOS regulates oral tolerance. C57BL/6J wild-type or C57BL/6J NOS2(-/-) mice were gavaged with a single dose of 20 mg of keyhole limpet hemocyanin (KLH), followed by s.c. immunization with KLH/CFA. In the absence of feeding Ag, several parameters of the immune response were more robust in C57BL/6J NOS2(-/-) mice following KLH/CFA immunization, including the magnitude of the delayed-type hypersensitivity response, the proliferative response, and the production of IFN-gamma and IL-2 by Ag-activated draining lymph node cells. These heightened responses in the C57BL/6J NOS2(-/-) mice are still effectively inhibited by feeding KLH. Feeding KLH to the C57BL/6J NOS2(-/-) mice elicited heightened TGF-ss1 production by Ag-activated lymphocytes, as well as augmented total IgG, IgG1, and IgG2a responses to KLH/CFA compared with that seen in Ag-fed wild-type mice. Feeding Ag to the NOS2(-/-) mice suppressed proliferative responses and IFN-gamma production, while increasing IL-4 production and the IgG1/IgG2a ratio even following a booster immunization of KLH/CFA. Administrating L-N:(6)-(1-iminoethyl)-lysine. 2HCl to wild-type mice during the period of Ag feeding reproduced the high TGF-ss1 production seen in Ag-activated lymphocytes from Ag-fed NOS2(-/-) mice. Feeding KLH is followed by transient up-regulation of NOS2 mRNA expression in the Peyer's patches of wild-type mice. Selective inhibition of NOS2 may be a simple way to augment tolerogenic mucosal immune responses.     

Dietary conjugated linoleic acid decreased cachexia,macrophage tumor necrosis factor-alpha production,and modifies splenocyte cytokines production

The effect of conjugated linoleic acid (CLA) on macrophage functions were studied in vitro, in vivo, and ex vivo. In RAW macrophage cell line, CLA (mixed isomers) was shown to inhibit lipopolysaccharide (LPS)-stimulated tumor necrosis factor-alpha (TNF-alpha) production. Two CLA isomers, c9,t11 and t10,c12, were tested on RAW cells and it was found that the c9,t11 was the isomer responsible for the inhibition of LPS-induced TNF-alpha production. BALB/c mice were used to determine the effect of dietary CLA on body weight wasting and feed intake after LPS injection. CLA was protective against LPS-induced body weight wasting and anorexia. Plasma TNF-alpha levels after LPS injection were lower in the CLA group compared with the corn oil-fed control group 2 hr post-LPS injection. In a separate experiment, 30 mice were fed a CLA-supplemented diet or a corn oil-supplemented diet for 6 weeks and peritoneal resident macrophages were obtained for measuring TNF-alpha and nitric oxide production after in vitro exposure to interferon-gamma (IFN-gamma) and/or LPS. TNF-alpha production was not found to be different in peritoneal macrophages from mice fed the dietary treatments, but less nitric oxide was produced in macrophages from CLA-fed mice upon stimulation when compared with macrophages from control-fed mice. Splenocytes were also collected from the mice fed the dietary treatments and stimulated to produce cytokines in culture. Supernatant was used to run cytokine enzyme-linked immunoabsorbant assays. Interleukin-4 (IL-4) was decreased in CLA-fed mice when splenocytes were stimulated with concanavalin A (Con A) for 44 hr; however, IL-2 and the IL-2-to-IL-4 ratio were elevated.     

Antitumor effect of heat-killed Lactobacillus plantarum L-137 through restoration of impaired interleukin-12 production in tumor-bearing mice

 We have previously reported that heat-killed Lactobacillus plantarum L-137 is a potent inducer of interleukin-12 (IL-12) in vivo as well as in vitro in mice. In order to develop effective usage of L. plantarum L-137 for tumor immunotherapy, we examined its antitumor effect against DBA/2 mice inoculated with syngenic P388D1 tumor cells in different treatment schedules. Daily injection of L. plantarum L-137 from the day of tumor inoculation induced a steep increase in plasma IL-12 only after the first injection but not after subsequent injections, and had no effect on tumor growth and survival time. In contrast, daily injection of L. plantarum L-137 from the 7th day after tumor inoculation exerted a marked antitumor effect but such an effect was not evident in mice treated with L. plantarum L-137 twice a week from the 7th day. IL-12 production was considerably impaired at the first injection but steeply increased after the third injection in the mice injected daily with L. plantarum L-137 from the 7th day. Our results suggest that daily administration of L. plantarum L-137 is required to exert an antitumor effect at the late stages of tumor development when IL-12 production is considerably impaired. Received: 15 July 1999 / Accepted: 28 January 2000     

