Oral immunization with poly-(D,L-lactide-co-glycolide) and poly-(L-lactic acid) microspheres containing pneumotropic bacterial antigens

Encouraged by recent findings showing the usefulness of nonreplicating antigen delivery systems in the induction ofmucosal immune responses, we investigated microspheres as a means to deliver LW 50020, an immunomodulator consisting of lysates of seven common respiratory pathogens. BALB/c mice were orally immunized with LW 50020 encapsulated into poly-(D,L-lactide-co-glycolide) (PLG) and poly-(L-lactic acid) (PLA) microspheres prepared by either a solvent-evaporation or a solvent-extraction double-emulsion technique. Particle uptake into intestinal Peyer's patches, induction of antibodies in sera and secretion of immunoglobulins by isolated Peyer's patches, lungs and spleen lymphocytes were investigated. Our results revealed size and surface characteristic-dependent uptake of microspheres into Peyer's patches. Microsphere translocation into Peyer's patches was efficient for 0.8-microm microspheres, but poor for 2.0-microm and surface-modified microspheres. We showed an enhanced immune response in the lungs and sera following oral immunization with 0.8-microm PLG solvent-evaporation microspheres. The immunomodulation was statistically significant as compared to free LW 50020. In contrast, oral immunization with other preparations caused reduced or absent modulation of the immune response compared to 0.8-microm microspheres and free antigen. These findings indicate that microspheres displaying small particle sizes, rapid antigen release and high antigen content provide optimal tools to deliver orally applied antigens.

The aging immune system: primary and secondary alterations of immune reactivity in the elderly

The function of the immune system is known to decline in the elderly. The present communication will show that, similar to the situation in children, it is necessary to distinguish between primary and secondary alterations of the immune reactivity in the elderly. The primary immunological change in the elderly is the age-dependent intrinsic decline of immune responsiveness that is also observed in healthy persons, i.e., those selected according to the criteria of the SENIEUR Protocol of EURAGE (European Community Concerted Action on Aging). Secondary immunological changes are due to underlying diseases and various environmental factors, including diet, drug intake, physical activity, etc. While primary immunodeficiencies of the elderly are not, or only to a very minor extent, presently influenced by therapeutic measures, secondary alterations of the immune function offer further possibilities for corrective measures. Clinically, the consequences of impaired immune function in the elderly include increased susceptibility to infectious disease, the emergence of tumors, and increased autoimmune reactions, the latter albeit often without concomitant autoimmune disease. In fact, autoimmune diseases in generally begin to develop at younger ages, but their consequences are major factors affecting the quality of life of the elderly. Investigations of basic molecular and cellular aspects of the aging immune system are, therefore, of theoretical, clinical and socioeconomic interest.

Co-expression of ICAM-1, VCAM-1, ELAM-1 and Hsp60 in human arterial and venous endothelial cells in response to cytokines and oxidized low-density lipoproteins

T-cells and monocytes are the first cells infiltrating the arterial intima during the early stages of atherogenesis. Recently our laboratory has provided evidence that T-cells isolated from atherosclerotic intima reacts against heat shock protein 60 (Hsp60). Transmigration of activated T-cells into the intima is mediated by adhesion molecules (ICAM-1; VCAM-1; ELAM-1) expressed on activated endothelial cells. Here we studied the potential of cytokines (TNF-alpha, IFN-gamma, IL-1). Escherichia coli lipopolysaccharide (LPS), native and oxidized low-density lipoprotein (LDL; oxLDL) and high temperature to induce adhesion molecules as well as Hsp60 and Hsp70 expression in human endothelial cells (EC). On Northern blots, a strong signal for ICAM-1, VCAM-1 and ELAM-1 was detected after 4 h, which thereafter declined, but did not reach the basal level of untreated control cells. Heat shock induced the expression of Hsp60 and Hsp70 but not of adhesion molecules. EC were cultivated in serum-free medium, which led to the expression of adhesion molecule transcripts. Addition of LDL or oxLDL to these ECs did not alter the expression of these transcripts. The production of adhesion molecule proteins was analysed by flow cytometry. In human venous endothelial cells (HVEC) and human arterial endothelial cells (HAEC) ICAM-1 and VCAM-1 production was permanently highly induced, whereas the high level of ELAM-1 production at 4 h disappeared after 24 h. Furthermore, only HAEC, but not HVEC, produced ICAM-1, VCAM-1 and ELAM-1 after stress by moderately and highly oxLDL. LDL and oxLDL did not induce the production of Hsp60 and Hsp70. The present study demonstrates the co-expression of Hsp60 and adhesion molecules in arterial and venous EC in response to cytokine and LPS exposure, and that oxLDL is an efficient inducer of adhesion molecules in arterial EC and not in venous EC. These features provide the prerequisites for a cellular immune reaction against Hsp60 expressed by stressed EC in the initial stages of atherosclerosis.

Development of spontaneous autoimmune thyroiditis in Obese strain (OS) chickens

Chickens of the Obese strain (OS) are known to develop spontaneous autoimmune thyroiditis (SAT) in the first 2-3 weeks post-hatching, but onset and severity of SAT for this period among sublines of OS chickens has not yet been analysed in detail. In the present paper, we described the kinetics of SAT in age-matched OSB13B13C, OSB5B5C, OSB15B15INN and OSB5B5INN chicken sublines. The results revealed no thyroid infiltration in OS fetuses at 20th ED of the analysed sublines. Mononuclear cell infiltration of thyroid was first noted in 2-4-day-old chickens, followed by aggravation of thyroiditis in 4-week-old OSB13B13C and OSB15B15INN chickens and in 5-week-old OSB5B5C birds. Interestingly, two subpopulations of OSB5B5INN chickens were found with different kinetics of SAT development: one with degree of SAT lower than 40%, was designated "low responders" and the other, with similar degrees of SAT as the other three sublines, was characterized as "high responders". Our results allow an age-dependent prediction of SAT development among OS chickens and the rational design of animal experiments, particularly for assessing the relevance of therapeutic interventions.

