[Asbestos content in bronchoalveolar lavage fluid]

The concentration and size distribution of bronchoalveolar lavage (BAL) asbestos fibers (AF) longer than 2 microns was determined by analytical transmission electron microscopy (TEM). The concentration of asbestos bodies (AB) was measured by TEM and light microscopy (LM). The study group consisted of 110 patients. 27 patients had no occupational asbestos exposure, 44 patients had occupational exposure to asbestos but no asbestos related disease and 39 patients had asbestos related diseases, either asbestosis (n = 34) or malignant mesothelioma of the pleura (n = 5) following long time asbestos exposure at the working place. Occupational asbestos exposure was reflected by increased asbestos fiber concentration in the BAL samples. Mean fiber concentration and size was different between the groups, but the scatter was large.

Correlation of lymphocyte lipid composition membrane microviscosity and mitogen response in the aged

Healthy aged and young blood donors were investigated for the role of membrane lipid composition in the age-related increase in membrane microviscosity and decline of mitogen responsiveness. Membrane microviscosity was shown to correlate positively with membrane cholesterol/phospholipid molar ratios, which were significantly elevated in the elderly. A positive correlation also was confirmed between lymphocyte membrane microviscosity, which was measured using the probe 1,6-diphenyl 1,3,5-hexatriene, and phytohemagglutinin responsiveness of cells from the same donor. Using stepwise regression statistical analysis, the variables age, cholesterol, cholesterol/total phospholipid and phosphatidyl ethanolamine/phosphatidyl choline molar ratios were all shown to have a significant positive influence on membrane microviscosity, whereas total phospholipids had a negative effect. No statistically significant difference was seen in content of any single saturated or unsaturated fatty acid between young and old donors. After pooling, however, the proportion of all unsaturated fatty acids was significantly higher in cells from the elderly as a consequence of an increase of n-6 and n-3 polyunsaturated fatty acids. Changes in lipid composition and physical properties of lymphocyte plasma membranes may, therefore, be responsible (at least partially) for the diminution of immune reactivity in old age.

Twelve of fourteen surface epitopes of receptor-bound human chorionic gonadotropin (hCG) being antibody-inaccessible suggest an extensive involvement of the long extracellular domain of the hCG receptor

On the surface of the free (receptor-unbound) form of hCG, we have previously identified 14 topographically distinct epitopes (Schwarz et al. (1986) Endocrinology 118, 189-197; Berger et al. (1990) J. Endocrinol. 125, 301-309). Here we report that only two of them, i.e. the (adjacent) beta 3 and beta 5 epitopes, can be recognized by 125iodine-labeled monoclonal antibodies when hCG was specifically bound to the rat testis hCG receptor. The exclusive accessibility of precisely these two surface epitopes indicates that hCG assumes a defined rather than a stochastic orientation in its receptor-bound state. The inaccessibility of 12 of 14 epitopes is consistent with the idea that the 341 residues long extracellular domain of the recently cloned hCG receptor (MacFarland et al. (1989) Science 245, 494-499) is the ligand binding domain. It is proposed that the extracellular domain is folded in a way that a cavity is formed large enough to accommodate hCG. Thereby, a considerable portion of the total surface of hCG is covered, as reflected by the masking of most of its epitopes.

Number and topography of epitopes of human chorionic gonadotropin (hCG) are shared by desialylated and deglycosylated hCG

A previously established map of the surface epitopes of human chorionic gonadotropin (hCG) served as template for the present study in which we investigated the antigenic surfaces of two glycosylation variants of hCG, i.e. desialylated hCG (asialo-hCG) and deglycosylated hCG (degly-hCG). This map allocates five epitopes to the alpha subunit, five to the beta subunit and four alpha beta epitopes to structures formed only by the alpha/beta heterodimer holo-hCG (Schwarz et al. (1986) Endocrinology 118, 189-197; Berger et al. (1990) J. Endocrinol. 125, 301-309). Here it is described that both variants complied with this template: each of the 14 distinct monoclonal antibodies with which the epitopes of hCG were defined reacted with radiolabeled asialo-hCG and degly-hCG as well and generally bound degly-hCG with greater affinity than hCG. Moreover, every combination of capture and radiolabeled detection antibody that was either compatible or incompatible on unlabeled hCG was so also on unlabeled asialo-hCG and degly-hCG. It thus appears that alterations of the carbohydrate structure of hCG can be associated with a change in affinity between some antibodies and their respective epitopes but not with a loss of an epitope or with a change in the topographical relationships of the 14 epitopes.