Mouse CD8+ CD122+ T cells with intermediate TCR increasing with age provide a source of early IFN-gamma production

Although CD8+ IL-2Rbeta (CD122)+ T cells with intermediate TCR reportedly develop extrathymically, their functions still remain largely unknown. In the present study, we characterized the function of CD8+ CD122+ T cells with intermediate TCR of C57BL/6 mice. The proportion of CD8+ CD122+ T cells in splenocytes gradually increased with age, whereas CD8+ IL-2Rbeta-negative or -low (CD122-) T cells conversely decreased. The IFN-gamma production from splenocytes stimulated with immobilized anti-CD3 Ab in vitro increased with age, whereas the IL-4 production decreased. When sorted CD8+ CD122+ T cells were stimulated in vitro by the anti-CD3 Ab, they promptly produced a much larger amount of IFN-gamma than did CD8+ CD122- T cells or CD4+ T cells, whereas only CD4+ T cells produced IL-4. The depletion of CD8+ CD122+ T cells from whole splenocytes greatly decreased the CD3-stimulated IFN-gamma production and increased the IL-4 production, whereas the addition of sorted CD8+ CD122+ T cells to CD8+ CD122+ T cell-depleted splenocytes restored the IFN-gamma production and partially decreased IL-4 production. It is of interest that CD8+ CD122+ T cells stimulated CD4+ T cells to produce IFN-gamma. The CD3-stimulated IFN-gamma production from each T cell subset was augmented by macrophages. Furthermore, CD3-stimulated CD8+ CD122+ T cells produced an even greater amount of IFN-gamma than did liver NK1.1+ T cells and also showed antitumor cytotoxicity. These results show that CD8+ CD122+ T cells may thus be an important source of early IFN-gamma production and are suggested to be involved in the immunological changes with aging.     

Characterization of protective immunity induced against Schistosoma mansoni via DNA priming with the large subunit of calpain (Sm-p80) in the presence of genetic adjuvants

Despite advances in control via snail eradication and large-scale chemotherapy using praziquental, schistosomiasis continues to spread to new geographic areas particularly in sub-Saharan Africa. Presently, there is no vaccine for controlling this disease. We have concentrated on a functionally important schistosome antigen Sm-p80 as a possible vaccine candidate for schistosomiasis. Here we report the proliferation of spleen cells in response to the recombinant Sm-p80 protein and cytokine (IFN-gamma and IL-4) production by the splenocytes. These spleen cells were obtained from groups of mice that were vaccinated with a DNA vaccine formulation containing Sm-p80 and one of the Th-1 (IL-2 or IL-12) or Th-2 (GM-CSF, IL-4) enhancer cytokines. The splenocytes from the groups of mice vaccinated with Sm-p80 DNA in the presence of Th-2 enhancer cytokines showed moderate but detectable proliferation. The splenocytes obtained from mice vaccinated with Sm-p80 DNA with Th-1 enhancer cytokines IL-2 and IL-12 provided the highest proliferation. The IFN-gamma production by splenocytes was found to follow the similar pattern [(Sm-p80) < (Sm-p80 + IL-4) < (Sm-p80 + GMCSF) < (Sm-p80 + IL-12) < (Sm-p80 + IL-2)], as has been observed for the proliferation and protection data. However, the elevated IL-4 production was inversely correlated to Sm-p80-induced splenocyte proliferation or the protection. These results show again that protective immune response induced by Sm-p80 is of Th-1 type.     