Epitope specificity of anti-heat shock protein 65/60 serum antibodies in atherosclerosis

Levels of specific antibodies (Ab) against mycobacterial and human heat shock protein (hsp) 65/60 are increased in the sera of patients with atherosclerotic lesions and have been demonstrated to be capable of mediating endothelial cytotoxicity. To clarify the antigen epitopes recognized by these serum Abs, Ab binding to hsp65 deletion mutants (Dms), as well as to overlapping 15-mer and 8-mer hsp65 peptides, was assessed. Western blotting of hsp65 Dms indicated the presence of at least one epitope between amino acid (aa) residues 171 and 276, recognized by both high-titer sera and affinity-purified anti-hsp65/60 Ab. Fluorescence immunoassays using 53 15-mer peptides and Pin ELISA using 526 7-mer peptides demonstrated three distinct, conserved sequences with high affinity to high-titer sera and purified anti-hsp65/60 Ab. Two N-terminal sequences, aa 97-109 and aa 179-187, and one C-terminal sequence, aa 504-512, were identified. These three epitopes recognized by anti-hsp65/60 Ab may serve as autoantigens in certain circumstances in vivo. This phenomenon could contribute to the initiation of atherosclerosis by an autoimmune reaction.

Macrophage-lysis mediated by autoantibodies to heat shock protein 65/60

Macrophages in atherosclerotic lesions have been shown to express high amounts of heat shock protein 60 (hsp60), a highly conserved protein. Patients with atherosclerosis have high titers of anti-hsp65/60 antibodies (Ab) recognizing macrophages in the lesions. To elucidate the role of anti-hsp65/60 Ab in macrophage cytotoxicity, human high titer serum and purified anti-hsp65/60 Ab were tested on in vitro heat-stressed cells of a human macrophage cell line (U937) and macrophages derived from peripheral blood. Application of heat stress at 42 degrees C for 30 min resulted in marked upregulation of hsp60 mRNA, followed by increased protein expression as determined by Northern blot and FACS-analysis, respectively. Compared to unstressed cells, high titer serum and anti-hsp65/60 Ab preferentially bound to the surface of stressed U937 macrophages, but not control antibodies. Furthermore, high titer serum and anti-hsp65/60 Ab exerted significant (P < 0.01) complement-mediated cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) on stressed 51Cr-labelled U937 and peripheral blood derived macrophages. Thus, macrophages expressing hsp60 can be lysed by autoantibodies against hsp65/60, which may contribute to cell death in atherosclerotic plaques in vivo.

Immunochemical mapping of gonadotropins

As a glycoprotein hormone, human chorionic gonadotropic (hCG) is not a single molecular entity but this term rather comprises an array of molecular variants such as hCG, hCG beta, hCGn, hCG beta n, hCG beta cf, -CTPhCG, hCG beta CTP, deglyhCG, asialohCG, hCGav and the closely related molecules hLH, hLH beta and hLH beta ef. The advent of monoclonal antibodies (MCA), the availability of ultrasensitive detection systems and the recent determination of the crystal structure of hCG, made it possible to design special purpose diagnostic and clinical research immunoassays for hCG-like molecules. For more than a decade we and others have tried to refine epitope maps for hCG and related molecules by means of a large panel of MCA, naturally occurring metabolic variants of hCG (hCGn, hCG beta, hCG alpha, hCG beta cf, hCG beta CTP), homologous hormones and subunits of various species (e.g. hLH, hLH beta, hFSH, hTSH, oLH, rLH beta), chemically modified molecules (deglyhCG, asialohCG, tryptic and chymotryptic hCG beta and hCG alpha fragments) and synthetic peptides (octapeptides and longer). It appeared that all epitopes on molecular hCG-variants recognized by our MCA are determined by the protein backbone. Except for the two major epitopes on hCG beta CTP and parts of two antigenic domains on hCG alpha, epitopes on hCG-derived molecules are determined by the tertiary and quarternary structure. Operationally useful descriptive epitope maps were designed including information on assay suitability of antigenic determinants. On this basis we established ultrasensitive time-resolved fluoroimmuno-assays for hCG, hCG and hCGn, hCG beta and hCG beta n and hCG beta cf, hCG alpha and additional assays recognizing different spectra of hCG-variants. Such assay have been applied by us and others to the detection of pregnancy, early pregnancy loss, choriocarcinoma, testicular cancer, other cancers and prenatal diagnosis. However, as the molecular structure of many epitopes utilized in immunoassays of different laboratories was not resolved, comparability of results was not satisfactory. Consequently, attempts were made to compare schematic epitope maps from different research institutions. The situation has been much improved by solving the three-dimensional (3D) structure of hCG. It has been shown that hCG is a member of the structural superfamily of cystine knot growth factors like NGF, PDGF-B and TGF-beta. Each of its subunits is stabilized in its topology by three disulfide bonds forming a cystine knot. Moreover, it turned out that the disulfide bridges in their majority have previously been wrongly assigned. Computer molecular modeling of crystallographic coordinates of hCG and subsequent selective combined--PCR-based and immunological--mutational analyses of hCG beta expressed via the transmembrane region of a MHC molecule made it possible to more precisely localize epitopes on hCG-derived molecules. Although the entire surface of hCG has to be regarded as potentially immunogenic there seems to be hot spots where epitopes are clustered in antigenic domains. These are located on the first and third loops protuding from the cystine knots of both subunits and are possibly centered around the knot itself. Ultimate answers on epitope localizations will be given by the crystal structure determination of hCG complexed with different Fabs.