Phenotypic analysis of skin infiltrates in comparison with peripheral blood lymphocytes, spleen cells and thymocytes in early avian scleroderma

University of California at Davis line 200 (UCD-200) chickens develop a hereditary connective tissue disease characterized by severe lymphocytic infiltration, vascular occlusion and fibrosis of skin and internal organs. To identify cellular immunological abnormalities in the acute inflammatory disease stage of this animal model for progressive systemic sclerosis (PSS) we investigated the phenotypic characteristics and function of peripheral blood lymphocytes (PBL), spleen cells and thymocytes in comparison with skin infiltrating cells. Immunofluorescence and immunohistochemical analysis using monoclonal antibodies revealed the overwhelming majority of skin infiltrating mononuclear cells in the deeper dermis and subcutaneous tissue to be T cell receptor alpha/beta (TcR2)+/CD3+/CD4+/class II+ cells, a small portion (5-10%) of which were interleukin 2 (IL-2) receptor positive. In contrast, the inflammatory infiltrate in perivascular areas of the papillary dermis was constituted of mainly TcR gamma/delta (TcR1)+/class II- lymphocytes. Only few B cells (T/B cell ratio greater than 5) were detected. These diseased chickens showed significantly reduced percentages and numbers of circulating peripheral T cells exhibiting TcR1, TcR2, CD3, CD4 or IL-2-receptor, probably owing to an increased influx into lymphoid organs and affected tissues. In contrast to healthy chickens, the thymi of UCD-200 animals revealed fewer cells expressing TcR1, TcR2 and class II antigen, suggesting an altered intrathymic maturation of the T cell lineage. Functional in vitro studies showed a significantly decreased T cell mitogen-induced proliferation rate associated with a decreased capacity to produce IL-2 and to express IL-2 receptors. In contrast to the deficient in vitro IL-2 production the sera of UCD-200 chickens contained significant levels of IL-2 bioactivity. The alteration of T lymphocyte physiology in UCD-200 chickens adds, at least in part, to the parallels between this animal model and its human counterpart. These data confirm our hypothesis that the PSS-like disease of UCD-200 chickens includes a numeric and/or functional alteration of peripheral T cell subsets, especially of TcR1 positive cells, in contrast to the pronounced accumulation in the afflicted tissues.

Epitope mapping of the receptor-bound agonistic form of human chorionic gonadotropin (hCG) in comparison to the antagonistic form (deglycosylated hCG)

On the surface of free human chorionic gonadotropin (hCG), we can distinguish with our panel of monoclonal antibodies (MCA) 14 topographically distinct epitopes (designated alpha 1 - alpha 5, beta 1 - beta 5, alpha beta 1 - alpha beta 4, depending on the subunit they are attached to). Only 2, i.e. the adjacent beta 3 and beta 5 epitopes, of these 14 are accessible to 125I-labeled MCA binding, when hCG is first allowed to bind to the rat testis hCG receptor. This result indicates that the agonist hCG assumes a defined orientation in its receptor-bound state and that, except for that small area comprising the beta 3 and beta 5 epitopes, most of its surface is masked by the hCG receptor. We therefore asked whether the competitive antagonist deglycosylated hCG (degly-hCG), which, when free, is antigenically (as to number and topography of epitopes) indistinguishable from native hCG, would interact with the receptor differently, that is, in a way that can be discerned by this epitope accessibility paradigm. Here we describe that on receptor-bound degly-hCG the beta 3 and beta 5 epitopes were concealed as were all other epitopes. This observation, together with finding the receptor affinity of degly-hCG to be 4 times higher than that of native hCG, suggests that degly-hCG assumes a signal transduction-incompetent ligand orientation and at the same time interacts with the receptor more intensively, i.e. establishes additional ("antagonist accessory") protein-protein contacts besides those involved in agonist binding. It thus appears that the carbohydrate moieties function to prevent formation of such accessory contacts.

In-vivo treatment with 5-azacytidine causes degeneration of central lymphatic organs and induces autoimmune disease in the chicken

In-vitro evidence suggests that DNA methylation may be involved in the development of forbidden immune responses that can result in autoimmune disease. In the present study we examined in-vivo effects of 5-azacytidine (5-azaC), a substance that inhibits DNA methylation, on the immune system and the occurrence of a spontaneous autoimmune disease in the chicken model. We found that (1) treatment of young normal chickens with 1.0 mg/kg 5-azaC on 7 consecutive days caused a rapid degeneration of the central lymphoid organs thymus and bursa; (2) this regimen with 5-azaC apparently inhibited B cell maturation, as the frequency of cytoplasmic Ig+ plasma cells in the bone marrow was found to be significantly reduced, whereas the total number of bone marrow cells was unchanged; and (3) a chronic low-dose (0.5 and 1.0 mg/kg) application of 5-azaC through 6 weeks was found to significantly enhance the spontaneous autoimmune thyroiditis in newly hatched chickens of the Cornell C strain, as determined by anti-thyroglobulin autoantibody titres and histological analysis of thyroid gland infiltration. The possible implications of these data for the generation of pathogenic autoimmune responses are discussed.

