Keyhole Limpet Hemocyanin Challenge Research Articles

Characterization of KLH-driven immune responses in clinical studies: A systematic review

The pharmacological activity assessment of novel immunomodulatory drugs in early-stage drug development is challenging as healthy volunteers do not express relevant immune biomarkers. Alternatively, the immune system can be challenged with keyhole limpet hemocyanin (KLH), a suitable antigen for studying adaptive immune responses. This report systemically reviews the KLH challenge in clinical studies focusing on the characterization of the KLH-driven systemic and local immune responses, identification of the KLH-induced biomarkers, and the evaluation of the effect of pharmacological interventions and diseases on the KLH response. A systematic literature review was carried out in PubMed spanning from 1967 to 2022. The systemic humoral KLH responses could be characterized by ELISA after 3 weeks following immunization. For the systemic cellular and molecular immune responses multiple KLH immunizations and the use of novel techniques such as flow cytometry and ELISpot yield optimal results. The objective evaluation of dermal KLH rechallenge allows for more accurate and sensitive quantification of the local response compared to subjective scoring. For the local cellular and molecular assays after KLH dermal rechallenge we also advocate the use of multiple KLH immunizations. Furthermore, oral KLH feeding, age, physical activity, alcohol consumption, stress, as well as certain auto-immune diseases also play a role in the KLH-induced immune response. Importantly, based on the KLH challenges, the effect of (novel) immunomodulatory drugs could be demonstrated in healthy volunteers, providing valuable information for the clinical development of these compounds. This review underlines the value of KLH challenges in clinical studies, but also the need for standardized and well-controlled methodology to induce and evaluate KLH responses.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifierCRD42022335419

Paraquat Preferentially Induces Apoptosis of Late Stage Effector Lymphocyte and Impairs Memory Immune Response in Mice.

Paraquat (PQ) is a toxic non-selective herbicide. To date, the effect of PQ on memory immune response is still unknown. We investigated the impact of PQ on memory immune response. Adult C57BL/6 mice were subcutaneously injected with 2 mg/kg PQ, 20 mg/kg PQ or vehicle control every three days for two weeks. A single injection of keyhole limpet hemocyanin (KLH) at day four after the initial PQ treatment was used to induce a primary immune response; a second KLH challenge was performed at three months post the first KLH immunization to induce a secondary immune response. In steady state, treatment with 20 mg/kg PQ reduced the level of serum total IgG, but not that of IgM; treatment with 20 mg/kg PQ decreased the number of effector and memory lymphocytes, but not naïve or inactivated lymphocytes. During the primary immune response to KLH, treatment with 20 mg/kg PQ did not influence the proliferation of lymphocytes or expression of co-stimulatory molecules. Instead, treatment with 20 mg/kg PQ increased the apoptosis of lymphocytes at late stage, but not early stage of the primary immune response. During the secondary immune response to KLH, treatment with 20 mg/kg PQ reduced the serum anti-KLH IgG and KLH-responsive CD4 T cells and B cells. Moreover, effector or activated lymphocytes were more sensitive to PQ-induced apoptosis in vitro. Treatment with 2 mg/kg PQ did not impact memory immune response to KLH. Thus, treatment with 20 mg/kg PQ increased apoptosis of late stage effector cells to yield less memory cells and thereafter impair memory immune response, providing a novel understanding of the immunotoxicity of PQ.

Imperfect past and present progressive: beak color reflects early-life and adult exposure to antigen.