Cutting edge: IL-15 costimulates the generalized Shwartzman reaction and innate immune IFN-gamma production in vivo

Sequential administration of LPS to SCID mice results in the generalized Shwartzman reaction, manifesting as rapid mortality via cytokine-induced shock. Here we demonstrate that in vivo neutralization of IL-15 before LPS priming significantly reduced lethality in this reaction (p = 0.0172). We hypothesize that LPS priming induces IL-12 and IL-15 that costimulate NK cell-derived IFN-gamma. Such IFN-gamma may then in turn sensitize macrophages to elicit the Shwartzman reaction following a subsequent LPS challenge. Supporting this, IL-12 and IL-15 synergized to induce murine NK cell IFN-gamma production in vitro. LPS stimulation of SCID mouse splenocytes resulted in measurable IFN-gamma production, which was reduced when IL-15 was neutralized or IL-2/15Rbeta was blocked. Pretreatment with either anti-IL-2/15Rbeta or anti-IL-15 Abs reduced serum IFN-gamma protein following LPS administration to SCID mice. Collectively, these data provide the first in vivo evidence that IL-15 participates in LPS-induced innate immune IFN-gamma production and significantly contributes to the lethal Shwartzman reaction.     

Inherited IL-12 unresponsiveness contributes to the high LPS resistance of the Lps(d) C57BL/10ScCr mouse

LPS(d) mouse strains are characterized by the presence of a defective LPS/tlr4 gene that make them refractory to the biological activity of LPS. One of the mouse strains commonly used to study LPS defects is the C57BL/10ScCr (Cr) strain. However, unlike other LPS(d) strains, the Cr strain also has a heavily impaired IFN-gamma response to micro-organisms. As a consequence, unlike other LPS(d) mouse strains, they do not acquire a partial LPS susceptibility when treated with sensitizing bacteria. Because IL-12 is important for the microbial induction of IFN-gamma, we investigated whether the production or function of IL-12 might be defective in Cr mice. IL-12 mRNA (p35 and p40) was present in the spleen of untreated Cr mice, IL-12p40 mRNA was inducible in mice injected with live or killed Salmonella typhimurium, and IL-12 (p70) was inducible in macrophages by bacteria. Thus, Cr mice exhibit normal IL-12 responses. In functional tests, splenocytes of untreated or of S. typhimurium-infected mice failed to produce IFN-gamma when stimulated with murine rIL-12 or with a combination of IL-12 and murine rIL-18 or Con A. Furthermore, Cr mice were identical with IL-12p35/p40 and IL-12 receptor beta(1) knockout mice in their impaired in vivo and in vitro IFN-gamma responses to bacteria. Thus, Cr mice carry a second genetic defect unrelated to the Lps/tlr4 mutation that underlies the IL-12 unresponsiveness and contributes to the LPS resistance and impaired innate immune response in this strain.     

IL-12-independent IFN-gamma production by T cells in experimental Chagas' disease is mediated by IL-18.

IL-12p35-deficient (IL-12p35(-/-)) mice were highly susceptible to Trypanosoma cruzi infection and succumbed during acute infection, demonstrating the crucial importance of endogenous IL-12 in resistance to experimental Chagas' disease. Delayed immune responses were observed in mutant mice, although comparable IFN-gamma and TNF-alpha blood levels as in wild-type mice were detected 2 wk postinfection. In vivo and in vitro analysis demonstrated that T cells, but not NK cells, were recruited to infected organs. Analysis of mice double deficient in the recombinase-activating gene 2 (RAG2) and IL-12p35, as well as studies involving T cell depletion, identified CD4(+) T cells as the cellular source for IL-12-independent IFN-gamma production. IL-18 was induced in IL-12p35(-/-) mice and was responsible for IFN-gamma production, as demonstrated by in vivo IL-18 neutralization studies. In conclusion, evidence is presented for an IL-12-independent IFN-gamma production in experimental Chagas' disease that is T cell and IL-18 dependent.     