Expression of class II-MHC antigens in the dermis of patients with progressive systemic sclerosis

Expression of class II major histocompatibility complex (MHC) antigens on normally negative cell types may convert them into effective antigen-presenting cells. It was therefore of special interest to elucidate whether the main cell populations involved in progressive systemic sclerosis (PSS) express class II antigens on their surfaces and participate in the initiation and/or perpetuation of a cellular immune response in the connective tissue. Immunofluorescence studies on frozen skin sections of scleroderma patients using double-staining techniques revealed a pronounced dermal mononuclear cellular infiltrate with signs of activation manifested by expression of MHC class II antigens in the acute phase of the disease. Most endothelial cells of the papillary and deeper dermal vessels were class II-positive as seen in other inflammatory dermatoses. Moreover, class II antigen-positive fibroblasts were found, especially in the deeper dermis within infiltrated areas around blood vessels. MHC class II molecules were also detected in higher density and on increased numbers of perivascular dermal dendrocytes. On all cell types, HLA-DP was much less frequently expressed than HLA-DR, but more frequent than HLA-DQ. However, in the chronic phase of the disease, with reduced inflammation and increasing sclerosis, MHC class II antigen expression on dermal fibroblasts was again diminished or even absent, as seen in normal and non-PSS inflammatory control biopsies and clinically unaffected skin of scleroderma patients in the acute inflammatory disease stage. Our data speak against a primary expression of class II molecules on PSS-fibroblasts. It seems more likely that Ia-antigens on fibroblasts and an increase of MHC class II positive dermal dendrocytes are induced in an early stage of the disease, i.e., after the influx of the mononuclear infiltrate, most probably by mediators released from these cells. Since an enhanced transcription rate of collagen genes in fibroblasts surrounded by infiltrating cells has been described, this early expression of class II MHC antigens does not seem to play a central role in the induction phase, but rather, may be important in the perpetuation of fibrotic processes in scleroderma.

Relationship of orientation with affinity and activity of receptor-bound glycosylation variants of human chorionic gonadotropin (hCG), as visualized by monoclonal antibodies (MCA)

When hCG was receptor-bound, only 2 epitopes (i.e. beta 3 and beta 5) out of its previously mapped total of 14 surface epitopes (10, 11, 12) could be detected by the respective 125I-MCA. Clearly, this indicates a non-random orientation of hCG in this particular state (1). Now we report that on receptor-bound desialylated (asialo-hCG) as well as on receptor-bound deglycosylated hCG (degly-hCG), the beta 3 and beta 5 epitopes were inaccessible for 125I-MCA as were the remaining epitopes, although both variants, when not receptor-bound, were indistinguishable from native hCG with respect to number and topography of epitopes. Thus, the carbohydrate (CHO) units of hCG neither seem to be part of these 14 antigenic sites nor to contribute to the affinity of receptor binding: both variants had even higher affinities than native hCG. However, since the CHO are known to be obligatory for triggering the postreceptor responses of hCG-stimulated target cells, as seen by the 50% reduced or totally abolished biological potency of asialo-hCG and degly-hCG, respectively, the here demonstrated clear-cut differences in epitope accessibility can be related to differences in receptor-bound orientations which reflect signal transduction-competent and incompetent modes of interaction with the receptor. We believe that the CHO, while not contributing to receptor binding per se, function to assure correct positioning of hCG in the ligand recognition domain to allow for proper protein-protein interactions between ligand and receptor and thus optimal activation and hence transduction of the external signal to the cell's interior. In addition, the fact that most of the surface epitopes were masked on receptor-bound hCG, represents the first experimental support for the sofar unproven hypothesis that this unusually long (i.e. 341 amino acid residues) extracellular N' terminal domain of the recently cloned hCG receptor (hCG-R) (23,24), is indeed involved in ligand recognition.

Lipoprotein interactions with T cells: an update

The role of plasma lipoproteins in atherogenesis is well recognized but the physiological relevance of their immunoregulatory properties is still questioned. Here Karine Traill and colleagues outline the recent advances that have been made towards unravelling the mechanisms of immunoregulation by lipoproteins in vitro and consider whether any of these mechanisms are operative in vivo. In particular they address the possible detrimental effects of high serum lipoprotein levels on immune function and the question of whether hyperlipidemia (or hypercholesterolemia) should be considered a risk factor for diminished immunity, for example in old age.

Molecular analysis of genetically determined target organ abnormalities in spontaneous autoimmune thyroiditis

We have shown in earlier studies, that the development of spontaneous autoimmune thyroiditis (SAT) in chickens of the Obese strain (OS) depends on the presence of both, two dominant genes coding for an altered immune regulation and one recessive gene responsible for the susceptibility of the target organ for the autoimmune attack. The product(s) of the latter is (are) still not known. The present study was aimed at identifying possible candidates of cellular components of the thyroid gland of OS chicken and its SAT susceptible parental Cornell C-strain (CS) by high resolution 2-dimensional (2D) gel electrophoresis. For this purpose organ cultures of the thyroid, bursa, thymus and liver were established and the synthesized polypeptides were labelled by 35S-methionine. OS and CS organs were compared with those of healthy normal White Leghorn (NWL) controls. The autoradiographs of the 2D-gels obtained from individual samples after various labelling periods were subjected to comparative analysis. We have found both quantitative and qualitative differences of polypeptide spots between OS/CS and NWL organ samples, some of them specific for the thyroid gland. Although one has to be aware that in this multidimensional analytical approach numerous, still elusive pattern differences are revealed, the thyroid specific phenomena will be further scrutinized.