Secondary sexual traits may convey information about individual condition. We assessed the capacity for immune challenge with lipopolysaccharide (LPS) or keyhole limpet hemocyanin (KLH) during the prenatal and early postnatal stages to impact beak color development and expression in captive zebra finches. In addition, we tested whether adult immune challenge impacted beak color, and if early-life experience was influential. Immune challenge with KLH early in life slowed development of red beak coloration, and males challenged with KLH as nestlings had reduced red coloration as adults. Following adult KLH challenge, males exhibited a decline in beak redness. Birds challenged with KLH during development produced more anti-KLH antibodies after adult challenge. There was a significant interaction between young treatment and anti-KLH antibody production; for males not challenged with KLH early in life, individuals that mounted a weaker antibody response lost more red coloration after challenge than males mounting a stronger antibody response. Based on models of avian vision, these differences in beak coloration should be detectable to the finches. In contrast to previous studies, we found no effect of early-life or adult challenge with LPS on any aspects of beak coloration. These results provide evidence that beak color reflects developmental and current conditions, and that the signal is linked to critical physiological processes.

Galantamine Attenuates Type 1 Diabetes and Inhibits Anti-Insulin Antibodies in Nonobese Diabetic Mice.

Type 1 diabetes in mice is characterized by autoimmune destruction of insulin-producing pancreatic β-cells. Disease pathogenesis involves invasion of pancreatic islets by immune cells, including macrophages and T cells, and production of antibodies to self-antigens, including insulin. Activation of the inflammatory reflex, the neural circuit that inhibits inflammation, culminates on cholinergic receptor signals on immune cells to attenuate cytokine release and inhibit B-cell antibody production. Here, we show that galantamine, a centrally acting acetylcholinesterase inhibitor and an activator of the inflammatory reflex, attenuates murine experimental type 1 diabetes. Administration of galantamine to animals immunized with keyhole limpet hemocyanin (KLH) significantly suppressed splenocyte release of immunoglobulin G (IgG) and interleukin (IL)-4 and IL-6 during KLH challenge ex vivo. Administration of galantamine beginning at 1 month of age in nonobese diabetic (NOD) mice significantly delayed the onset of hyperglycemia, attenuated immune cell infiltration in pancreatic islets and decreased anti-insulin antibodies in serum. These observations indicate that galantamine attenuates experimental type 1 diabetes in mice and suggest that activation of the inflammatory reflex should be further studied as a potential therapeutic approach.

Selenium Supplementation Restores Innate and Humoral Immune Responses in Footrot-Affected Sheep

Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source (organic Se-yeast, inorganic Na-selenite or Na-selenate) and Se-dosage (1, 3, 5 times FDA-permitted level) on FR severity, 120 ewes with and 120 ewes without FR were drenched weekly for 62 weeks with different Se sources and dosages (30 ewes/treatment group). Innate immunity was evaluated after 62 weeks of supplementation by measuring neutrophil bacterial killing ability. Adaptive immune function was evaluated by immunizing sheep with keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. At baseline, FR-affected ewes had lower whole-blood and serum-Se concentrations; this difference was not observed after Se supplementation. Se supplementation increased neutrophil bacterial killing percentages in FR-affected sheep to percentages observed in supplemented and non-supplemented healthy sheep. Similarly, Se supplementation increased KLH antibody titers in FR-affected sheep to titers observed in healthy sheep. FR-affected sheep demonstrated suppressed cell-mediated immunity at 24 hours after intradermal KLH challenge, although there was no improvement with Se supplementation. We did not consistently prevent nor improve recovery from FR over the 62 week Se-treatment period. In conclusion, Se supplementation does not prevent FR, but does restore innate and humoral immune functions negatively affected by FR.

Toxicologic and immunologic effects of perinatal exposure to the brominated diphenyl ether (BDE) mixture DE‐71 in the Sprague‐Dawley rat

