Immunohistology of human allergic late-phase skin reactions

Immunohistological analysis of peptide-induced delayed-type hypersensitivity in advanced melanoma patients treated with melanoma antigen-pulsed mature monocyte-derived dendritic cell vaccination

BACKGROUND

In melanoma patients vaccinated with monocyte-derived melanoma peptide-pulsed dendritic cells (DC), the delayed-type hypersensitivity (DTH) reactions have been examined as a surrogate marker to determine if acquired immunity is induced by DC vaccination. To date, however, only limited information has been reported as for histopathological analyses of DTH.

OBJECTIVE

To evaluate tumor-specific immunomonitoring histopathologically after DC vaccination in melanoma patients.

METHODS

Seven patients previously vaccinated with monocyte-derived melanoma peptide-pulsed DCs were challenged with recall antigenic peptide injection in the skin of the forearm. Using immunohistochemical techniques, the presence of immune cells and the expression of CD4, CD8, interleukin (IL)-2, IL-4, IL-10, Foxp3, CD1a, CD1d, and interferon (IFN)-gamma was investigated at the site of injection where a DTH reaction developed.

RESULTS

Strong DTH reactions from infiltrated erythema to bullae formation were detected in all 7 cases. Biopsies taken from the DTH site revealed heavy infiltration of mononuclear cells and eosinophils in the dermis and subcutaneous tissue. Cells staining positively for CD4, CD8, IL-2, IL-4, Foxp3, CD1d, and IFN-gamma were increased at the site 48h after antigen injection in all cases. Cells positive for IL-10 were never found in any patient. Regulatory T cells appeared 6h after injection and reached their maximum at day 7.

CONCLUSIONS

The significant induction of CD8(+)T cells as well as both Th1 and Th2-type cells at the site of DTH suggests that effective antigen presentation leading to anti-tumor immune responses has taken place. Inhibitory mechanisms may also develop as the disappearance of the DTH response could be related to an increase in Foxp3+ cells.

A novel artemisinin derivative, 3-(12-beta-artemisininoxy) phenoxyl succinic acid (SM735), mediates immunosuppressive effects in vitro and in vivo

AIM

To study the immunosuppressive activity of SM735 {[3-(12-beta-artemisininoxy)] phenoxyl succinic acid}, a synthetic artemisinin derivative with nonsteroidal anti-inflammatory drug structure, with the aim of finding potential immunosuppressive agents.

METHODS

Concanavalin A (ConA), lipopolysaccharide (LPS), and mixed lymphocyte reaction (MLR), were used to induce the proliferation of splenocytes, and [3H]-thymidine incorporation was used to evaluate the proliferation of splenocytes. Cytokine production was promoted with ConA, LPS, or PMA plus ionomycin, and was detected with the enzyme-linked immunosorbent assay. Dinitrofluorobenzene (DNFB) and sheep red blood cells (SRBC) were used to induce delayed-type hypersensitivity and quantitative hemolysis of SRBC (QHS) mouse models, as criteria for the evaluation of in vivo immune activity.

RESULTS

SM735 strongly inhibited the proliferation of splenocytes induced by ConA, LPS, or MLR, with IC(50) values of 0.33 micromol/L, 0.27 micromol/L, and 0.51 micromol/L, respectively. When compared with a CC(50) value of 53.1 micromol/L, SM735 had a favorable safety range. SM735 dose-dependently inhibited proinflammatory cytokine production [including interleukins (IL)-12, interferon (IFN)-gamma and IL-6] induced by LPS or PMA plus ionomycin. Upon ConA stimulation, SM735 suppressed IFN-gamma in a dose-dependent manner, but did not affect IL-2 secretion. SM735 also strongly suppressed both T-cell-mediated delayed-type hypersensitivity (DTH) and B-cell-mediated QHS reactions.

CONCLUSION

SM735 had strong immunosuppressive activity in vitro and in vivo, suggesting a potential role for SM735 as an immunosuppressive agent, and established the groundwork for further research on SM735.