Analysis of the immune-encodrine feedback loop in the avian system and its alteration in chickens with spontaneous autoimmune thyroiditis

In both mammals and chickens, immunization with exogenous antigens results in a surge of serum glucocorticoid hormone levels concomitant with the antibody response. This effect is mediated by glucocorticoid-increasing factors (GIF) produced by cells of the immune system. In the avian system, GIF appear to act via the hypothalamo-pituitary axis and not directly on the adrenal gland. Interleukin 1 is the main active substance responsible for GIF activity, as shown by molecular sieve and immunoaffinity chromatography studies. In contrast to data from mammals, we found no evidence that interleukin 2 elevates chicken corticosterone. Obese strain chickens with spontaneous Hashimoto-like autoimmune thyroiditis are deficient in their in vivo GIF response. Because no differences were found between autoimmune and healthy chickens in the corticosterone response of the adrenal gland after ACTH administration, and since autoimmune animals are able to react normally to immobilization stress, it is assumed that this deficiency is due to a specific defect rather than a general disturbance in the endocrine system.

Immunology of atherosclerosis: cellular composition and major histocompatibility complex class II antigen expression in aortic intima, fatty streaks, and atherosclerotic plaques in young and aged human specimens

There is evidence that fatty streaks in arteries can transform into atherosclerotic plaques. Mononuclear cells, including both monocytes and lymphocytes, are among the first cells participating in the development of atherosclerosis of experimental animals. To investigate the roles of different cell types in human atherosclerosis, we enumerated and compared the cellular compositions of normal intima, the transition zone (the area between the normal intima and the core of fatty streaks), fatty streaks, and plaques in young (age 16-30 years) and aged (over 60 years) human specimens using double-staining immunofluorescence with a series of monoclonal and polyclonal antibodies. T lymphocytes, both T helper/inducer (70% of T cells) and T suppressor/cytotoxic (30%) phenotypes, were found in every stage of atherosclerosis, constituting 30 to 40% of total cells in fatty streaks and transition zones of young subjects, and occasionally even in normal intima. Seventy percent of these T cells were HLA-DR positive, which indicated that most of them were activated. Macrophages were most frequent in fatty streaks and around the necrotic core of plaques. Smooth muscle cells, increasing from 5 to 30% with lesion progression, were HLA-DR positive where activated T helper cells occurred in the vicinity. The intracellular presence of the invariant gamma chain confirmed that HLA-DR was actually synthesized by these smooth muscle cells. Endothelial cells were HLA-DR positive above those regions of the lesions where HLA-DR-positive cells had accumulated, but not in normal intima, again suggesting induction of HLA-DR expression by T-cell-derived gamma-interferon. Furthermore, most HLA-DR-positive cells were also identified as HLA-DP and HLA-DQ positive. This aberrant major histocompatibility complex class II antigen expression in smooth muscle and endothelial cells may participate in the perpetuation of the atherogenetic autoimmune reaction.

Intrathymic nurse cell lymphocytes can induce a specific graft-versus-host reaction

Single chicken thymic nurse cells (TNC) placed onto the chorionallantoic membrane (CAM), showed that intra-TNC lymphocytes (TNC-L) possess a strong graft-versus-host reactivity (GVHR) in allogeneic MHC combinations. This reaction shows the morphological, phenotypic, and functional characteristics of a classical GVH reaction (GVHR). The induction of a GVHR was significantly higher for TNC-L as compared with thymocytes or peripheral blood lymphocytes (PBL). The specificity of the GVHR was shown by serial transfer experiments onto appropriate allogeneic and syngeneic secondary embryonic hosts. In immunofluorescence analyses with monoclonal antibodies (mAb) to the chicken alpha/beta and gamma/delta T cell receptors (TCR) and the CD3, CD4, and CD8 equivalents, an enrichment of CD3+/CD4+/CD8- and CD3+/CD-4-/CD8+, TCR-alpha/beta + and TCR- gamma/delta + cells was observed inside TNC as compared with extra-TNC thymocytes. A large proportion of CD4+ and/or CD8+ TCR- gamma/delta + cells were demonstrated inside TNC. A minor population among TCR- gamma/delta extra-TNC thymocytes also expressed CD4 and/or CD8 molecules. Based on functional tests and double staining experiments, we propose that CD4+/CD8+ thymocytes enter the TNC where they may undergo positive selection for MHC restriction and further differentiation to CD4 or CD8 single-positive cells. Taken together these data support the concept that TNC contribute a specialized thymic microenvironment for T cell differentiation and maturation.

[Monoclonal antibodies to non-assembled alpha and beta chain of human chorionic gonadotropin (hCG)]

Using a panel of monoclonal antibodies (MCA) to human chorionic gonadotropin (hCG) and its alpha and beta subunits and additional MCA to the non-assembled, free alpha and beta chains which were produced in the course of the present experiments, it was possible to extend the previously established epitope map of hCG. Two MCAs turned out to be specific for the free alpha chain of the glycoprotein hormones (GPH) and, thus, did not react with holo hCG. Two other MCA recognized two epitopes (beta 6 and beta 7) on the free form of the hCG beta only. Again, no holo hormone cross-reaction was observed. Whereas previously only nine antigenic hCG determinants (3 alpha, 4 beta, 2c) had been demonstrated, it was now possible to distinguish fourteen epitopes (5 alpha, 5 beta, 4c). In addition, epitope maps were established for the non-assembled, free subunits of hCG. These comprise six epitopes on the alpha chain (alpha 1- alpha 6) and seven on the beta chain (beta 1- beta 7). Both so far generally accepted premises of Judith Vaitukaitis, claiming the beta chain of the GPH to be immunologically species-specific, the beta chain to be immunologically hormone-specific, were clearly disproven by demonstrating inter- and intra-species cross-reaction of some MCA. Based on the immunological topography of the holo hCG molecule and its free subunits, highly specific and sensitive immuno-enzymometric assays (IEMA) with predictable specificities were designed, measuring either non-assembled subunits alone or in combination with the intact hormones.