Disturbed immunoendocrine communication via the hypothalamo-pituitary-adrenal axis in murine lupus

Immune reactions and mitogen stimulation of mammals and chickens lead to an increase of glucocorticoid (GC) plasma levels concomitant with the immune response. Interleukin (IL) 1, one of the most important glucocorticoid increasing factors produced by cells of the immune system, acts via the hypothalamo-pituitary-adrenal (HPA) axis. This pattern of immunoendocrine feedback communication is altered in autoimmune disease (AID) and represents a possible site of action for GC therapy. In the present study we investigated the role and possible underlying mechanisms of a disturbed immunoendocrine communication via the HPA axis in murine lupus. We analyzed the response to recombinant human (rhu) IL-1alpha in AID-prone mice [NZB, NZW, (NZB/NZW)F1, MRL/MP-lpr] in comparison to nonautoimmune, normal control mice (Swiss, C3H/HeJ, MRL/MP-+/+) at different levels of the HPA axis. To this end, we quantified the plasma levels of ACTH, corticosterone, and corticosterone-binding globulin (CBG) and determined various pathology parameters for autoimmunity. AID-prone mice produced nearly the same levels of plasma corticosterone after injection of rhu IL-1alpha as normal mice, but had baseline corticosterone levels consistently higher, thus resulting in significantly lower corticosterone increasing ratios. ACTH levels increased after rhu IL-1alpha injection, but there was no clearcut difference in the increasing ratios of AID-prone and normal strains. CBG levels showed no difference. As expected, there was a correlation of pathology parameters for autoimmunity and the altered immunomodulatory response to rhu IL-1alpha per group. On an individual basis, there was no such correlation. In conclusion, our results confirm the existence of a disturbed immunoendocrine communication in AID-prone mice. This disturbance clearly differs from individual to individual and also among different types of AID.

Properties of low density lipoproteins relevant to oxidative modifications change paradoxically during aging

Atherosclerosis is a common problem among the elderly. Because lipid peroxidation is considered a contributor to the development of atherosclerosis, we compared oxidative properties of lipoproteins in an otherwise healthy (SENIEUR-classified) aged population (65-74 years) with young controls (18-30 years). Relative amounts of oxidatively altered low density lipoprotein (LDL), estimated by means of an antibody against LDL modified by 4-hydroxynonenal, a product of lipid peroxidation, were increased marginally in serum from the elderly (9.8 vs. 7.4%, P = 0.07). In contrast, isolated LDL from the elderly revealed a decreased susceptibility to in vitro oxidation: the lag time was increased (2.34 vs. 2.10 h, P < 0.01), and the maximal rate of LDL oxidation decreased (0.88 vs. 1.01 O.D./h, P = 0.001). However, there were no age-related changes in lipid composition of native LDL and consumption of fatty acids during in vitro oxidation. The serum concentrations of ascorbic acid and most lipophilic anti-oxidants (the latter expressed per g serum lipids) were significantly decreased in the elderly except tocopherols which tended to be higher. In conclusion, our data reveal paradox age-related alterations of LDL as to its behaviour in oxidation in vivo vs. in vitro.

The role of heat shock proteins in protection and pathophysiology of the arterial wall

The arterial wall is an integrated functional component of the circulatory system that is continually remodelling in response to various stressors, including localized injury, toxins, smoking and hypercholesterolaemia. These stimuli directly or indirectly cause changes in blood pressure and damage to the vessel wall, and eventually induce arterial stiffness and obstruction. To maintain the homeostasis of the vessel wall, the vascular cells produce a high level of stress proteins, also known as heat shock proteins, which protect against damage during haemodynamic stress. However, an immune reaction to heat shock proteins might contribute to the development of atherosclerosis. We hypothesize that the induction of heat shock proteins is beneficial in the arterial wall's response to stress but is harmful in certain other circumstances.

Endothelial cell apoptosis is a primary pathogenetic event underlying skin lesions in avian and human scleroderma

The mechanism that may cause degenerative fibrotic skin lesions was studied in situ using skin biopsies from patients with systemic sclerosis (SSc), localized scleroderma, or keloids, and at the initial disease stage in the University of California at Davis (UCD) lines 200/206 chickens, which develop a hereditary systemic connective tissue disease resembling human SSc and permit study of disease stages not accessible in humans. Frozen skin sections were analyzed simultaneously for apoptosis by terminal deoxynucleotidyl transferase-mediated FITC-dUTP nick end labeling and indirect immunofluorescence staining of cell markers with tetramethylrhodamine isothiocyanate conjugates. The results showed that endothelial cells are clearly the first cells to undergo apoptosis in the skin of UCD-200/206 chickens, a process that seems to be induced by anti-endothelial cell antibodies. In human fibrotic skin diseases, apoptotic endothelial cells could only be detected in early inflammatory disease stages of SSc and localized scleroderma.

Phenotypic and functional characterization of CD11c+ dendritic cell population in mouse Peyer's patches

The antigen-presenting cell system in the gastrointestinal tract, one of three main sites (skin and lung being the others) of primary antigen contact, is poorly understood. Our study focused on dendritic cells (DC) as possible candidates for antigen uptake, processing and presentation in mucosal inductive sites, such as Peyer's patches (PP). To investigate the morphology, immunophenotype and stimulatory activity of intestinal DC, a procedure was developed to obtain a cell population by using collagenase digestion of PP, density centrifugation and cell sorting on the basis of CD11c expression. The resultant low-density cell fraction consisted of a nonadherent cell population expressing different intensities of CD11c that could at least be characterized by typical DC morphology (e.g. abundant cytoplasma with veil-like cytoplasmatic dendrites, irregularly shaped nuclei, multivesicular and multilamellar bodies), constitutive levels of surface MHC class II, the presence of macrophage-specific markers, such as F4/80, Mac-I and Fc receptors, respectively, on subpopulations of CD11c+ sorted cells and expression of adhesion and co-stimulatory receptors like ICAM-1 and CD44. The capability of this low-density CD11c+ fraction to stimulate T cell responses was demonstrated in primary allogeneic mixed-lymphocyte reactions (MLR). Herein, we show that the freshly isolated CD11c+ cells showed weak accessory function, but develop this capacity following short-term culture in vitro in the presence of granulocyte/macrophage colony-stimulating factor. Although the nature and functional capacity of the isolated CD11c+ needs further clarification, these preliminary results describing phenotype and accessory function provide some evidence that these cells isolated from the PP may be immature forms of DC and play a crucial role as antigen-presenting cells with important implications for understanding the complex network regulating intestinal antigen uptake, processing and presentation.

