The endogenous danger signal uric Acid augments contact hypersensitivity responses in mice.

OBJECTIVE: The danger hypothesis proposes that the immune system responds not only to foreign antigens but also to damaged cells or tissues. Recently, uric acid crystals (monosodium urate, MSU) from necrotic cell lysates were identified as a danger signal for dendritic cells (DCs). Our aim was to determine whether MSU modulates immune responses in the skin. METHOD: We analyzed the effect of MSU on trinitrochlorobenzene-induced contact hypersensitivity responses using BALB/c mice administered potassium oxonate, an uricase inhibitor, to prevent MSU degradation. Ear swelling response after elicitation and activation profiles of DCs and T cells in draining lymph nodes after sensitization were assessed. RESULTS: Intradermal administration of MSU augmented the ear swelling response in potassium oxonate-administered mice and enhanced expression of CD86 and CD40 molecules on DCs in the lymph nodes. Activation of DCs was followed by an increase in CD69+ and CD44+ T cells in CD4+ and/or CD8+ subsets in the lymph nodes 4 days after trinitrochlorobenzene sensitization. CONCLUSION: These observations demonstrate that MSU is an endogenous danger signal, which augments the contact hypersensitivity response in mice. MSU released from damaged skin may act as an endogenous adjuvant to augment immune response.

Keratinocyte-derived, CD80-mediated costimulation is associated with hapten-specific IgE production during contact hypersensitivity to TH1 haptens.

Background B7-1 transgenic mice exhibit exaggerated and persistent contact hypersensitivity responses compared with normal mice. Objective Because B7-1 and B7-2 deliver different costimulatory signals to T cells during antigen presentation, the purpose of this study was to compare B7-1 and B7-2 on keratinocytes and to compare their effects on contact hypersensitivity. Methods Contact hypersensitivity was studied in transgenic mice whose keratinocytes constitutively expressed B7-1, B7-2, or no costimulatory molecules (nontransgenic mice). Results B7-1 transgenic mice, and to a lesser extent B7-2 transgenic mice, developed exaggerated ear swelling responses after sensitization and challenge with haptens such as trinitrochlorobenzene or dinitrofluorobenzene. Ear swelling responses in B7-1 transgenic mice were characterized by the presence of markedly elevated inflammatory cytokine transcripts (IL-6, TNF-alpha, and lymphotoxin beta) as well as IL-10 compared with either B7-2 or nontransgenic mice. Hapten-specific IgE was detected by ELISA in B7-1 transgenic mice but not B7-2 transgenic or nontransgenic mice. Only B7-1 transgenic mice exhibited significant immediate type ear swelling responses to the hapten trinitrochlorobenzene. In addition, their sera can passively transfer cutaneous anaphylaxis to naive C57BL/6 mice, indicating that the hapten-specific IgE was relevant to the immediate ear swelling responses. Conclusion These data suggest that keratinocyte-derived costimulation mediated by B7-1 but not B7-2 results in the emergence of T H 2-lymphocyte immune responses to T H 1 haptens. Because human keratinocytes have been noted to express B7-1-like molecules in certain inflammatory skin diseases, this model may be important in understanding the pathophysiology of T H 2-lymphocyte-mediated skin diseases such as atopic dermatitis.

Serum-borne factor(s) of 1,1-dichloroethylene and 1,2-dichlorobenzene-treated mice inhibited in vitro antibody forming cell response and natural killer cell activity.