Monoclonal antibodies against the free subunits of human chorionic gonadotrophin

Discordant results on body fluid levels of human chorionic gonadotrophin (hCG) free alpha- and beta-subunits under physiological and pathophysiological conditions, prompted us to raise a total of 260 monoclonal antibodies (MCA) against free hCG-alpha, free hCG-beta, holo-hCG, human follicle-stimulating hormone and bovine luteinizing hormone; 153 MCA recognizing the human alpha-subunit and 28 reacting with hCG-beta were extensively analysed for their intra- and inter-species cross-reactivity with homologous hormones, and for the compatibility of epitopes recognized by them. The immunological topography of free hCG-alpha and free hCG-beta was resolved by these MCA, and epitope maps were designed. Six antigenic determinants on the free alpha-chain (alpha 1-alpha 6), clustered in three spatially distinct domains, and seven epitopes on the surface of free hCG-beta (beta 1-beta 7), could be distinguished. Strikingly, three alpha-chain epitopes (alpha 4, alpha 5 and alpha 6) were shared between various species, which is in contradiction to the concept of immunological species-specificity of alpha-subunits. Three determinants were found to be present only on the free subunits but not on holo-hCG (alpha 6, beta 6 and beta 7), and only two determinants (beta 1 and beta 7) were hormone-specific for hCG. Based on this information, an immunoenzymometric assay for the free alpha-subunit of human glycoprotein hormones was established, with a sensitivity of 1.3 pg/well and a cross-reactivity with holo-hCG of less than 0.005%.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcription and expression of transforming growth factor type beta in the skin of progressive systemic sclerosis: a mediator of fibrosis?

Progressive systemic sclerosis is characterized by extensive generalized fibrotic destruction associated with increased accumulation of collagen and other extracellular macromolecules in the skin and other involved organs. It has been suggested that mediators released from mononuclear or endothelial cells play a critical role in the initial activation of connective tissue metabolism. Transforming growth factors beta(TGF-beta 1, TGF-beta 2) mediate the inhibition of epithelial cell proliferation and the induction of fibronectin and collagen gene expression. Therefore, we investigated the distribution of both TGF-beta 1 and TGF-beta 2 mRNA and the final proteins in PSS skin in comparison with other inflammatory dermatoses and healthy controls by means of in situ hybridization and immunohistochemistry. Our studies revealed TGF-beta 1 and -beta 2 mRNA in dermal and subcutaneous infiltrating cells in both acute and chronic PSS, but also in the other inflammatory skin disorders. In the vicinity of this infiltrate single TGF-beta positive fibroblasts could be found in acute PSS. The cytoplasm of epithelial cells of all skin adnexa showed TGF-beta transcripts and no apparent differences were seen in the distribution and number of autoradiographic grains between diseased and healthy skin samples. Especially, we could demonstrate abundant expression of TGF-beta 1/2 in epithelial hair follicle cells of the outer root sheath. Generally, the expression of TGF-beta 2 was less abundant than TGF-beta 1. Immunohistochemical studies revealed the same distribution pattern of the final proteins. Our data indicate that TGF-beta expression in infiltrating cells is not a specific feature of fibrotic disease, but seems to be associated with highly proliferating cells in general, perhaps functioning as common mediator in regulation of cellular physiology with special importance for negative control of cell growth.

Increased expression of high-affinity low-density lipoprotein receptors on human T-blasts

Like all cells, lymphocytes need cholesterol for proper function, a requirement met by a finely tuned homeostasis between intracellular synthesis and uptake from the environment via low-density lipoproteins (LDL). We used flow cytometry to analyze the receptor activity of resting cells and T blasts incubated/activated in serum-free culture medium, or in medium supplemented with 25-5,000 micrograms/ml LDL. Dioctadecyl-indocarbocyanine has proved to be a useful fluorescent probe for investigating the LDL receptor activity of lymphocytes. The results show the receptor activity of day-3 resting T cells to be reduced more than 50% by 50 microgram LDL/ml, whereas 100-fold higher concentrations are necessary to achieve the same level of reduction in day-3 PHA blasts. The LDL receptor activities of individual blood donors' resting T cells, in vitro cholesterol-deprived resting T cells, and activated T blasts, were compared using two analytical techniques: spectrofluorometric analysis of detergent-solubilized cell suspensions and flow cytometric analysis of single living cells. Receptor affinity was determined by Scatchard analysis of spectrofluorometric binding curves, and by Line-weaver-Burke plots of flow cytometric data. Both methods yielded essentially identical dissociation constants (Kd) for cholesterol-deprived resting T cells and mitogen-activated T blasts, which fell in the expected range for the high-affinity LDL receptor (4.1-8.9 nM). In addition, spectrofluorometric analysis, but not flow cytometry, permitted quantification of LDL uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