Relative location of epitopes involved in synergistic antibody binding using human chorionic gonadotropin as a model

We systematically screened a large panel of well-characterized monoclonal antibodies (mAb) directed towards various epitopes on human chorionic gonadotropin (hCG) for synergistic binding of 125I-hCG when they were adsorbed to a solid phase. The epitope locations involved in synergy were then related to the crystal structure of hCG and discussed in accordance with available data on the hCG epitopes. Enhanced binding of hCG was specific for certain pairs of mAb and was reflected in a 3-50-fold increased apparent functional affinity constant for hCG. Surface plasmon resonance revealed that when the mAb were captured by a polyclonal anti-IgG1 coupled to the Biacore chip, the off rates for hCG were significantly slower with synergistic mAb combinations than for the corresponding single mAb or nonsynergistic pairs of mAb, whereas the on rates did not differ appreciably. Each of the two antibodies involved in synergistic binding of hCG (more than 3-fold compared to additive binding of the two mAb) always belonged to a different epitope cluster in a separate antigenic domain on hCG. Synergistic epitope combinations on holo-hCG were located in similar structural planes. Combinations of mAb directed towards the epitope clusters alpha 2/beta 3/5, alpha 2/hCG beta CTP (C-terminal peptide) and beta 3/5/hCG beta CTP showed the strongest enhancement, with binding more than 10-fold greater than the sum of 125I-hCG bound to the individual mAb, followed by pairs of mAb directed towards the epitope groups beta 1/beta 3/5, c 1/2/beta 3/5, beta 1/alpha 2, and alpha 2/alpha 3/5 (3-9-fold). The greater frequency of synergy obtained with the linear epitopes of the hCG beta CTP can be ascribed to their greater molecular flexibility relative to the constrained discontinuous epitopes on hCG alpha and core-hCG beta (residues 1-112). In general, these studies provide a method for rapid screening of synergistic antibody pairs which also helps to identify non-overlapping epitopes that are accessible in similar structural planes. In turn, this facilitates the design of high-affinity bispecific antibodies targetted to a single antigen molecule.

Preparation and characterization of poly-(D,L-lactide-co-glycolide) and poly-(L-lactic acid) microspheres with entrapped pneumotropic bacterial antigens

Poly-(lactide-co-glycolide) microspheres with entrapped antigen have shown considerable promise as controlled release vaccines. To enhance the immunomodulatory effect of LW 50020, a bacterial lysate of seven common respiratory pathogens used perorally as an immunomodulator, we prepared poly-(D,L-lactide-co-glycolide) (PLG) and poly-(L-lactic acid) (PLA) microspheres with entrapped immunomodulator by solvent evaporation or solvent extraction double emulsion techniques. Physical properties, such as particle size, LW 50020 entrapment rate, antigen release patterns and morphological characteristics were investigated. All preparations displayed a high degree of antigen loading up to 95%, whereas size, surface morphology and antigen release patterns were significantly influenced by the method of preparation and the polymer components used. Solvent evaporation microspheres are porous particles from 0.8 micron to 2.0 microns in diameter, that show a rapid antigen release for PLG, and a moderate antigen release for PLA microspheres within 33 days. Solvent extraction microspheres have proven to be particles from 1.1 microns to 5.0 microns in diameter showing a smooth surface and a medium antigen release rate over 33 days. SDS-PAGE and immunoblotting of extracted antigen confirmed that the molecular weight and antigenicity of the immunomodulator remained unaltered by the entrapment procedure.

Regression of arteriosclerotic lesions induced by immunization with heat shock protein 65-containing material in normocholesterolemic, but not hypercholesterolemic, rabbits

Previous studies in our laboratory have shown that arteriosclerotic changes can be induced in normocholesterolemic rabbits by immunization with mycobacterial heat shock protein 65 (hsp 65). To investigate the possible regression of such vascular lesions, 63 male New Zealand White rabbits were treated either by triple immunization with fortified Freund's complete adjuvant containing 5 mg/ml Mycobacterium tuberculosis, a hsp 65-rich material, by administration of a 0.2% cholesterol-rich diet only or by a combination of both immunization and cholesterol-rich diet. Sixteen weeks after the first immunization, half of the animals of each group were sacrificed, and as expected arteriosclerotic lesions in the intima of the aortic arch were found in 8 of 10 immunized animals. The remaining animals were sacrificed 16 weeks thereafter, having been maintained on a normal, non-cholesterol-enriched diet from week 16 to 32. Only 3 of 10 rabbits immunized showed moderate lesions in their aortae 32 weeks after the first immunization. On the other hand, atherosclerotic lesions induced by cholesterol-rich diet, or by immunization plus cholesterol-rich diet, showed no significant regression between 16 and 32 weeks. In conclusion, the early inflammatory stages of arteriosclerotic lesions induced by immunization with hsp 65 can regress in the absence of additional risk factors for atherosclerosis, such as a cholesterol rich diet.

Comparison of low density lipoprotein uptake by different human lymphocyte subsets: a new method using double-fluorescence staining

A method to determine low density lipoprotein (LDL) uptake of distinct lymphocyte subpopulations was developed using fluorescent LDL and subsequent staining of lymphocyte subsets with biotinylated monoclonal antibodies plus streptavidin-CyChrome. LDL uptake was detected on a single cell level and semiquantified by FACS analysis. This method allows comparison of defined lymphocyte subsets from different individuals and excludes the falsifying influence of individual differences in subset distribution, which may occur in studies on total peripheral blood lymphocytes (PBL). Investigation of total PBL and lymphocyte subsets of 20 healthy volunteers (8 male, 12 female) showed the following. i) Different lymphocyte subsets exhibited highly significant differences in LDL uptake, with NK cells (CD16) showing a higher uptake than T (CD3) and B cells (CD19); CD8-positive cells exhibited higher values than CD4-positive cells. ii) These differences are due to specific, LDL-receptor (LDL-R)-mediated LDL uptake. iii) Inter-individual differences in LDL uptake are reflected on all lymphocyte subsets.