1,1-Dichloroethylene and 1,2-dichlorobenzene administered to mice produced liver and/or kidney damage which was quantified in this study by a histochemical method. The in vitro effect of sera obtained from these mice on antibody forming cell (AFC) response and natural killer (NK) cell activity was investigated in parallel with the assessment of sera tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels. 1,1-Dichloroethylene (100, 150 and 200 mg/kg) provoked liver and kidney damage. Peak kidney damage occurred 16 h after the dose was administered and at 24 h in the case of the liver. During the peak level of liver damage, a serum-borne immunosuppressive effect was also at its highest level. With respect to sera cytokine levels, an increase of TNF-alpha and IL-6 was detected earlier, i.e. 6 h after toxic administration, followed by a decrease that tended toward a baseline level. There was a relationship between the tissue damage induced by 1,1-dichloroethylene and the immunosuppressive effect of mice sera on AFC response and NK cell activity. 1,2-Dichlorobenzene (300, 500 and 600 mg/kg) provoked only liver damage. Peak liver damage severity was observed 48 h after toxic administration, whereas the highest serum-borne immunosuppressive effect was observed almost immediately, i.e. 6 h after administration. As regards sera cytokine levels, only TNF-alpha could be detected 6 h after administering 500 and 600 mg/kg doses of 1,2 dichlorobenzene. There was a relationship between the liver damage induced by 1,2-dichlorobenzene and the immunosuppressive effect of mice sera on the AFC response. In view of the above results, this study suggests that the immunosuppressive effect in sera of mice treated with 1,1-dichloroethylene and 1,2-dichlorobenzene may result from tissue damage, and that the increased levels of TNF-alpha and IL-6 in sera may contribute to this effect. Further studies are needed to clarify the factor(s) responsible, including transforming growth factor-beta1 (TGF-beta1) causing immunosuppression.

Studies on the contact sensitization of man with simple chemicals. III. Quantitative relationships between specific lymphocyte transformation, skin sensitivity, and lymphokine activity in response to dinitrochlorobenzene.

Dinitrochlorobenzene (DNCB) coupled to peripheral blood erythrocytes or leukocytes forms a particulate complex, DNCB-antigen. The addition of DNCB-antigen induced blastogenesis and DNA synthesis in leukocyte cultures from DNCB-sensitized human subjects and not in leukocyte cultures from nonsensitized controls. In general, sensitized subjects who displayed a higher degree of cutaneous reactivity to DNCB, as manifested by duration and intensity of dermatitis, also showed a greater blastogenic response to DNCB-antigen in vitro. This quantitative correlation, however, was not invariant. Certain soluble factor(s), or lymphokines are released following the addition of DNCB-antigen to leukocyte cultures prepared from some sensitive subjects who were rechallenged one or more times with DNCB. These lymphokines induce blastogenesis in secondary target leukocyte populations from nonsensitized subjects. Extended studies are presented which slow little or no lymphokine activity in peripheral blood leukocyte cultures during a primary immune response, despite high degrees of blastogenic activity in response to DNCB-antigen. Significant lymphokine activity was observed only following additional rechallenge with DNCB. Blastogenesis and skin reactivity specific for DNCB have been shown to develop at about the same time during a primary immune response. This, along with the quantitative correlation shown in this communication, suggests that both processes probably reflect thymic-dependent cellular immunity. The appearance of lymphokine activity following rechallenge with DNCB suggests that DNCB-induced lymphokines may represent an amplifying mechanism of the cellular immune response that involves recruitment of previously uncommitted lymphocytes.

Macrophages activated in vitro with lymphocyte mediators kill neoplastic but not normal cells.

Normal guinea pig macrophages incubated for 3 days in vitro with mediator-rich lymphocyte supernatants become cytotoxic for the syngeneic tumors, line 1 hepatoma and MCA-25 fibrosarcoma. Under identical experimental conditions the survival of two normal syngeneic cell types, fibroblasts and kidney cells, was not affected. The activating supernatants were prepared by stimulating sensitized lymphocyte cultures with an antigen unrelated to the target cells. Therefore, this type of macrophage-mediated cytotoxicity appears to be nonspecific but restricted to cells with malignant growth capacities.

Cellular immunity, peripheral blood lymphocyte count and pathological staging of tumours in the gastrointestinal tract.

The peripheral blood lymphocyte count has been measured in 74 cases of histologically proven carcinoma of the gastrointestinal tract. The count has been correlated with the pathological stage of tumour spread and the patient's delayed hypersensitivity response to 2.4 dinitrochlorobenzene (DNCB). A statistically significant correlation was found between the peripheral blood lymphocyte count and the response to DNCB. There was linear association between the extent of spread of the tumours and the lymphocyte count. Those patients with low peripheral blood lymphocyte counts tended to have more advanced tumours and a poor response to DNCB. The possible causes of this lymphopenia are discussed.