Detection of human cytokines in situ using antibody and probe based methods

A novel dendritic cell-based direct ex vivo assay for detection and enumeration of circulating antigen-specific human T cells

Although a variety of assays have been used to examine T cell responses in vitro, standardized ex vivo detection of antigen-specific CD4⁺ T cells from human circulatory PBMCs remains constrained by low-dimensional characterization outputs and the need for polyclonal, mitogen-induced expansion methods to generate detectable response signals. To overcome these limitations, we developed a novel methodology utilizing antigen-pulsed autologous human dendritic target cells in a rapid and sensitive assay to accurately enumerate antigen-specific CD4⁺ T cell precursor frequency by multiparametric flow cytometry. With this approach, we demonstrate the ability to reproducibly quantitate poly-functional T cell responses following both primary and recall antigenic stimulation. Furthermore, this approach enables more comprehensive phenotypic profiling of circulating antigen-specific CD4⁺ T cells, providing valuable insights into the pre-existing polarization of antigen-specific T cells in humans. Combined, this approach permits sensitive and detailed ex vivo detection of antigen-specific CD4⁺ T cells delivering an important tool for advancing vaccine, immune-oncology and other therapeutic studies.

Plasma and bronchoalveolar lavage samples in acute lung allograft rejection: the potential role of cytokines as diagnostic markers

The role of differential cytology patterns in peripheral blood and bronchoalveolar lavage samples is increasingly investigated as a potential adjunct to diagnose acute and chronic allograft dysfunction after lung transplantation. While these profiles might facilitate the diagnosis of acute cellular rejection, low sensitivity and specificity of these patterns limit direct translation in a clinical setting. In this context, the identification of other biomarkers is needed. This review article gives an overview of cytokine profiles of plasma and bronchoalveolar lavage samples during acute cellular rejection. The value of these cytokines in supporting the diagnosis of acute cellular rejection is discussed. Current findings on the topic are highlighted and experimental settings for future research projects are identified.

Interleukin-2 expression in lupoid and usual types of old world cutaneous leishmaniasis

Background:

Interleukin (IL)-2 plays a central role in T cell-dependent immune responses.

Objectives:

We conducted this study to determine and compare IL-2 expression in lupoid and usual types of Old World Cutaneous Leishmaniasis (OWCL), using immunohistochemistry.

Patients and Methods:

Thirteen paraffin-embedded specimens of lupoid and 12 specimens of usual types of OWCL were used. A mouse monoclonal anti IL-2 antibody was used for staining by the envision technique.

Results:

There were strongly stained discrete foci of staining through inflammatory infiltrates of dermis and also in basal layers of epidermis and adnexal structures, with a distinctive pattern of hot spot activity foci (mean of 9.31 ± 6.4 versus 8.17 ± 6.9 foci per HPF for lupoid and usual types, respectively). The expression of IL-2 had no correlation with the pattern of granulomatous inflammation (tuberculoid, sarcoidal or mixed suppurative).

Conclusions:

Interleukin-2 takes part in the immunological response of the granulomatous reaction of OWCL and is not statistically different between lupoid and usual types (P = 0.674).

Label-free microcavity biosensors: steps towards personalized medicine

Personalized medicine has the potential to improve our ability to maintain health and treat disease, while ameliorating continuously rising healthcare costs. Translation of basic research findings to clinical applications within regulatory compliance is required for personalized medicine to become the new foundation for practice of medicine. Deploying even a few of the thousands of potential diagnostic biomarkers identified each year as part of personalized treatment workflows requires clinically efficient biosensor technologies to monitor multiple biomarkers in patients in real time. This paper discusses a critical component of a regulatory system, a microcavity optical biosensor for label-free monitoring of biomolecular interactions at physiologically-relevant concentrations. While most current biosensor research focuses on improving sensitivity, this paper emphasizes other characteristics a biosensor technology requires to be practical in a clinical setting, presenting robust microcavity biosensors which are easy to manufacture and integrate with microfluidics into flexible and redesignable platforms making the microcavity biosensors deployable for continuous monitoring of biomarkers in body fluids in the clinic, in dense 2D random arrays for high-throughput applications like drug-library screening in interactomics, and of the secretory behavior of single cells in the laboratory.