Augmentation of effector CD8+ T cell generation with enhanced granzyme B expression by IL-27

IL-27 is a novel IL-12 family member that plays a role in the early regulation of Th1 initiation. We have recently demonstrated that IL-27 has a potent antitumor activity, which is mainly mediated through CD8+ T cells, and also has an adjuvant activity to induce epitope-specific CTL in vivo. In this study, we further investigated the in vitro effect of IL-27 on CD8+ T cells of mouse spleen cells. In a manner similar to CD4+ T cells, IL-27 activated STAT1, -2, -3, -4, and -5, and augmented the expression of T-bet, IL-12Rbeta2, and granzyme B, and slightly that of perforin in naive CD8+ T cells stimulated with anti-CD3. IL-27 induced synergistic IFN-gamma production with IL-12 and proliferation of naive CD8+ T cells. Moreover, IL-27 enhanced proliferation of CD4+ T cell-depleted spleen cells stimulated by allogeneic spleen cells and augmented the generation of CTL. In STAT1-deficient naive CD8+ T cells, IL-27-induced proliferation was not reduced, but synergistic IFN-gamma production with IL-12 was diminished with decreased expression of T-bet, IL-12Rbeta2, granzyme B, and perforin. In T-bet-deficient naive CD8+ T cells, IL-27-induced proliferation was hardly reduced, but synergistic IFN-gamma production with IL-12 was diminished with decreased expression of IL-12Rbeta2, granzyme B, and perforin. However, IL-27 still augmented the generation of CTL from T-bet-deficient CD4+ T cell-depleted spleen cells stimulated by allogeneic spleen cells with increased granzyme B expression. These results suggest that IL-27 directly acts on naive CD8+ T cells in T-bet-dependent and -independent manners and augments generation of CTL with enhanced granzyme B expression.     

IFN-gamma-inducing factor (IL-18) increases allergic sensitization, serum IgE, Th2 cytokines, and airway eosinophilia in a mouse model of allergic asthma

We investigated the effects of IFN-gamma-inducing factor (IL-18) in a ragweed (RW) mouse model of allergic asthma. Administration of IL-18 in conjunction with allergic sensitization and challenge in wild-type, but not IFN-gamma -/- mice, inhibited the bronchoalveolar lavage (BAL) eosinophilia induced by RW challenge, and increased serum levels of RW-specific IgG2a and production of IFN-gamma from splenocytes cultured with RW, indicating a critical role for IFN-gamma in mediating these effects. Paradoxically, the same treatment schedule in WT mice increased serum levels of RW-specific IgE and IgG1, and production of IL-4 and IL-5 from splenocytes cultured with RW. When the effects of the same IL-18 treatment schedule were allowed to mature for 3 wk, the inhibition of lung eosinophil recruitment was replaced by augmentation of lung eosinophil recruitment. In another experiment, IL-18 administered only with allergic sensitization increased BAL eosinophilia and lung expression of IL-5 and IFN-gamma, while IL-18 administered only with RW challenge decreased BAL eosinophilia and increased lung IFN-gamma expression, while lung expression of IL-5 remained unchanged. IL-18 administered without RW or adjuvant to naive mice increased total serum IgE levels. Finally, intrapulmonary administrations of IL-18 plus RW in naive mice dramatically increased Th2 cytokine production, IgE levels, eosinophil recruitment, and airway mucus, demonstrating induction of allergic sensitization. This is the first report demonstrating that IL-18 promotes a Th2 phenotype in vivo, and potently induces allergic sensitization. These results suggest that IL-18 may contribute to the pathogenesis of allergic asthma.     

The in vivo antiviral activity of interleukin-12 is mediated by gamma interferon.

The injection of 20 ng of mouse interleukin-12 (IL-12) protects mice from a lethal infection with encephalomyocarditis virus. In vitro, an anti-gamma interferon (anti-IFN-gamma) monoclonal antibody but not an anti-IL-12 monoclonal antibody neutralizes the antiviral activity present in the supernatants of splenocytes stimulated with IL-12. Finally, IL-12 fails to protect 129 Sv/Ev IFN-gamma R0/0 mice against encephalomyocarditis virus infection. These results demonstrate that IL-12 exerts its antiviral activity through the induction of endogenous IFN-gamma.     