Brominated diphenyl ethers (BDEs) are persistent environmental contaminants found in human blood, tissues, and milk. To assess the impact of the commercial BDE mixture DE-71 on the developing immune system in relation to hepatic and thyroid changes, adult (F0) rats were exposed to DE-71 by gavage at doses of 0, 0.5, 5, or 25 mg/kg body weight (bw)/d for 21 weeks. F0 rats were bred and exposure continued through gestation, lactation and postweaning. F1 pups were weaned and exposed to DE-71 by gavage from postnatal day (PND) 22 to 42. On PND 42, half of the F1 rats were assessed for toxicologic changes. The remaining F1 rats were challenged with the T-dependent antigen keyhole limpet hemocyanin (KLH) and immune function was assessed on PND 56. Dose-dependent increases in total BDE concentrations were detected in the liver and adipose of all F0 and F1 rats. In F0 rats, increased liver weight, hepatocellular hypertrophy, and decreased serum thyroxine (T4) were characteristic of DE-71 exposure. In F1 rats perinatal DE-71 exposure caused a nondose-dependent increase in body weight and dose-dependent increases in liver weight and hepatocellular hypertrophy. Serum T3 and T4 levels were decreased. In spleen from DE-71 exposed rats the area occupied by B cells declined while the area occupied by T cells increased; however, cellular and humoral immune responses to KLH challenge were not altered. Thus hepatic and thyroid changes in rats exposed perinatally to DE-71 were associated with altered splenic lymphocyte populations, an effect which has been linked to hypothyroidism.

Characterization of a murine keyhole limpet hemocyanin (KLH)-delayed-type hypersensitivity (DTH) model: Role for p38 kinase

Molecular and cellular assessment of dermal delayed-type hypersensitivity (DTH) responses is a useful approach for evaluating the mechanism of action (MOA) of immunomodulatory agents. In the present report, we characterized the delayed-type hypersensitivity response induced by keyhole limpet hemocyanin (KLH), and validated its utility by evaluating an immunomodulator, BIRB-796. Intradermal KLH challenge of the ear pinna following subcutaneous antigen sensitization resulted in a pronounced skin inflammation that peaked at 24–48 h. At the molecular level, there was an activation of 3 mitogen-activated protein kinases (MAPKs: p38, JNK and ERK), an induction of the chemokines CCL2/JE, CXCL2/Mip-2, CXCL1/KC, CCL3/Mip-1α CCL4/Mip-1β and CXCL10/IP-10, and expression of the cytokines IL-1β and IL-10 in the ear parenchyma. Modulation of TNFα protein level was only detected in ex-vivo ear whole organ cultures (EWOC). Consistent with this inflammatory profile there was an infiltration of neutrophils and mononuclear cells into the ear parenchyma. BIRB-796, a potent allosteric p38 MAPK inhibitor attenuated the ear swelling response, which correlated with a reduced inflammatory profile. BIRB-796 inhibited p38 but not JNK or ERK kinase activation, decreased multiple chemokines which correlated with a decrease in the infiltration of neutrophils and macrophages; CD4 T cells were modesty reduced. Similarly, there was a decrease of levels of cytokines including IL-1β, IL-10 and TNFα. These data support the utility of this model for evaluating immunomodulators on skin inflammation and suggest that modulation of p38 kinase may be of therapeutic value for the treatment of inflammatory skin conditions.

T helper 2 biased de novo immune response to Keyhole Limpet Hemocyanin in humans

Allergen-specific T helper 2 (Th2) cells play an important role in the pathogenesis of atopic disorders. To date, no model system exists in humans that would allow the monitoring of a developing de novo Th2 immune response in vivo. The aim of the experiment was to establish an immunization protocol inducing a de novo Th2 response in humans using Keyhole Limpet Hemocyanin (KLH) as neo-antigen. The double-blind placebo-controlled, parallel-group study was conducted in two groups of subjects (16 healthy volunteers and 16 patients with allergic rhinitis). Subjects received three i.m. injections of 100 microg KLH adsorbed to aluminium hydroxide or matching placebo (alum alone) in intervals of 2 weeks. On day 43, KLH alone (10 microg) was given intra-dermally (i.d.) to all subjects to assess immediate and late-phase skin responses. The immunization protocol was well tolerated, highly specific and efficient. Antigen-specific production of Th2-cytokines (mainly IL-5 and IL-13) by PBMCs suggested a Th2 pattern, as did the presence of KLH-specific IgG4 in sera. Intra-dermal KLH challenge induced an immediate-type of response predominantly in atopic subjects followed by a late-phase skin reaction. The latter was accompanied by the presence of IgE(+) cells, eosinophils and a strong up-regulation of IL-4 and IL-13 along with the absence of Th1 transcripts in biopsies taken from the site of antigen challenge. IL-17 and IL-22 transcripts were detected only in healthy subjects skin following KLH challenge, while IL-1beta and IL-33 expression did not differ between the healthy and the atopics. The immunization protocol resulted in the elicitation of a local and peripheral Th2 immune response in both healthy and atopic individuals. This may permit the investigation and monitoring of novel immunomodulatory strategies aiming to interfere with Th2 responses in man. The relevance of lack of Th17 cells in atopic skin in this model remains to be determined.