Pleural tuberculosis in patients with early HIV infection is associated with increased TNF-alpha expression and necrosis in granulomas

Although granulomas may be an essential host response against persistent antigens, they are also associated with immunopathology. We investigated whether HIV co-infection affects histopathological appearance and cytokine profiles of pleural granulomas in patients with active pleural tuberculosis (TB). Granulomas were investigated in pleural biopsies from HIV positive and negative TB pleuritis patients. Granulomas were characterised as necrotic or non-necrotic, graded histologically and investigated for the mRNA expression of IL-12, IFN-gamma, TNF-alpha and IL-4 by in situ hybridisation. In all TB patients a mixed Th1/Th2 profile was noted. Necrotic granulomas were more evident in HIV positive patients with a clear association between TNF-alpha and necrosis. This study demonstrates immune dysregulation which may include TNF-alpha-mediated immunopathology at the site of disease in HIV infected pleural TB patients.

Increased plasma macrophage inflammatory protein (MIP)-1α and MIP-1β levels in type 1 Gaucher disease

Pancytopenia, hepatosplenomegaly and skeletal complications are hallmarks of Gaucher disease. Monitoring of the outcome of therapy on skeletal status of Gaucher patients is problematic since currently available imaging techniques are expensive and not widely accessible. The availability of a blood test that relates to skeletal manifestations would be very valuable. We here report that macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, both implicated in skeletal complications in multiple myeloma (MM), are significantly elevated in plasma of Gaucher patients. Plasma MIP-1alpha of patients (median 78 pg/ml, range 21-550 pg/ml, n=48) is elevated (normal median 9 pg/ml, range 0-208 pg/ml, n=39). Plasma MIP-1beta of patients (median 201 pg/ml, range 59-647 pg/ml, n=49) is even more pronouncedly increased (normal median 17 pg/ml, range 1-41 pg/ml, n=39; one outlier: 122 pg/ml). The increase in plasma MIP-1beta levels of Gaucher patients is associated with skeletal disease. The plasma levels of both chemokines decrease upon effective therapy. Lack of reduction of plasma MIP-1beta below 85 pg/ml during 5 years of therapy was observed in patients with ongoing skeletal disease. In conclusion, MIP-1alpha and MIP-1beta are elevated in plasma of Gaucher patients and remaining high levels of MIP-1beta during therapy seem associated with ongoing skeletal disease.

Selective retention of herpes simplex virus-specific T cells in latently infected human trigeminal ganglia

Primary infection with herpes simplex virus 1 (HSV-1) and varicella zoster virus (VZV) results in lifelong latent infections of neurons in sensory ganglia such as the trigeminal ganglia (TG). It has been postulated that T cells retained in TG inhibit reactivation of latent virus. The acquisition of TG specimens of individuals within hours after death offered the unique opportunity to characterize the phenotype and specificity of TG-resident T cells in humans. High numbers of activated CD8(+) T cells expressing a late effector memory phenotype were found to reside in latently infected TG. The T cell infiltrate was oligoclonal, and T cells selectively clustered around HSV-1 but not VZV latently infected neurons. Neuronal damage was not observed despite granzyme B expression by the neuron-interacting CD8(+) T cells. The TG-resident T cells, mainly CD8(+) T cells, were directed against HSV-1 and not to VZV, despite neuronal expression of VZV proteins. The results implicate that herpesvirus latency in human TG is associated with a local, persistent T cell response, comprising activated late effector memory CD8(+) T cells that appear to control HSV-1 latency by noncytolytic pathways. In contrast, T cells do not seem to be directly involved in controlling VZV latency in human TG.