Humoral and cellular immune responses in the murine respiratory tract following oral immunization with cholera toxin or Escherichia coli heat-labile enterotoxin

Cholera toxin (CT) and Escherichia coli heat-labile enterotoxin (LT) are the strongest mucosal immunogens identified to date and are also good adjuvants when given orally together in combination with unrelated antigens. We used these potent immunogens to monitor local and systemic immune responses following oral immunization of BALB/c mice, and compared their action on the following: (a) immunoglobulin production rates (IgG, IgM and IgA) in mucosal inductive (Peyer's patches-PPs), effector (intestinal lamina propria-LP, respiratory tract) and systemic (spleen) sites; (b) analysis of systemic antigen-specific antibodies (IgG subclasses, IgA and IgE); (c) time monitoring of fecal anti-CT and anti-LT antibodies, and (d) in vivo relevance of interleukin-6 (IL-6) to mucosal responses. Both mucosal immunogens elicited specific antibody responses (IgA, IgG) not only in the gastrointestinal tract (PP's and intestinal LP), but also in the respiratory tract and spleens of orally immunized mice. These mucosal responses were accompained by elevated secretion of IL-6 in all investigated tissues, indicating involvement of this cytokine in B-cell maturation processes. Furthermore, oral immunization with CT and LT induced elevated serum titers of IgG1 followed by IgG2a, IgG2b, IgG3 and IgA, while high antigen-specific IgA and IgG1 responses were found in fecal extracts. These findings illustrate the action of orally administered CT and LT, respectively, on several humoral and cellular immune responses not only at the gastrointestinal tract, the application site, but also in distant mucosal effector sites such as the respiratory tract. These data suggest the potential use of these mucosal adjuvants in oral immunization strategies to improve the local immune response in remote mucosal tissues, in accordance with the concept of a common mucosa-associated immune system.

Prevention of spontaneous autoimmune thyroiditis in the obese strain (OS) chickens by treatment with a monoclonal anti-CD4 antibody

Untreated control OS chickens develop spontaneous autoimmune thyroiditis (SAT). In contrast, OS chickens treated with a monoclonal anti-CD4 antibody failed to develop SAT. The preventive effect of anti-CD4 antibody on SAT was associated with the marked depletion of CD4+ T-cells by anti-CD4 treatment. These results indicate that CD4+ T-cells play a crucial role in SAT of OS chickens.

Skin allograft survival in chicken strains with spontaneous autoimmune diseases

Skin grafts were performed to prove the level of genetic diversity in chicken populations of the Obese strain (OS), which develops a spontaneous Hashimoto's-like thyroiditis, and University of California at Davis (UCD) Line-200 chickens, which are hereditarily afflicted with progressive systemic sclerosis (scleroderma). As controls, Cornell C-strain (CS) and inbred, normal White Leghorn CB chickens were included in the genetic monitoring program. At the commencement of this study in 1988, median allograft rejections were observed after 9 to 12 d (range 8 to 14 d) in OS and CS chickens that derived from large flocks at Cornell University, whereas OS sublines of the smaller, more closely-bred colonies at the University of Innsbruck, Austria, showed median allograft rejection after 19 d (range 12 to 35 d). From 1988 to 1993, allograft survival was only slightly prolonged in the OS sublines. However, the results of the skin allotransplantations in inbred UCD-200 chickens revealed two subpopulations in this line. In one subgroup the median of allograft rejection was calculated with 13 d (range 6 to 37 d) in 1989, 30 d (10 to 37 d) in 1990, 21 d (8 to 90 d) in 1991, and 16 d (7 to 26 d) in 1993. In the other subgroup allografts were accepted at rates similar to autografts. In addition, the inbreeding coefficient was calculated for eight male and eight female OSB5B5Cornell (C) and OSB5B5Innsbruck (INN) chickens, respectively, hatched in 1993. On the basis of mating records, the minimal estimate of the inbreeding coefficient was calculated to be 0.0679 in the OSB5B5C and 0.1035 in the OSB5B5INN population. The results demonstrated a higher degree of consanguinity in the smaller population of OSB5B5INN chickens compared to OSB5B5C birds. The later are maintained in larger numbers, therefore, the frequency of matings between related individuals should be lower.

Coexpression of heat-shock protein 60 and intercellular-adhesion molecule-1 is related to increased adhesion of monocytes and T cells to aortic endothelium of rats in response to endotoxin

Bacterial cell-wall lipopolysaccharide (LPS) is the main endotoxin contributing to local inflammation and systemic toxicity during Gram-negative infections and induces aortic endothelial injury with or without cell death and replication followed by increased leukocyte adhesion. Heat-shock protein (hsp) 60 is under study in our laboratory as a potential antigen inducing immunologic attack to endothelial cells in atherogenesis. To investigate the mechanism of LPS-induced endothelial injury and the phenotypes of adhering cells, Lewis rats were treated in vivo or, in aortic organ cultures, with LPS to determine the expression of intercellular-adhesion molecule-1 (ICAM-1) and hsp60 on aortic endothelium and to characterize phenotypes of adhering leukocytes. Increased ICAM-1 expression by aortic endothelium was observed as early as 3 hr after LPS injection and persisted up to 72 hr, whereas elevated levels of hsp60 were found between 6 and 48 hr. In vitro application of various types of stress, such as LPS, H2O2, and high temperature, not only stimulated endothelial expression of hsp60 but, concomitantly, that of ICAM-1. The number of adhering leukocytes was significantly increased on aortic endothelium 6 hr after LPS administration, and the predominant leukocytes adhering to stressed endothelium were monocytes (80%) and T lymphocytes (8 to 20%). In organ cultures of rat aortic intimal, LPS, and H2O2 evoked increased leukocyte adhesion, which proved to be selective, because adherent leukocytes were mostly Ia+ monocytes and T cells, i.e., activated. Adhering T cells were gamma/delta antigen-receptor positive in 8 to 16% after LPS stress, whereas these cells amount to only 2 to 4% of peripheral blood T cells. Blocking of adhesion molecules ICAM-1, LFA-1 alpha, and/or LFA-1 beta reduced adhesion up to 34%. Increased coordinated LPS-dependent expression of hsp60 and ICAM-1 correlates with monocyte and T-cell adhesion to aortic endothelium. These observations may be significant for elucidating the mechanism of the initiating events in the development of atherosclerosis.