Neonatal bacterial endotoxin challenge interacts with stress in the adult male rat to modify KLH specific antibody production but not KLH stimulated ex vivo cytokine release

While postnatal bacterial infection is capable of inducing a variety of long lasting functional alterations in immune function, the specific physiological pathways responsible for this modification are largely unknown. In the current investigation we explore the hypothesis that early life exposure to endotoxin permanently modifies the function of T helper (Th) cell activity. Therefore we examined Th-cell regulated in vivo humoral and ex vivo cellular responses to keyhole limpet hemocyanin (KLH). Given that stress has been shown to exacerbate some of the immunological alterations exhibited by the neonatally endotoxin challenged adult, we examined the adult's Th1/Th2 responses to KLH under conditions of no stress, acute stress (2 days × 2 h), and chronic stress (7 days × 2 h). Our results demonstrate that adults neonatally challenged with endotoxin were found to produce significantly less IgG1 following KLH challenge following acute stress ( p < 0.05). Neonatally endotoxin treated animals exposed to acute stress were also found to produce less IgM than saline or endotoxin treated animals exposed to no-stress or chronic stress. No neonatal treatment group differences observed in the production of INF-γ or IL-4 in adulthood. In summary, the results from the present study provide little evidence to directly support the hypothesis that neonatal endotoxin exposure significantly alters the Th1/Th2 balance in adulthood.

Proinflammatory cytokine expression in the endolymphatic sac during inner ear inflammation.

The inner ear is capable of rapidly mounting an immune response that can ultimately lead to cochlear degeneration and permanent hearing loss. The role of the endolymphatic sac in this immune process is not clear. In order to investigate the cytokine expression of cells within the endolymphatic sac, a secondary inner ear immune response to keyhole limpet hemocyanin (KLH) was created in mice. The animals were sacrificed 3-48 h and 7 days following initiation of the immune response. The cochleas and endolymphatic sacs were assayed by immunocytochemistry for IL-1beta, TNFalpha, and IL-6. Three hours after KLH challenge of the scala tympani, the perisaccular tissue of the endolymphatic sac contained more inflammatory cells than the scala tympani or endolymphatic sac lumen. Only a few of these cells, however, expressed the proinflammatory cytokines IL-1beta and TNFalpha between 3 and 12 h after KLH injection. On the other hand, TNFalpha, which plays an important role in the cochlear secondary immune response, was expressed in cells in the endolymphatic sac lumen. The maximum percentage of cells expressing TNFalpha was seen later than in the scala tympani. Animals treated with systemic injection of the TNF blocker, etanercept, showed a reduction in the number of cells in the endolymphatic sac lumen. It is concluded that the cells in the endolymphatic sac lumen contribute to the amplification of the adaptive immune response by expressing TNFalpha, while the infiltration of cells into the perisaccular connective tissue is part of the nonspecific, innate, cochlear immune response.