Myelin-laden macrophages are anti-inflammatory, consistent with foam cells in multiple sclerosis

Multiple sclerosis lesion activity concurs with the extent of inflammation, demyelination and axonal suffering. Pro-inflammatory myeloid cells contribute to lesion development, but the self-limiting nature of lesions implies as yet unidentified anti-inflammatory mechanisms. We addressed the hypothesis that myelin ingestion by myeloid cells induces a foamy appearance and confers anti-inflammatory function. First, we show that myelin-containing foam cells in multiple sclerosis lesions consistently express a series of anti-inflammatory molecules while lacking pro-inflammatory cytokines. Second, unique location-dependent cytokine and membrane receptor expression profiles imply functional specialization allowing for differential responses to micro-environmental cues. A novel human in vitro model of foamy macrophages functionally confirmed that myelin ingestion induces an anti-inflammatory programme. Foamy macrophages are unable to respond to prototypical inflammatory stimuli but do express molecules involved in suppression of inflammation. These findings provide novel insights into the mechanisms of lesion control and may open new roads to intervention.

Optimum culture conditions for specific and nonspecific activation of whole blood and PBMC for intracellular cytokine assessment by flow cytometry

The assessment of cytokine production is an important component of studies of cell-mediated immune responses (CMI) to immunological challenges. In this study, we present a method to enhance the detection of cytokine-producing cells by allowing antigen-specific cells to expand in long-term culture. We investigated the influence of the degree of dilution of whole blood and the duration of the incubation period on whole blood as well as peripheral blood mononuclear cells (PBMCs), cultured in the absence or presence of mitogens, superantigens or specific antigens, for intracellular cytokine production (IFNgamma, TNFalpha, IL-2, IL-4, IL-10 and IL-13) by CD4+ and CD8+ T lymphocytes using four-colour flow cytometry. Whole blood was diluted 1/1, 1/2, 1/5 and 1/10, and cultured for 6, 24, 48, 72 and 120 h in the presence of antibodies against the co-stimulatory molecules CD28 and CD49d, and, during the last 4 h of culture, in the presence of brefeldin A. Optimum conditions for detection of a high number of IFNgamma-positive cells were observed after 72 h of culture in blood diluted 1/10. Median frequencies of IFNgamma+ cells obtained after activation by PMA-ionomycin, PHA or SEA-B were 29.3%, 20.0% and 6.8% for CD4+ cells, and 67.8%, 20.6% and 6.8% for CD8+ cells. In blood samples diluted 1/5 or 1/10, and cultured in the presence of cytomegalovirus (CMV) or varicella-zoster virus (VZV), mean peak levels of 2.8% and 1.4% IFNgamma+CD4+ cells were recorded at 120 h. The levels of cells producing cytokines other than IFNgamma were generally much lower and, in the case of IL-4 and IL-13, difficult to distinguish from background levels recorded in cultures with medium only. Kinetic studies of cytokine production by PBMCs showed a pattern similar to that of whole blood with peak levels of IFNgamma-producing cells recorded at 72 h. The increased levels of IFNgamma production after culture for 72 h were due to an expansion of the numbers of cytokine-producing cells responsive to a specific stimulus. Antigen-specific cells are usually present only at low levels in peripheral blood and may not be detected following simple activation for a few hours. To reach a level of detection in such cases, culture of diluted blood for several days is recommended.