Autoantibodies against heat shock protein 60 mediate endothelial cytotoxicity

Stress or heat shock proteins (hsp) are a family of approximately two dozen proteins with a high degree of amino acid sequence homology between different species, ranging from prokaryotes to humans, and are representative of a generalized response to environmental and metabolic stressors. Our previous studies showed increased expression of human hsp60 on endothelial cells of arterial intima with atherosclerotic lesions, and elevated levels of serum antibodies (Ab) against hsp65/60 in subjects with carotid atherosclerosis. To investigate the possible involvement of anti-hsp65/60 Ab in endothelial injury, specific hsp-Ab were isolated from human high titer sera by affinity chromatography and probed on heat-shock human umbilical vein endothelial cells. Purified human anti-hsp65/60 Ab reacted specifically with mycobacterial hsp65, human hsp60, and a 60-kD protein band of heat-shocked endothelial cells. High levels of hsp60 mRNA expression in endothelial cells were found between 4 and 12 h after 30 min treatment at 42 degrees C. In immunofluorescence tests, positive staining of heat-stressed endothelial cells was observed not only in the cytoplasm but also on the cell surface. Furthermore, only heat-stressed, but not untreated, Cr-labeled endothelial cells were lysed by anti-hsp65/60 Ab in the presence of complement (complement-mediated cytotoxicity) or peripheral blood mononuclear cells (antibody-dependent cellular cytotoxicity). Control Abs, including human anti-hsp65/60 low titer antiserum, human Ig fraction deprived of hsp65/60 Ab, and mAbs to Factor VIII, alpha-actin, hsp70, and CD3 showed no cytotoxic effect. In conclusion, human serum anti-hsp65 antibodies act as autoantibodies reacting with hsp60 on stressed endothelial cells and are able to mediate endothelial cytotoxicity. Thus, a humoral immune reaction to hsp60 may play an important role in the pathogenesis of atherosclerosis.

Altered switch in lipid composition during T-cell blast transformation in the healthy elderly

Decreased mitogen responsiveness of lymphocytes during aging correlates inversely with membrane microviscosity, which reflects an altered lipid composition. Therefore, we addressed the question, whether age-related alterations of lipid metabolism affect the switch in lipid composition during formation of blasts. Membrane lipids and fatty acids of peripheral blood lymphocytes from SENIEUR protocol compatible ("healthy") elderly donors (66-77 yr) and young controls (18-30 yr) were quantified after incubation with or without the mitogen phytohaemagglutinin. The blastic change in membrane lipid composition was different for young controls with respect to cholesterol, phosphatidylethanolamine, total phospholipids, as well as several fatty acids. Moreover, the age-related alterations in the switch of membrane lipids and fatty acids were significantly correlated with a decreased mitogen response. Thus, the alterations in membrane reorganization during blast formation of lymphocytes from the elderly point to a disturbed cellular lipid homeostasis with possible impact on the age-related reduction in immune function.

Reference intervals for human peripheral blood lymphocyte subpopulations from 'healthy' young and aged subjects

Some lymphocyte subpopulations change during aging but age-related reference limits from a healthy reference population are still lacking. In this study, we compiled 90% reference intervals for commonly determined lymphocyte subpopulations in 'healthy' (Senieur-compatible) young (20-32 years) and elderly (65-74 years) subjects. The most striking age-related changes included increases in HLA-DR+ T lymphocytes, and the shift in the expression of CD45 isoforms from the CD45RA+CD45RO-to the CD45RA-CD45RO+ subset. Both age-related alterations occurred in the CD4+ as well as in the CD8+ subpopulations and most of them were present in the relative and absolute number of lymphocyte subsets. We compare our data with those from previous investigations on lymphocyte subpopulations from the elderly and comment on useful presentation of reference values.

Atherosclerosis as an autoimmune condition

Atherosclerosis is a multifactorial vascular disorder responsible for the highest rate of mortality in the western world. During the last decades, research on this disease has primarily focused on the role of lipids, which are essential to the formation of lesions in the vascular intima that ultimately leads to clinically apparent atherosclerotic plaques. More recently, several anecdotal findings have indicated the possible involvement of the immune system in the process of atherogenesis. In particular, the appearance of immunocompetent cells as well as humoral antibodies in the intima in the early stages of disease development supports the view of an inflammatory component in this disorder. In addition to the search for lipid-associated antigens that might entail full-blown atherosclerosis, other candidate antigens capable of inducing an immune response in the vascular wall have also been explored. Within the probable group of antigens for immune responsiveness, heat shock protein (hsp) 60/65 became a serious candidate, upon observation that immunization of rabbits with this protein led to arteriosclerotic changes of the aortic intima. In the last few years we have established this rabbit model for immunologic investigations of atherosclerosis and, in parallel, examined the pathogenesis of human atherosclerosis with regard to hsp 60/65 immune reactivity. Currently available data point to an autoimmune induction of early inflammatory arteriosclerotic changes triggered by a cellular and humoral immune reaction to stress-induced hsp 60-expressing areas of the endothelial cells.

Genomic analysis of collagen and endogenous virus loci in the UCD-200 and 206 lines of chickens, animal models for scleroderma

University of California at Davis (UCD) lines 200 and 206 chickens develop a hereditary systemic scleroderma-like connective tissue disease characterized by severe lymphocytic infiltration and excessive accumulation of collagen in skin and internal organs. The immune system seems to play an important role in the development and/or perpetuation of this condition. The main goal of our work with this strain is the investigation of interactions between endothelial cells, lymphocytes, macrophages and fibroblasts leading to the proliferation of the latter and to excessive collagen synthesis and/or deposition. One aim of the present study was to clarify whether UCD-200 and 206 chickens have a defect of collagen genes at the genomic level by means of restriction fragment length polymorphism (RFLP) analysis using non-radioactively labelled cDNA probes specific for chicken alpha 1(I), alpha 2(I), alpha 1(II), alpha 1(III), alpha 1(VI), alpha 2(VI), and alpha 3(VI) (pro) collagens. As in the human disease, no gross alteration at the genomic level of collagen genes has been found, thus providing the UCD-200/206 model to be appropriate for studying the altered collagen metabolism in systemic sclerosis (SSc). In addition to the RFLP analysis of procollagen genes, we investigated the endogenous avian leukosis virus loci (ev) of UCD-200 and 206 chickens by means of Southern blot analysis of Sac I and BamH I digested DNA samples using pRAV-2, a Rous sarcoma virus specific probe, for hybridization. Most UCD-200 and 206 chickens harbour evs 1, 3 and 10 similar to the healthy control UCD-058, but they also contain a novel ev characterized by a 4.2 kb Sac I fragment and a 6.1 kb BamH I fragment, which we would like to designate ev 23. So far, the role of ev 23 in the development of avian scleroderma is unclear; for further analysis classical crossbreeding experiments are necessary and are underway.