Immune responsiveness in renal transplant recipients: Mycophenolic acid severely depresses humoral immunity in vivo

Current immunosuppressive drug treatments for renal transplant recipients result in high one-year graft survival rates. Despite adequate suppression of the immune response directed to the allograft, the immune system remains able to cope with many infectious agents. To define the influence of distinct immunosuppressive treatment protocols, primary and secondary cellular and humoral immune responses in groups of renal transplant recipients were studied: patient treated with prednisolone and cyclosporine A (P/CsA); with IgA CD3 monoclonal antibody as a rejection treatment superimposed on prednisolone and cyclosporine A (IgA CD3 mAb+P/CsA); and with prednisolone, cyclosporine A and mycophenolate mofetil (P/CsA/MMF). Primary in vitro proliferative responses to the protein antigen keyhole limpet hemocyanin (KLH) were not significantly disturbed in P/CsA treated patients, or in IgA CD3 mAb+P/CsA and P/CsA/MMF treated patients. In vitro proliferative responses to the recall antigen tetanus toxoid (TT) were similarly unaffected. Antigen-specific antibody responses to immunization with KLH and TT were not affected by treatment with P/CsA, or by IgA CD3 mAb+P/CsA, but were severely disturbed in patients treated with P/CsA/MMF. All patients displayed a profound inhibition of the delayed-type hypersensitivity skin reactivity to KLH and recall antigens. Nevertheless, in most patients with P/CsA treatment, T cell infiltrates were observed in skin biopsies from the site of KLH challenge, while expression of intercellular cell adhesion molecule-1 (ICAM-1) expression in challenged skin was significantly decreased in these patients. The balance between T helper 1 and T helper 2 cells was unaffected by immunosuppressive treatments during one year of follow-up. Immunosuppressive drug treatment with P/CsA inhibits delayed-type hypersensitivity skin reactions to both primary and frequently encountered antigens. Histological studies indicate an effect on ICAM-1 expression, leaving the influx of CD3pos T cells unaffected. Administration of a 10-day course of IgA CD3 mAb does not add profound immunosuppressive effects on the measured parameters. In contrast, addition of treatment with MMF profoundly decreases both primary and secondary humoral immune responsiveness in vivo. Finally, no effect of the studied immunosuppressive drugs on Th1/Th2 balance in vivo was measured.

DEVELOPMENTAL IMMUNOTOXICOLOGY ASSESSMENT IN THE RAT: AGE, GENDER, AND STRAIN COMPARISONS AFTER EXPOSURE TO LEAD

A delayed-type hypersensitivity response (DTH) measured against keyhole limpet hemocyanin (KLH) and an enzyme-linked immunosorbant assay (ELISA) for anti-KLH IgG antibody were studied for potential use as biomarkers for the assessment of immunotoxicity after exposure to a xenobiotic during fetal development. Age, gender, site of antigenic challenge, and strain of rat were used as variables. The heavy metal lead was used because it is a known developmental immunotoxin. In the age comparison, untreated juvenile (5-week-old) SpragueDawley (CD) rats produced lower levels of antibody and showed a smaller DTH response than adults; only adult males had a statistically significant increase in the DTH response. Both male and female adults showed a statistically significant increase in levels of antibody over those of both genders of weanlings. As to site of KLH challenge, the DTH response was greater in untreated young animals when they were challenged in the footpad rather than the earlobe. Gender differences in ...

Antigen removal after inoculation into the endolymphatic sac of immunized guinea pigs

Antigen removal in the endolymphatic sac (ES) was immunohistochemically examined. Forty-five adult female Hartley guinea pigs were used in this study. After keyhole limpet hemocyanin (KLH) systemic immunization, KLH was directly injected into the lumen of the right ES. The presence of KLH was detected in histological sections using immunohistochemistry. After KLH challenge into endolymphatic sac lumen, high concentrations of KLH were diffusely found within phagocytes in the endolymphatic lumen and peri-saccular tissue on day 2. After day 14, KLH disappeared from the immunized inner ear. The above results suggest that KLH is removed from the inner ear by diffusion through the endolymphatic epithelial cells which have altered permeability or by phagocytosis of the phagocytic cells. No KLH was observed in the left endolymphatic sac and bilateral cochlea as well as vestibular organ during 5 months of follow up. This study showed that the endolymphatic sac is capable of appropriately trapping macromolecule, KLH antigen (molecular weight: about 400 KDa), and removing antigens quickly from the inner ear.