Marked elevation of the chemokine CCL18/PARC in Gaucher disease: a novel surrogate marker for assessing therapeutic intervention

Gaucher disease is characterized by storage of glucosylceramide in lysosomes of tissue macrophages as the result of an autosomal recessively inherited deficiency in glucocerebrosidase. Progressive accumulation of these glycolipid-laden Gaucher cells causes a variety of debilitating symptoms. The disease can be effectively treated by costly intravenous infusions with recombinant glucocerebrosidase. Chitotriosidase is massively secreted by Gaucher cells and its plasma levels are used to monitor efficacy of enzyme therapy. Broad-scale application is hampered by the common genetic defect in this surrogate marker. We report that in plasma of symptomatic patients with Gaucher disease the chemokine CCL18 is on average 29-fold elevated, without overlap between patient and control values (median control plasma level is 33 ng/mL, range, 10-72 ng/mL; median Gaucher plasma level is 948 ng/mL, range, 237-2285 ng/mL). Plasma CCL18 concentrations decrease during therapy, comparably to chitotriosidase levels. Immunohistochemistry demonstrates that Gaucher cells are the prominent source of CCL18. Plasma CCL18 levels can serve as alternative surrogate marker for storage cells in patients with Gaucher disease and monitoring of plasma CCL18 levels proves to be useful in determination of therapeutic efficacy, especially in patients who are deficient in chitotriosidase activity. The potential physiologic consequences of chronically elevated CCL18 in patients with Gaucher disease are discussed.

Murine and human hematopoietic colony formation: a possible regulatory role for intracellular histamine

Increasing number of data suggests that locally produced histamine is involved in regulation of hematopoiesis. In this study the granulocyte/macrophage (CFU-GM) colony formation by normal murine or human bone marrow cells, leukaemic colony formation (CFU-L) by a murine leukemia cell line (WEHI 3B), and colony formation by bone marrow cells from patients with chronic myeloid leukemia (CML) have been examined. We detected mRNA and protein expression of histidine decarboxylase (HDC), the only enzyme responsible for histamine synthesis both in normal bone marrow progenitor cells and in leukaemic progenitors. The significance of in situ generated histamine was shown on colony formation by inhibitory action of alphaFMH (blocking HDC activity, i.e. de novo histamine formation) and by N,N-diethyl-2-[4-(phenylmethyl)phenoxy]-ethanamine-HCl (DPPE) disturbing the interference of histamine with intracellular binding sites. These data provide further confirmation of the role of histamine in development and colony formation of bone marrow derived cells.

Differential expression of cytokine mRNA in skin specimens from patients with erythema migrans or acrodermatitis chronica atrophicans

Erythema migrans, the characteristic skin manifestation of acute Lyme borreliosis, is a self-limited lesion. In contrast, acrodermatitis chronica atrophicans, the typical cutaneous manifestation of late Lyme borreliosis, is a chronic skin condition. In an effort to understand pathogenic factors that lead to different outcomes in dermatoborrelioses, skin biopsy samples from 42 patients with erythema migrans and 27 patients with acrodermatitis chronica atrophicans were analyzed for mRNA expression of five pro-inflammatory cytokines (tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, interferon-gamma, and interleukin-2) and two anti-inflammatory cytokines (interleukin-4 and interleukin-10) by in situ hybridization with cytokine-specific riboprobes. Among the 27 patients who had erythema migrans alone with no associated signs or symptoms, the major cytokines expressed in perivascular infiltrates of T cells and macrophages were the pro-inflammatory cytokine interferon-gamma and the anti-inflammatory cytokine interleukin-10. In the 15 erythema migrans patients who had associated signs and symptoms, including headache, elevated temperature, arthralgias, myalgias, or fatigue, a larger number of macrophages and greater expression of macrophage-derived pro-inflammatory cytokines, tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6, were also found. In comparison, infiltrates of T cells and macrophages in the skin lesions of acrodermatitis chronica atrophicans patients had very little or no interferon-gamma expression. Instead, they usually expressed only the pro-inflammatory cytokine tumor necrosis factor alpha and the anti-inflammatory cytokine interleukin-4. Thus, the activation of pro-inflammatory cytokines in erythema migrans lesions, particularly interferon-gamma, seems to be important in the control of the spirochetal infection. In contrast, the restricted pattern of cytokine expression in acrodermatitis chronica atrophicans, including the lack of interferon-gamma, may be less effective in spirochetal killing, resulting in the chronicity of this skin lesion. J Invest Dermatol 115:1115-1123 2000