An orally administered bacterial immunomodulator primes rabbit neutrophils for increased oxidative burst in response to opsonized zymosan

To assess the potential effect of an orally administered immunomodulator, consisting of a lysate of seven different bacteria, on polymorphonuclear leukocyte (PMN) function, rabbits were fed this preparation for five consecutive days via a gastric tube. On day 6, PMN were separated from peripheral blood and oxidative burst was triggered by opsonized zymosan or 12-O-tetradecanoylphorbol-13-acetate and quantitated on a single-cell basis. This study presents the extension of an existing flow cytometric method, leading to the possibility of quantitating single-cell oxidative burst triggered by particulate (instead of only soluble) stimuli. By this means, treated animals showed statistically significant increased oxidative burst reactions compared with the control group. The data provide evidence that oral application of a bacterial immunomodulator leads to a primed state in PMN for increased oxidative activity in response to a particulate stimulus. This offers the possibility that the beneficial effect of similar treatment in humans may in part be due to comparable mechanisms.

Use of a FACS III for fluorescence depolarization with DPH

We have previously demonstrated age-related differences in human lymphocyte membrane fluidity, by use of steady-state polarization measurements on bulk cell suspensions with the fluorescence probe DPH. However, for exact analysis of the possible functional importance of these changes, single-cell measurements were deemed of interest. We have now used an analog division device to measure fluorescence depolarization "p" of DPH in real time with a FACS III flow cytometer. The measurements are reliable, as we have been able to confirm the differences in DPH "p" between monocytes and lymphocytes previously shown in bulk suspension and to demonstrate the expected differences in fluidity of lipid-modulated cells. We also found significant differences in DPH "p" between lymphocytes of young and elderly blood donors. Lymphocyte subsets did not differ in polarization values but did differ in fluorescence intensity with Th less than Ts less than B = NK cells.

Immunogenetic analysis of spontaneous autoimmune thyroiditis of obese strain chickens

A variety of immunological, endocrinological, and virological abnormalities have been implicated in the etiopathogenesis of spontaneous autoimmune thyroiditis (SAT) of Obese strain (OS) chickens, e.g., a general T cell hyperreactivity, an increased uptake of iodine into the thyroid gland, a diminution of the glucocorticoid tonus, and an OS-specific endogenous virus. In crosses of the close-bred OS B15/B15 subline with the inbred normal CB B12/B12 strain we have studied the mode of inheritance of these aberrations and their putative association with SAT. The results indicate that none of these OS-specific characteristics alone is an absolute prerequisite for the development of thyroid infiltration, which appears to be governed by one autosomal recessive gene.

Promotion of lymphocyte growth by high density lipoproteins (HDL). Physiological significance of the HDL binding site

The characteristics and physiological relevance of the high density lipoprotein (HDL) binding site on unstimulated and mitogen activated human peripheral blood lymphocytes have been investigated. At 37 degrees C, specific binding/uptake of fluorescent (dioctadecylin-docarbocyanine, DiI) HDL was observed by cells from healthy donors as well as by those from low density lipoprotein receptor-defective patients; mitogen activated T-blasts exhibited a markedly elevated DiI-HDL uptake compared to resting T-cells. Binding was saturable at 37 degrees C and of high affinity, with a Kd of 5 x 10(-8) M. It was blocked by anti-apoAI polyclonal antibodies (F(ab)2 fraction), but not by anti-apolipoprotein (apo)E, anti-apoAII, or anti-apoB, and was inhibited competitively by HDL apoproteins and an apoAI-protein A fusion protein. T-cell associated DiI-HDL was increased by trypsin treatment (of the cells) and decreased by activation in the presence of HDL or low density lipoprotein. Comparison of the concentration dependencies of growth promotion and specific cell association of HDL indicated that two mechanisms of lipid exchange may be in operation: one a binding-dependent mechanism of cholesterol exchange, with maximal effect in the HDL concentration range (20-200 micrograms/ml) in which specific binding increases rapidly, and the other a binding-independent exchange of lipids effective at concentrations in which specific binding is saturated (300-5000 micrograms/ml).

[Molecular genetic analysis of autoantibody production in systemic lupus erythematosus]

This review summarizes studies from our and other laboratories attempting to define the molecular and clonotypic origin of autoantibodies that typify systemic autoimmune diseases such as lupus and rheumatoid arthritis. Comparative restriction fragment length polymorphism (RFLP) studies investigating the immunoglobulin (Ig) germline gene organization in lupus-prone strains of mice suggested that the disease can develop in different Ig heavy (H) and light (L) chain haplotypes, and that the Ig germline genes in lupus mice are probably normal. Analysis of the Ig gene segments expressed in monoclonal autoantibodies from autoimmune mice revealed that similar, and in some instances even identical, gene segments are expressed in autoantibodies and in antibodies to exogenous antigens, and that anti-self and anti-non-self responses are encoded by the same, or at least an overlapping germline gene repertoire. A large variety of Ig variable (V), diversity (D), and joining (J) gene segments can encode autoantibodies with different specificities, and both germline genes and somatically-mutated genes can be expressed in such antibodies.