Antigen-specific immune responsiveness and lymphocyte recruitment in leukocyte adhesion deficiency type II.

The leukocyte adhesion deficiency syndrome type II (LAD-II) is caused by a general defect in fucose metabolism, which leads to the absence of fucosylated sugar determinants such as the selectin ligand SLe(x). In view of the important role of selectins in lymphocyte migration and homing, we have explored the in vivo immune responsiveness and lymphocyte recruitment to the skin, in response to the neo-antigen keyhole limpet hemocyanin (KLH) in a LAD-II patient. We observed a normal priming of KLH-specific T cells as well as a strong in vivo anti-KLH antibody response, both indicative of a normal T-B cell function and collaboration. Skin biopsies from the patient's skin taken prior to antigenic challenge showed the presence of normal numbers and subsets of T cells. Upon KLH injection, a large number of T cells were found to be recruited to the site of challenge, which was paralleled by up-regulation of the endothelial adhesion molecules ICAM-1 (CD54), VCAM-1 (CD106) and E-selectin (CD62E). The recruited T cell showed a normal subset distribution but lacked cutaneous lymphocyte antigen (CLA), the cutaneous homing receptor. However, the clinical symptoms of delayed-type hypersensitivity in the patient (redness and swelling) were severely depressed compared to that in the controls. In conclusion, the LAD-II patient showed a normal T cell priming and T cell-dependent antibody response, a normal baseline skin homing, and a significant T cell recruitment to the site of KLH challenge, indicating that fucosylated sugar determinants such as SLe(x) and CLA are not strictly required for adequate immune responsiveness and (skin) homing.

Alterations in the distributions of the basement membrane components after secondary inner ear immune reaction in guinea pigs

Alterations in the distributions of type IV collagen (C-IV), laminin (La), and fibronectin (Fib), which are important components of the basement membrane, in the inner ear following secondary endolymphatic sac immune response were studied immunohistologically using control animals for comparison. Endolymphatic hydrops developed following direct secondary keyhole limpet hemocyanin (KLH) challenge to the endolymphatic sac in systematically pre-sensitized animals. In the endolymphatic sacs of control animals, C-IV and La were localized continuously just under epithelial cells whereas Fib was present intermittently in subepithelial connective tissue. In the endolymphatic sac, following secondary KLH challenge, linear subepithelial localizations of C-IV and La were interrupted, thinner and more loosely aggregated with numerous inflammatory cellular infiltrates on days 2-4. Following these changes, endolymphatic hydrops in the cochlea developed and peaked on days 4-7. On days 1-7, Fib was strongly but sporadically localized in subepithelial cells. These results suggest that C-IV and La may play important roles in the regulation of endolymph whereas Fib may be related to the restoration of injured endolymphatic sac tissue in animals exposed to a secondary challenge.

Immunological approach to Ménière's disease: vestibular immune injury following immune reaction of the endolymphatic sac.

Following direct antigen challenge to the endolymphatic sac (sac), the relation of caloric test results and spontaneous nystagmus to the histological changes of the sensory epithelium of the vestibular organ and perilymph antibody levels was investigated in the guinea pig. In a secondary keyhole limpet hemocyanin (KLH) challenge to the sac, irritative nystagmus was followed by paralytic nystagmus and a suppression of caloric reaction. These findings correlated well with the degree of degeneration of the sensory epithelium of the vestibular organ and the levels of perilymph antibody. On the other hand, neither phosphate-buffered saline inoculation nor primary KLH challenge to the sac nor a secondary KLH challenge to the intradural space resulted in a disturbance of the vestibular function. These results suggest that the immune response of the sac may possibly be an important key to the pathogenesis of Ménière's disease.

Secretory component and IgA in the endolymphatic sac.