In vitro allergy testing needs better standardization--test results from different laboratories lack comparability mostly due to missing effective standards

Correct determination of specific IgE is important for the diagnosis of allergic diseases. Different detection systems are supposed to yield similar results of this standardized parameter. In order to investigate this assumption, 40 sera from allergic patients were sent in eight mailings to 23 laboratories over a 2-year period. Three IgE determinations in each serum had to be performed according to laboratory-specific methods. Whereas 'wrong' results were rare with any of the methods and the overall results to a large degree comparable, sensitivity and specificity seemed to vary considerably between antigens, methods, companies and laboratories. According to our observations, better standardization of test reagents and test methods by the suppliers is essential in order to harmonize the test results and to avoid wrong conclusions. At present, the diversity of techniques that are used for IgE determination leads to quite divergent results, and the allergist has to know that. And finally, the legislator is urged to better control these diagnostic tools, because wrong results may lead to life-threatening situations.

Mononuclear cells isolated from fibrotic skin lesions in avian scleroderma constitutively produce fibroblast-activating cytokines and immunoglobulin M

University of California, Davis line 200 and 206 chickens develop an inherited autoimmune fibrotic disease associated with autoantibodies and other features similar to human scleroderma. Early in life, line 200/206 chickens develop mononuclear cell (MNC) infiltrates in the skin, followed by severe dermal fibrosis and vascular occlusions. Cultured fibroblasts derived from fibrotic skin lesions of line 200/206 chickens display an activated phenotype producing elevated quantities of collagen and glycosaminoglycan (GAG) compared to fibroblasts derived from normal chicken skin. To demonstrate a link between skin mononuclear cell infiltration and fibroblast activation, we cultured MNC isolated from developing fibrotic skin lesions, normal appearing skin, and peripheral blood of line 206 chickens for 24-72 h. Subsequent assay of MNC culture supernatants for effect on the collagen and GAG production of normal chicken skin fibroblasts demonstrated that only fibrotic lesion MNC supernatants contained significant collagen and GAG synthesis stimulatory activity. Both stimulatory activities were constitutively produced, undialyzable, heat and protease sensitive, and coeluted on gel filtration with a M(r) of 24-32 kD. Gel filtration also revealed that fibrotic lesion MNC secrete a protein > 250 kD, which we have identified as immunoglobulin (Ig) M by Western blot analysis. These results demonstrate that skin infiltrating MNC secrete both fibroblast-activating cytokines and IgM and thus they likely play an important role as effector cells in the development of dermal fibrosis and autoantibodies in this avian model of scleroderma.

Preferential TCR V beta 1 gene usage by autoreactive T cells in spontaneous autoimmune thyroiditis of the obese strain of chickens

We studied T cell receptor variable beta (TCR V beta) gene usage by autoreactive T cells in spontaneous autoimmune thyroiditis (SAT) of obese strain (OS) chickens. Chicken alpha beta T cells may express either V beta 1 or V beta 2 genes, the products of which can be recognized by TCR2 and TCR3 monoclonal antibodies, respectively. Selective depletion of V beta 1+ or V beta 2+ T cells in OS chickens was accomplished by repeated injections of TCR2 or TCR3 antibodies into embryonic and 1-3-week-old chickens. The birds were killed at 20 days of age and their spleens and thyroid glands evaluated by immunohistochemistry. We found that V beta 1+ T cells preferentially infiltrated OS chicken thyroid glands. Antibody treatments resulted in a 41% reduction in frequency of V beta 1+, and a 87% reduction of the frequency of V beta 2+ cells in the circulation, and in a profound decrease of the respective T cells in spleens and thyroid glands. Selective suppression of V beta 1+ T cells partially inhibited SAT development in that thyroid-infiltrating cells and destruction of thyroid follicles were reduced by more than 50%. Thyroglobulin autoantibody serum levels were also reduced in V beta 1+ T cell-depleted OS chickens, whereas selective depletion of V beta 2+ T cells did not inhibit SAT development. These findings indicate preferential TCR V beta 1 gene usage by autoreactive T cells in SAT of OS chickens.

Chicken thymic nurse cells: an overview

Thymic nurse cells are multicellular complexes located in the subcortical area of the thymus of all avian, mammalian and amphibian species investigated so far. Since their first description in 1980 many studies have been carried out to characterize their morphological and functional properties. The purpose of this review is to summarize recent morphological as well a functional analyses of chicken thymic nurse cells which suggest a role of these cell complexes in T cell selection.

In vivo LDL receptor and HMG-CoA reductase regulation in human lymphocytes and its alterations during aging

The LDL receptor and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase play primary roles in the regulation of cellular cholesterol metabolism. To investigate the transcriptional regulation of lipid metabolism under physiological conditions ex vivo and its alterations during aging, we analyzed both the activity and mRNA concentration of the LDL receptor and HMG-CoA reductase in freshly isolated lymphocytes from healthy young and elderly donors. Data from fluorescent reverse transcriptase-polymerase chain reaction indicated that not only plasma LDL but also plasma HDL downregulates lymphocyte LDL receptor mRNA. Downregulation by HDL was three times more effective than that by LDL and presumably involved specific HDL binding sites. There was coordinate regulation of HMG-CoA reductase mRNA with LDL receptor mRNA that was independent of plasma lipoprotein concentrations. Despite elevated plasma concentrations of LDL, lymphocytes from elderly donors paradoxically expressed increased levels of the LDL receptor (P = .030) and HMG-CoA reductase mRNA (P = .062). The age-related dysregulation of the LDL receptor was predominantly due to impaired downregulation by plasma LDL rather than by HDL. Thus, not only LDL but also HDL and age significantly influences the transcriptional regulation of the LDL receptor in extrahepatic cells in vivo.