Approach to define "normal aging" in man. Immune function, serum lipids, lipoproteins and neopterin levels

In 53 healthy women with mean age 25.1 years (age range 21-34 years) and in 51 healthy women with mean age 82.1 years (age range 75-91 years), a panel of immunological and biochemical tests was performed. These tests, comprising lymphocyte mitogen responsiveness, phenotyping of lymphocytes, uptake of low density lipoprotein by T cells, serum levels of neopterin, lipids and lipoproteins, as well as routine blood chemistry, were investigated for a possible effect of age and of the classification according to the SENIEUR Protocol of admission criteria by the European Economic Community's Concerted Action Program on Aging (EURAGE). A highly significant effect of age on serum levels of neopterin, lipids and lipoproteins was found. No clear effects, however, of SENIEUR status on these variables was detected. As expected, age had a significant impact on mitogen responsiveness of T cells. Proportional numbers of helper/inducer and cytotoxic/suppressor T cells (as well as antigen density on these cells) were not influenced by age. SENIEUR classification did not affect these immunologic variables. Thus, most of the tested variables that are not included in the SENIEUR admission criteria appear to present information not yet covered by the SENIEUR variables. Various ways for a possible revision or extension of the SENIEUR Protocol are discussed.

Antigenic features of human follicle stimulating hormone delineated by monoclonal antibodies and construction of an immunoradiomometric assay

The characterization of human (h) FSH with 181 monoclonal antibodies (MCA) allowed the elucidation of its antigenic topography. One- and two-site, limited as well as excess reagent type radioimmuno- and enzymoimmunoassays revealed three main categories of MCA molecular binding specificities; two thirds of all antibodies were directed against the alpha-subunit and one fourth toward the beta-chain, and less than one tenth recognized the conformationally (c) intact holohormone. With high frequency immunization schedules these specificities were shifted toward a higher proportion of beta-MCA. On the basis of intra- and interspecies cross-reaction studies as well as epitope contiguity analyses by sandwich assays, the three main categories could be further subdivided into nine epitopes: 1) five epitopes associated with the alpha-subunit, two of which were suprisingly shared by other species, and two being iodination sensitive, 2) two evolutionary conserved structures on the beta-subunit, adjacent to each other, and 3) two c-determinants, one of these present also on hTSH. The epitopes were arranged in three major antigenic domains, which seems to be a common homologous construction principle of the four human glycoprotein hormones: a central domain, consisting of three identically arranged alpha- and similarly located c-epitopes, is flanked by a single spatially distinct domain on each subunit. The establishment of an epitope map was followed by the construction of an immunoradiometric assay with a sensitivity of 0.25 ng hFSH/ml and an apparent cross-reactivity vs. hLH, hTSH, and hCG of less than 1%.

Cell cycle control of a Burkitt lymphoma cell line: responsiveness to growth signals engaging the C3D/EBV receptor

CR2, the receptor for the C3d fragment of the third complement component and for Epstein-Barr virus (EBV) has been shown, on mouse B cells, to be involved in the control of B-cell proliferation by acting as a receptor for macrophage-derived growth factors. We examined whether the growth of a Burkitt lymphoma cell line, RAJI, could be influenced by ligands of human CR2. In serum-free culture, purified human C3d, as well as three monoclonal antibodies to distinct epitopes on human CR2, were capable of enhancing the growth rate of RAJI cells two to five-fold. This effect could not be observed if even trace amounts of serum were present in the culture medium. Simultaneous addition of pairs of antibodies did not enhance the growth rate, suggesting that a particular engagement of CR2 may be critical in order to induce a stimulatory effect. These results indicate that in a homologous serum-free human B-cell system human C3d as well as monoclonal antibodies to human CR2 can induce B-cell proliferation and that CR2-mediated triggering of B cells can be induced via epitopes other than the C3d-binding site. In addition we conclude that--unlike normal human B cells--at least some human B-lymphoma cells respond to CR2-mediated stimuli in the absence of any T-cell derived factors. Therefore the control mechanisms exerted through CR2 must still be intact on these autonomously growing cells.

Genetic analysis of extrathyroidal features of Obese strain (OS) chickens with spontaneous autoimmune thyroiditis

The Obese strain (OS) of chickens, which is afflicted with Hashimoto-like spontaneous autoimmune thyroiditis (SAT), displays elevated T cell proliferation, interleukin (IL)2 production and IL2 receptor expression upon mitogen stimulation, and defects in the neuroendocrine control of the immune system including elevated corticosteroid-binding globulin (CBG) and a deficient increase of serum corticosterone (CN) upon cytokine injection. Recently this strain has further been shown to harbor retrovirus-related sequences (endogenous virus no. 22, ev22) absent in healthy control strains. To determine the number of genes responsible for SAT-associated immunodysregulation and to unravel possible ev22 associations, we analyzed the above immune and endocrine parameters in F1 hybrids and backcrosses of the autoimmune OS B15B15 with healthy inbred CB B12B12 chickens. OS-like T cell hyperproliferation and IL2 hypersecretion in response to both concanavalin A and phytohemagglutinin were transmitted as autosomal dominant traits and co-segregated in backcross animals. In vivo hyporesponse of the OS to the corticosterone-inducing effect of cytokine preparations was inherited dominantly and the elevated CBG serum levels recessively. None of these traits appeared to be major histocompatibility complex (MHC) linked. However, while T cell abnormalities and elevated CBG serum levels were not associated with the autosomal ev22 locus, in vivo hyporesponsiveness to glucocortocoid-inducing cytokines co-segregated with this OS-specific provirus. These results add to the concept of SAT as a polyetiological and plurigenetic disease and do not support our previous hypothesis that T cell hyperreactivity and immunoendocrine dysfunction might be functionally related.