Abundant expression of CD40 and CD40-ligand (CD154) in paediatric Langerhans cell histiocytosis lesions

The pathogenesis of Langerhans cell histiocytosis (LCH) is obscure, partly because the events leading to activation of Langerhans-like lesional cells (LCH cells) and associated T cells, and the excessive cytokine production by these cells are unknown. The interaction between CD40 on antigen-presenting cells (APC) like Langerhans cells and CD40 ligand (CD40L) (CD154) expressed by activated CD4+ T cells, is essential for the activation of both the APC and the T cells and results in upregulation of APC functions and initiation of immunoreactivity. The effects of CD40-CD40L interaction include increased expression of co-stimulatory and adhesion molecules, proliferation, and production of pro-inflammatory cytokines and proteolytic enzymes, all features of LCH. Using immunohistochemistry, we analysed the in situ presence of the co-stimulatory molecules CD40 and CD40L in 15 fresh frozen biopsies of LCH lesions in children. The cells producing these molecules were identified by double staining for CD1a on LCH cells and CD3 on T cells. Prominent expression of CD40 by LCH cells and CD40L by T cells was found in all 15 specimens regardless of the source of specimen or characteristics of the patient. The findings of high expression of CD40 and CD40L in all specimens imply a key role for the CD40-CD40L adhesion pathway in the pathogenesis of LCH. Since this interaction is an accessible and realistic target for immunotherapy, these findings prompt speculation on the use of blocking antibodies to CD40 or to CD40L in the treatment of LCH.

Critical illness polyneuropathy and myopathy (CIPNM): evidence for local immune activation by cytokine-expression in the muscle tissue

In a longitudinal prospective study a muscle biopsy was taken from 30/32 (33%) of the 98 patients who developed critical illness polyneuropathy and myopathy (CIPNM). Neuropathic changes were found in 37%, myopathic in 40%, and a combination in 23% of the biopsies. The immunohistopathology showed macrophages and Th-cells in 40% and 60% of the muscle biopsies respectively. Small mainly perivascular infiltrates contained macrophages and Th-cells. ICAM-1, VCAM and MAC were found on the vascular endothelium in 58%, 53% and 79% respectively. In all biopsies there was an upregulation of both HLA-I and HLA-DR. Proinflammatory cytokines and TNFalphaR75 were also produced locally (IL-1beta in 71%, IFN-gamma in 40%, IL-12 in 73%, TNFalphaR75 in 90%). The anti-inflammatory cytokine IL-10 was simultaneously expressed in 96% of the biopsies. HLA-DR, TNFalphaR75 and IL-10 differed significantly when compared with control muscle biopsies. Our data provide evidence that small numbers of activated leukocytes producing both pro- and anti-inflammatory cytokines infiltrate skeletal muscle of CIPNM patients. We propose that the local balance of leukocyte activities is of importance in the pathophysiology of muscle weakness in CIPNM.

In situ production of gamma interferon, interleukin-4, and tumor necrosis factor alpha mRNA in human lung tuberculous granulomas

Human tuberculous granulomas from five adults undergoing surgery for hemoptysis were analyzed by nonradioactive in situ hybridization for tumor necrosis factor alpha (TNF-alpha), gamma interferon (IFN-gamma), and interleukin-4 (IL-4) gene expression. All of the patients produced TNF-alpha mRNA. Three patients stained positive for both IFN-gamma and IL-4 mRNA; the other two stained positive for IFN-gamma but not IL-4 mRNA. Heterogeneity between the granulomas was observed in those patients staining positive for both IFN-gamma and IL-4 mRNA; these patients exhibited granulomas having IFN-gamma and not IL-4 mRNA as well as granulomas positive for both cytokine mRNAs. There was no evidence of caseation in these granulomas, and the cytokine patterns may represent events in the evolution of the granuloma. However, in those granulomas exhibiting caseous necrosis, very little IFN-gamma or IL-4 mRNA was observed, implying that progression of the granuloma is accompanied by a down regulation of T-cell responses. TNF-alpha mRNA expression was highest in patients with both IFN-gamma and IL-4 mRNA. Populations of CD68 positive macrophage-like cells within the granulomas produce mRNA for TNF-alpha, IFN-gamma, and IL-4. This implies that macrophages within the tuberculous granuloma may not be dependent on T-cell cytokines for modulation of their function but may be able to regulate their own activation state and that of the surrounding T cells. These findings have implications on the delivery of immunotherapies to patients with tuberculosis.