Role of heat shock protein 65/60 in the pathogenesis of atherosclerosis

Investigations in rabbits and humans have provided experimental evidence that autoimmune reactions play a major role in the initial stages of the development of atherosclerosis. These involve the infiltration of the arterial intima with T cells reacting with heat shock protein (hsp) 65/60 and the occurrence of anti-hsp 65/60 antibodies. This early immunologically mediated stage of atherosclerosis is still reversible but if additional risk factors, such as high cholesterol levels, come into effect, severe mostly irreversible lesions develop.

Chronic granulomatous disease assessed by single-cell granulocyte oxidative burst activity

Here we report on a case of chronic granulomatous disease (CGD) in a 3-year-old boy who suffered from severe repeated bacterial infections including multiple liver abscesses. The case is of interest because (1) the disease is very rare (it is the first case of CGD diagnosed at the Clinic for Pediatric Medicine, University of Innsbruck), (2) the diagnosis, based on clinical parameters and the nitrobluetetrazolium test was completed and validated by single-cell measurements of respiratory-burst activity of the patient's granulocytes in a fluorescence-activated cell sorter (FACS), and (3) the applied FACS method, adapted in our laboratory, presents one of the most sensitive and reliable methods to evaluate this aspect of disturbed granulocyte function.

Is atherosclerosis an immunologically mediated disease?

In contrast to general beliefs, recent data from different laboratories have provided evidence that the first stages of atherosclerosis are of an inflammatory nature. Here, Georg Wick and colleagues suggest that an autoimmune reaction against heat shock protein 60 (Hsp60), expressed by endothelial cells in areas that are subject to increased haemodynamic stress, is the initiating event in atherogenesis. Humoral and T-cell-mediated immune responses against Hsp60 have both been demonstrated early in disease. This inflammatory stage, which is reversible and has even been found in children, may progress into fully developed atherosclerotic lesions, displaying all the classical pathohistological and functional consequences, if additional risk factors such as high blood cholesterol levels, smoking and obesity, are present.

Methods for the detection of apoptosis

Apoptosis is central to many basic and clinically oriented investigations, and this article is a brief overview of the most frequently utilized methods for detection of apoptotic cells, including the study of morphology, analysis of DNA degradation, DNA end labeling techniques, flow cytometric analysis, and nuclease assays. Features and advantages of the different methods are discussed.

Surface staining and cytotoxic activity of heat-shock protein 60 antibody in stressed aortic endothelial cells

Heat-shock protein (hsp) expression can be induced by high temperature, exposure to cytokines or oxygen radicals, ischemia, hemodynamic overload, or viral infections. To determine whether surface expression of hsp60 occurs in aortic endothelial cells stressed by high temperature or cytokines, cells from rat aortas were cultivated and stained with several types of monoclonal antibodies against hsp60. Other antibodies, eg, those against intercellular adhesion molecule-1 (ICAM-1), or immune response-associated antigens were also used as controls. Positive staining of endothelial cells on the surface and in the cytoplasm was observed after pretreatment of the cells with cytokine-containing medium, tumor necrosis factor-alpha (TNF-alpha), or interleukin-1 alpha and labeling with a specific monoclonal antibody against hsp60 (II-13). Fluorescence-activated cell sorter analyses showed that over 80% of living endothelial cells stressed by cytokine-containing medium, by TNF-alpha, or at 42 degrees C, but not by interleukin-1 alpha, were positively surface stained with this antibody. Increased intensity of immunostaining with antibodies to ICAM-1 and immune response-associated antigen was also seen on the cytokine-stressed endothelial cells. Furthermore, when TNF-alpha stimulated endothelial cells labeled with 51Cr were incubated with antibody II-13 in the presence of complement, significant lysis occurred. In summary, endothelial cells stressed by high temperature or certain cytokines, eg, TNF-alpha, express hsp60 in the cytoplasm and on their surfaces, and these cells were susceptible to complement-dependent lysis by hsp60-specific antibody. These observations may be significant for elucidating the mechanisms of the involvement of immune reactions to hsp65/60 in initiating atherosclerosis.

The suitability of human chorionic gonadotropin (hCG)-based birth-control vaccines

It has been widely hoped that immunological methods of fertility regulation by active immunization against specific antigens of the oocyte, sperm, zygote and early embryo, and the placental pregnancy hormone human chorionic gonadotropin (hCG), will provide a means to control the problem of worldwide population growth. The most advanced candidate vaccines are based on hCG immunogens and have entered clinical trials. However, during the past few years, increasing evidence has emerged that the current approaches using hCG as the target molecule may have some major drawbacks. On the basis of their recent findings, Stephan Dirnhofer and colleagues raise doubts on the suitability, safety and efficacy of gonadotropin-based immunological contraceptive vaccines.

Interleukin-1 receptor deficiency in brains from NZB and (NZB/NZW)F1 autoimmune mice

Interleukin-1 receptors (IL-1R) are expressed in the brain and the anterior pituitary of normal mice (C3H/He, Swiss), and appear to be involved in the neuroendocrine control of the immune response. Here we have studied the IL-1R density in the brain and the pituitary from several strains of autoimmune mice (NZB, (NZB/NZW)F1, MRL/MP-lpr), using quantitative autoradiography with recombinant human [125I]IL-1 alpha as a ligand. IL-1R was similar in the brain of C3H/He, Swiss and NZW (controls) and MRL/MP-lpr mice. In NZB mice a profound deficit (10% of control mice) in IL-1R was observed exclusively in the dentate gyrus. In (NZB/NZW)F1 the deficit was about 50%. These observations were independent of sex and age. Pituitary receptors were not affected in all the strains except NZW (30% increase). Competition experiments demonstrated that the affinity of IL-1R was not modified in dentate gyrus of (NZB/NZW)F1 and NZW mice. Thus, the number of IL-1R was the only parameter affected. This deficit was not reversed by corticosterone treatment (0.2 mg/20 g body weight, i.p.) and was poorly modified by lipopolysaccharide treatment (0.1 mg/20 g body weight, i.p.) compared to C3H/He mice. In conclusion, this central IL-1R deficit is unlikely to be the consequence of occupancy by abnormal synthesis of brain IL-1. This abnormality is tissue-specific with hereditary autosomal transmission. The role of central IL-1R in neuroimmunoendocrine interactions and in autoimmunity remains to be clarified.