Interleukin-12 but not interleukin-18 is required for immunity to Trypanosoma cruzi in mice

Protective immunity to the parasite Trypanosoma cruzi in mice depends on a pro-inflammatory T cell response involving the production of interferon-gamma (IFN-gamma). In conjunction with interleukin-12 (IL-12), IL-18 promotes the synthesis of IFN-gamma and a T helper type 1 immune response. We investigated the requirements of IL-12 and IL-18 in murine T. cruzi infection by use of C57BL/6 mice genetically deficient in either cytokine. IL-12p40(-/-) mice succumbed to infection at doses of 100 parasites, whereas IL-18(-/-) and wild-type mice resisted infectious doses up to 1000 parasites to the same extent. Levels of parasitemia were comparable between the latter groups, as were tissue parasite burdens according to quantitative real-time PCR. In contrast, IL-12p40(-/-) mice displayed vastly increased levels of parasites both in blood and in tissue. IFN-gamma concentrations in the serum of infected mice and in supernatants of splenocytes stimulated in vitro were decreased in IL-18(-/-) mice, whereas in IL-12p40(-/-) mice, IFN-gamma was undetectable in the serum and drastically reduced in cell supernatants. Levels of IL-12 production were generally comparable between wild-type and IL-18(-/-) mice, as were levels of IL-4, IL-2 and nitric oxide. Thus, the requirement for endogenous pro-inflammatory cytokines for a protective murine immune response against T. cruzi is satisfied by the expression of IL-12, while IL-18 is dispensable.     

Prostaglandin E2-mediated suppression of murine lymphokine-activated killer cell activity generated from tumor-bearing hosts by interferon-gamma

The effect of mouse recombinant interferon-gamma (IFN-gamma) on murine lymphokine-activated killer (LAK) cell activity was investigated using a natural killer-resistant, LAK-sensitive, spontaneously developed, weakly immunogenic, syngeneic murine mammary adenocarcinoma, a tumor model mimicking that of human disease. When all of the splenocytes prepared from tumor-bearing mice were cultured with recombinant interleukin-2 (IL-2) and IFN-gamma, LAK cell activity was suppressed in an IFN-gamma dose-dependent manner. An increase in the prostaglandin E2 (PGE2) content in the corresponding culture media was detected, as was IFN-gamma dose dependent. The suppression of generation of LAK cell activity by IFN-gamma was abrogated, accompanied by the elimination of the increase in PGE2 content, when plastic dish and nylon wool-treated nonadherent macrophage-depleted splenocytes were used. These results indicated that IL-2-induced LAK cell activity generated from the splenocytes of tumor-bearing mice was suppressed by IFN-gamma, and that PGE2 secreted from the macrophages of the splenocyte cultures served as the mediator in this IFN-gamma dose-dependent suppression of IL-2-induced LAK cell activity.     

Branched-chain amino acid-enriched diet: effects on insulin secretion and cellular immune aggression

Several reports have demonstrated that high-protein diets may have beneficial effects on experimental models of diabetes and have raised the possibility that branched-chain amino acids could play a role in these protective effects. We investigated the effect of a normoproteic, branched-chain amino acid-enriched diet (experimental diet) on insulin secretion from C57BL/6N mice transferred with splenocytes from diabetic syngeneic donors. Mice previously fed with the experimental or control diet received three intraperitoneal injections, every other day, of 5 x 107 viable mononuclear splenocytes obtained from control or diabetic donors. Results showed that mice fed with the experimental diet and transferred with "diabetic" splenocytes presented: i) normoglycemia, and (ii) significantly higher levels in both phases of glucose-induced insulin secretion and normal values of arginine-glucose-induced insulin secretion. To evaluate the in vitro cellular immune aggression, dispersed mouse islet cells were co-cultured with splenocytes from syngeneic diabetic mice. First, dispersed islet cells from mice on the experimental or control diet were co-cultured with splenocytes from control or diabetic mice on a commercial diet. In the presence of "diabetic splenocytes, dispersed islet cells from mice on the experimental diet presented a significantly lower in vitro cellular immune aggression. On the other hand, "diabetic" splenocytes from mice fed with the experimental diet produced a significantly reduced cellular immune aggression on dispersed islet cells. Our results showed that feeding branched-chain amino acids increased the capacity of beta cells to withstand a functional assault and diminished the extent of in vitro cellular immune aggression.