Measurement of cytokines in clinical samples using immunoassays: problems and pitfalls

With the explosion in interest in cytokines and an increasing understanding of their possible involvement in the pathogenesis of many diseases, the number of studies measuring cytokines in body fluids has increased markedly over the last 5 to 10 years. However, it is readily apparent from the literature that the level of awareness of the many factors that can potentially influence the results obtained is very low. Such factors are likely to contribute considerably to the disparities seen among similar types of study. These include assay properties such as standardization and specificity, type of sample and sample handling, and many biological influences such as age, sex, ethnic background, and diurnal rhythmicity. Clearly, it is not possible to control for all these factors, but a minimum evaluation of assays should be carried out as described, including recovery and parallelity studies using relevant samples and the establishment of reproducibility and normal healthy population levels. An awareness of these factors, which is the purpose of this review, may hopefully lead to an improvement in the quality of studies incorporating the measurement of cytokines in clinical samples and should aid in the interpretation of the data.

Breast tumour cell-induced down-regulation of type I collagen mRNA in fibroblasts

This study investigated the modulation of type I collagen gene expression in normal fibroblasts by breast tumour cells. Northern analysis of total RNA extracted from stages I, II and III breast tumour tissue revealed that collagen mRNA levels were elevated in stage I tumours compared to the adjacent normal breast tissues, whereas they were decreased in stages II and III breast tumours. This aberrant collagen gene expression was confirmed by non-radioactive RNA:RNA in situ hybridization analysis of 30 breast carcinomas which localized the production of type I collagen mRNA to the stromal fibroblasts within the vicinity of the tumour cells. In order to determine whether the tumour cells were directly responsible for this altered collagen production by the adjacent fibroblasts, breast tumour cell lines were co-cultured with normal fibroblasts for in vitro assessment of collagen and steady-state collagen RNA levels. Co-culture of tumour cells and normal fibroblasts in the same dish resulted in down-regulation of collagen mRNA and protein. Treatment of the fibroblasts with tumour-cell conditioned medium also resulted in decreased collagen protein levels but the mRNA levels, however, remained unaltered. These results suggested that the tumour cells either secrete a labile 'factor', or express a cell surface protein requiring direct contact with the fibroblasts, resulting in down-regulation of collagen gene expression. Modulation of the ECM is a common characteristic of invading tumour cells and usually involves increased production of collagenases by the tumour cells or stromal fibroblasts. This study showed that tumour cells were also able to modulate collagen mRNA production by stromal fibroblasts, which may facilitate tumour cell invasion and metastasis.

Comparison of detection techniques for cytokine reverse transcriptase polymerase chain reaction; digoxigenin-labeled polymerase chain reaction permits sensitive detection of cytokine mRNA in rat heart allografts

The polymerase chain reaction (PCR) is a sensitive method for the analysis of cytokine mRNA expression. The amount of specific mRNA in tissues involved in an inflammatory immune response can be low and therefore requires highly sensitive detection of the PCR products. In our study we have compared different detection techniques in order to replace the commonly used detection by means of radiolabeled probes. Besides the detection of DNA in agarose gels by ethidium bromide (EB), we used detection by digoxigenin (DIG)-labeled probes, as well as the direct incorporation of DIG-labeled nucleotides in the PCR, in comparison to detection by means of 32P-labeled probes. In vitro activated rat lymph node cells, lymph node tissue, and acutely or chronically rejected rat heart allografts were examined for expression of mRNA of the cytokines IL-2 and IFNgamma. The directly DIG-labeled PCR appeared to be the best alternative for detection of PCR products by means of radiolabeled probes. While IL-2 mRNA was not detected by means of EB and IFNgamma mRNA was only detected at the highest PCR cycle numbers in acutely and chronically rejected rat heart allografts, both cytokine mRNA's were readily detected by directly DIG-labeled PCR.