Characterization of the inflammatory infiltrate during IgE-mediated late phase reactions in the skin of normal and atopic dogs

In canine and human atopic patients, the intracutaneous injection of offending allergens is followed by the development of both immediate and late-phase reactions. The present study was performed to expand on the characterization and dynamics of inflammatory cell subsets during IgE-mediated late-phase reactions in canine skin. Three normal dogs and three Dermatophagoides farinae-allergic dogs were selected for this experiment. All dogs were challenged intradermally with mite allergen, purified anticanine IgE antibodies (positive control) or phosphate-buffered saline (negative control). Skin biopsies were obtained before and 6, 12 and 24 h post-injection. Sections were stained with metachromatic and eosinophil-specific histological stains. Additionally, we used an immunohistochemical method with antibodies specific for canine leukocyte antigens. This study confirmed the occurrence of a late-phase reaction in atopic skin following allergen challenge, and in normal and atopic canine skin after intradermal injection of IgE-specific antibodies. Whereas early emigrating dermal cells were composed chiefly of neutrophil and activated eosinophil granulocytes, there was an influx of alpha beta T-lymphocytes and dermal dendritic cells in later stages of the late-phase reactions. Because IgE-mediated late-phase reactions resemble spontaneous atopic canine skin lesions, both at macroscopic and microscopic levels, we propose the use of similar challenges to study the anti-inflammatory effects of anti-allergic drugs in a pre-clinical setting.

Temporal patterns of mediator release during developing cutaneous late-phase reactions

BACKGROUND

Several inflammatory mediators have been found released in sites of cutaneous late phase reactions (LPR). However, the temporal pattern of their release during LPR development has not been characterized.

OBJECTIVE

Determine hourly accumulation of mediator release in comparison with gross and inflammatory cell responses during developing LPR.

METHODS

Skin chamber appended to sites of allergen and diluent control challenge with hourly collections. Then, study of exuding leucocytes in chamber bases.

RESULTS

In the allergen-challenged sites, histamine release peaked in the first hour, then low level release over the next 5 h. Lactoferrin release from neutrophils started by the second hour, likely associated with released IL-8. Eosinophil cationic protein levels started increasing slightly later. The percentage of exuding leucocytes which were activated was significantly higher in the allergen challenge sites than in the control challenge sites

CONCLUSIONS

Both gross LPR and local inflammatory cell responses in the skin start soon after the immediate mast cell activation in IgE-mediated responses. Such inflammatory responses include leucocyte activation and mediator release.

Sequential patterns of inflammatory events during developing and expressed skin late-phase reactions

BACKGROUND

Although there has been much study of the histologic features of the late-phase reactions (LPR) seen 6 to 24 hours after intradermal injection of allergens, much less is known about the events occurring during development of such LPR.

OBJECTIVE

Our purpose was to compare sequential gross and histologic inflammatory responses during developing skin LPR within 6 hours after challenge.

METHODS

Gross reactions were measured and biopsy specimens obtained at 20 minutes and 1, 2, and 6 hours after intradermal allergen (Ag) and buffer diluent control (B) injections in 7 atopic subjects with known immediate and LPR. Inflammatory cell responses were compared, as detected by immunohistochemistry in Ag and B sites. These findings were then compared with those at 24 hours.

RESULTS

Gross LPR evolved without a hiatus from the immediate wheal responses over the next 6 hours (P =.04 vs that in B sites) and then decreased by 24 hours. Prominent PMN accumulation started by 20 minutes, peaking at 1 hour (P <.01). Eosinophil accumulation was significant, starting at 1 hour (P <.001) and peaking at 6 hours (P < .001). Many eosinophils were activated (EG(2)(+)). T-cell accumulation started at 2 hours (P =.01) and was most prominent at 24 hours. The frequency of vessels expressing E-selectin increased at 1 hour (P <.005), correlating with the degree of local PMN accumulation. The frequency of vessels expressing vascular cell adhesion molecules started increasing at 6 hours (P = .02), well after eosinophil accumulation was prominent.