Immunohistochemical methods were used to investigate secretory component (SC) and immunoglobulin A within the inner ears of Sprague Dawley rats and BALB/c mice. Utilizing specific antisera against SC and IgA, the distribution and localization of SC and IgA were studied in normal, non-immunized ears of both animal species. The kinetics of SC and IgA were also investigated during a secondary immune response following keyhole limpet hemocyanin (KLH) challenge of murine inner ears. In the non-immunized murine inner ear, neither SC or IgA were found. In contrast, SC was localized within the epithelial cells and lumen of the endolymphatic sac (ES) in non-immunized rats and faint luminal IgA staining was seen in one-third of the animals, as well as an occasional IgA-bearing cell in the ES. In the inner ear secondary immune response, SC was found only within the endolymphatic sac of approximately 50% of the immunized mice 14 days after KLH challenge. IgA-bearing cells were also observed within the ES 2 to 3 weeks following KLH challenge. We conclude that there are species differences in the distribution of SC and IgA within the inner ear, and that under pathological conditions the endolymphatic sac may be a site of IgA and SC induction.

Lymphocyte subsets in immune-mediated otitis media with effusion.

To examine the role of T-cell subsets in immune-mediated otitis media with effusion induced by keyhole limpet hemocyanin (KLH), we used immunohistochemical methods to investigate the kinetics of immunocytes of the middle ear (ME) and eustachian tube (ET) in healthy BALB/c mice. Antibodies against murine macrophages and granulocytes (anti-Mac-1), helper T cells (anti-Lyt-1), suppressor T cells (anti-Lyt-2), immunoglobulins (anti-IgG, -IgM, -IgA), secretory component (SC) and KLH were used. The ME exhibited a substantial immune response, whereas the response of the ET was minor and was associated with a secondary ME immune response. After KLH challenge, an effusion with an extensive infiltration of inflammatory cells (Mac-1, IgG+ and IgM+ cells) was observed at days 1 and 3 in the ME cavity and rapidly disappeared by day 7. Within the ME mucosa, a large number of cells was observed at days 1 and 3, peaking on day 7 when a submucosal lymphoid infiltration was detected. In the immune response of the ME mucosa, Mac-1 cells were the predominant cell type followed by helper T cells, IgG+ cells, IgA+ cells and then IgM+ cells. Suppressor T cells were rarely detected after KLH challenge. SC was present within ME epithelial cells from days 1 to 14.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of endolymphatic hydrops following immune response in the endolymphatic sac of the guinea pig.

The present study investigated immune injury associated with endolymphatic hydrops (e.hydrops) following locally mounted immune reaction in the endolymphatic sac (e.sac) of guinea pigs. E.hydrops occurred, progressing rapidly within the first week post secondary Keyhole limpet hemocyanin (KLH) challenge in the e.sac and developed into two phases, acute and chronic. On the other hand, primary KLH challenge of the e.sac, PBS inoculation into the e.sac or intradural secondary KLH challenge were incapable of inducing e.hydrops. These results indicate that reversible and irreversible e.hydrops are induced by the immune response of the e.sac, suggesting that local immunological events of the e.sac may provide an animal model of Meniere's disease.

Immuno-injury to the inner ear auditory system following secondary endolymphatic sac immune response

This study investigated immuno-injury to the inner ear auditory system following inner ear immune response in the guinea pig. The endolymphatic sac (ES) was directly challenged with keyhole limpet hemocyanin (KLH). Auditory brainstem response with click sound stimulation was assessed pre and post KLH challenge of the ES. In systematically presensitized animals, secondary KLH challenge to the ES produced significant elevation of the mean threshold level on day 3 and 17 as compared to that of pre challenge levels. However, no significant prolongation of the latency (N1-N3) was observed. On the other hand, neither phosphate buffered saline injection into the ES nor primary KLH challenges of the ES were capable of elevating the threshold level and changing the latency. These results indicate that elevation of threshold was apparently induced by a secondary immune response of the ES, not by nonspecific mechanical damage to the ES, the central auditory system or KLH toxicity to the inner ear, suggesting that local immune response of the ES is a possible pathogenesis of sensorineural hearing loss.