Novel methods to monitor antigen-specific cytotoxic T-cell responses in cancer immunotherapy

Monitoring cytotoxic T lymphocyte (CTL) responses to tumor antigens that have been defined at the molecular level has become essential to assess novel approaches to the specific immunotherapy of cancer. Nevertheless, because of the low affinity of the interactions between T-cell receptors and their ligands, there are no straightforward, well-standardized methods to meet this need. In this review, we describe several novel methods to track antigen-specific CTL responses.

Expression of accessory molecules and cytokines in acute EAE in marmoset monkeys (Callithrix jacchus)

Accessory molecules and cytokines are involved in the immunopathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) in rodent models, and are potential targets for immunotherapy. Evaluation of such experimental therapies requires appropriate animal models. Therefore, we analysed the expression of selected accessory molecules and cytokines in the brain of marmoset monkeys (Callithrix jacchus) with acute EAE, a newly described non-human primate model for MS. All animals experienced active disease clinically and histopathologically with strong resemblance to MS. Perivascular infiltrates of mononuclear cells showed abundant expression of CD40. CD40 was expressed on macrophages, indicating that T cell priming and macrophage effector functions may result from local CD40-CD40L interactions. CD40 ligand (CD40L) and B7-2 (CD86) were also expressed, but to a lower extent, while B7-1 (CD80) expression was limited. Both pro-inflammatory and anti-inflammatory cytokines were produced within individual lesions during active disease (IFN-alpha, IFN-gamma, TNF-alpha, IL-1alpha, IL-1beta, IL-2, IL-4, IL-10 and IL-12). This suggests that relative levels rather than sequential expression of Th1- and Th2-type cytokines determine disease activity. These findings demonstrate the value of EAE in marmoset monkeys as a model to assess the role of accessory molecules and cytokines in multiple sclerosis, and to evaluate targeted intervention.

Immunohistochemical detection of cytokines in paraffin-embedded mouse tissues

We have successfully developed a method for the immunohistochemical detection of interleukin 2 (IL-2), IL-4, IL-6, IL-10O, IFNgamma and TNFalpha using monoclonal antibodies (MAb), in sections of mouse tissue embedded in paraffin wax. The method involved fixation in periodate-lysine-paraformaldehyde (PLP), rapid dehydration and infiltration under vacuum with paraffin wax at 54 degrees C. Comparative observations demonstrated that the method gives equivalent or better results than formaldehyde fixed, frozen sections. Since reliable controls, both positive and negative, are paramount for interpretation of immunohistochemical staining, such controls were determined. The following tissues were shown to be suitable as positive controls when using paraffin-embedding: spleen for the detection of TNFalpha, small intestine for IL-2, IL-4 and IL-10, and HSV-1 infected eyes for IL-6 and IFNgamma. We conclude that PLP fixation and low temperature paraffin-embedding is a method which provides both preservation of excellent tissue morphology and reliable immunohistochemical identification of cytokines. These attributes will be invaluable in a wide variety of experimental situations.

Single cell analyses of cytokine production

Subsets of T lymphocytes have been defined by their secretion of polarized patterns of cytokines. Type 1 and Type 2 subsets have been characterized in a variety of model systems both in vivo and in vitro and are a useful framework for studying immune responses. Recent technical advances have made it possible to analyze cytokine production by these populations at the level of individual cells.