CONCLUSIONS

Skin LPR is characterized by evolution of a gross indurated reaction from the immediate whealing response over the first 6 hours after intradermal Ag challenge, with an early accumulation of PMN and eosinophils, not directly attributable to lymphocyte entry or vascular cell adhesion molecule expression. Likely, multiple other factors may also play roles in the complex pathogenesis of LPR.

Characterization of the cutaneous inflammatory infiltrate in canine atopic dermatitis

Sections from lesional atopic, clinically normal atopic, and normal canine skin were investigated by light microscopy and an immunoperoxidase method using monoclonal antibodies specific for canine leukocyte antigens. We confirmed that skin-infiltrating cells of canine atopic dermatitis are constituted of mast cells, dendritic antigen-presenting cells, memory helper T-lymphocytes, low numbers of eosinophils and neutrophils, and rare B-lymphocytes. The presence of epidermal eosinophil microaggregates and clustered Langerhans' cells supports the hypothesis of epidermal allergen contact. The hyperplasia of epidermal T-cells expressing the gamma/delta T-cell receptor appears specific to canine atopic dermatitis compared with its human counterpart. This finding could be explained by an interspecies difference in skin immune systems or, alternatively, by an active participation of these epitheliotropic gamma/delta T-cells in the cutaneous allergic immune response in dogs. The paucity of dermal neutrophils in spontaneous lesions of canine atopic dermatitis is notably different from the neutrophil-rich late-phase reactions provoked by intradermal allergen injections in allergic dogs. This difference in the cellular infiltrate probably results from variations in the immune reaction between single and repeated allergen exposure as well as epidermal versus dermal antigen contact.

Experimental bystander encephalitis induced by immunization with HTLV-I-producing T cells in mice

ICR mice were immunized with HTLV-I carrier T lymphocytes (MT-2 cell line) and then inoculated intracerebrally with these cells. After non-specific traumatic hemorrhage, perivascular cell infiltration was noted diffusely throughout the brain on day 2 and lasted for over 2 weeks. HTLV-I antigens were detected in both sides of the cerebral hemisphere by Western blotting analysis. Tissue damage consisting of demyelination, axonal degeneration, and astrogliosis was observed most heavily on days 10 and 14. Non-immunized mice inoculated with the cells showed only transient hemorrhage. In cases using the HTLV-I free T-cell line (MOLT-4) inflammatory cell infiltration and tissue damage was much less conspicuous and disappeared after day 10. These experiments support the hypothesis that HAM/TSP is a bystander disease initiated and progresses via HTLV-I-infected T-cell invasion into the spinal cord of a patient who has been infected and sensitized to the virus.

The role of eosinophils in the pathogenesis of atopic dermatitis--eosinophil granule proteins as markers of disease activity

Currently, there is a large body of evidence that atopic dermatitis (AD) has an immunologic basis. Atopy-specific helper T cells (Th2-like T cells) may play a pathogenetic role by producing and releasing cytokines relevant for the allergic inflammation, such as IL-4, IL-5, and other growth factors. Eosinophils are believed to be of major importance as effector cells mediating the pathogenetically relevant late-phase reaction which is associated with a significant destruction of the surrounding tissue. Accordingly, a significant preactivation of peripheral blood eosinophils was detected in AD patients, leading to an enhanced susceptibility of these cells to distinct stimuli such as IL-5. Toxic proteins, such as eosinophil cationic protein (ECP), contained in the matrix and the core of secondary granules of eosinophils, may play an important role by propagating the allergic inflammatory process and by modulating the immune response. The pathogenetic role of eosinophils in AD is further supported by the detection of these proteins in the eczematous skin of patients. Furthermore, recent data point to a significant correlation between disease activity and deposition of eosinophil granule content: ECP serum levels were significantly increased in AD patients. In addition, ECP levels correlated with the disease activity. Moreover, clinical improvement was associated with a decrease of both the clinical score and serum ECP levels. These data clearly indicate that activated eosinophils may play a major role in the allergic inflammatory process of AD. Therefore, modulation of eosinophil activation could prove to be an important pharmacologic modality for the treatment of AD.