ev 22, a new endogenous avian leukosis virus locus found in chickens with spontaneous autoimmune thyroiditis

Chickens of the Obese strain (OS) develop a hereditary spontaneous autoimmune thyroiditis (SAT) which closely resembles human Hashimoto's disease. Analysis of the endogenous viruses harboured by these animals revealed a new endogenous virus (ev22) detected as a 5.5 kb Sac I fragment. Crossbreeding experiments showed that ev22 is vertically transmitted as an autosomal trait not associated with major histocompatibility (MHC) alleles. Preliminary experiments indicate that ev22 does not necessarily cause SAT, however, it may have a modulatory role in the development of the disease.

Improvement of immunofluorescence for diagnosis of AIDS using laser microscopy

One of the most commonly used methods for demonstration of HIV antibodies is indirect immunofluorescence employing HIV-infected, CD4-positive lymphoid cell lines as antigenic substrate. Immunofluorescence with conventional optic equipment is reported to be slightly less sensitive than enzyme-linked immunoassay (ELISA). We have developed an immunofluorescence microscope which is equipped with an argon laser that has the advantages of much brighter fluorescence than conventional techniques, the prevention of fluorescence bleaching, and the possibility of distinguishing specific from nonspecific staining by comparative analysis of the kinetics of the bleaching curves. This microscope has now been used for demonstration of HIV antibodies in indirect immunofluorescence tests on the H9 lymphoid cell line, which is highly efficient in expressing HIV after infection. Titers of ELISA and Western blot-verified HIV-positive patients and appropriate normal controls were compared using four types of microscopic equipment, including the laser immunofluorescence microscope. The latter afforded significantly higher titers than those obtained with conventional immunofluorescence microscopes, and also made possible the distinction between specific and nonspecific staining.

Decreased level of thymidine in the serum of obese strain (OS) chickens with spontaneous autoimmune thyroiditis

We have previously shown that normal chicken serum (NCS) is able to interfere with the IL 2 promoted incorporation of DNA precursors into T lymphoblasts and that serum derived from autoimmunity prone Obese strain (OS) chickens is deficient in this respect. This "defect in non-specific suppression" has been speculated to be one of the causes for T cell hyperreactivity in the OS. In this study we present several lines of evidence that the suppressive effect of normal chicken serum (NCS) on 5-(125Iodo)-2-deoxyuridine (125IUdR) uptake into chicken T blasts is a competition artefact due to cold thymidine (TdR) present in NCS. Inhibition of 125IUdR required the continuous presence of NCS and suppression of 3H-TdR incorporation could be competed for by increasing the dose of the radiolabel. Molecular sieve chromatography followed by reversed phase high performance liquid chromotagraphy revealed the "inhibitory" activity to co-elute with TdR. Moreover, NCS did not suppress protein synthesis by chicken T cells growing with IL 2 and did not affect oxidative metabolism, cell viability, expression of IL 2 receptors, or percentages of cells in the S phase of the cell cycle. In accordance with these data, OS-sera suprisingly contain less TdR than those from normal controls. Experiments involving crosses of the OS with the normal inbred CB strain, revealed that the subnormal serum TdR level of the OS is an autosomally dominant trait which, however, segregates from T cell hyperreactivity. These findings falsify our previous hypothesis that a defect in specific IL 2 antagonists might be involved in T cell hyperfunction of the OS and indicate that NCS is devoid of factors which neutralize IL 2 function.

Lipid requirements of human T lymphocytes stimulated with mitogen in serum-free medium. Membrane "fluidity" changes are an artefact of lipid (AL721) uptake by monocytes

A correlation has been sought between the effects of lipids on membrane fluidity and mitogen responsiveness of human peripheral blood lymphocytes (PBL). Cholesterol and the reputedly potent membrane fluidizing agent AL721 (1) were used for these studies. However, the large AL721 induced increase in membrane "fluidity", assessed by steady state polarization of the probe 1,6-diphenyl-1,3,5-hexatriene (DPH), was found to be an artefact arising from lipid uptake by monocytes. Mitogen responses were enhanced by AL721 but unaffected by cholesterol. It is concluded that AL721 does not exert its effect through enhanced triggering of cells by altered membrane fluidity but rather that lymphocytes require an exogenous source of phospholipids/triglycerides for optimal growth in vitro, although they can synthesize sufficient cholesterol to meet their own needs.

The role of testosterone in spontaneous autoimmune thyroiditis of Obese strain (OS) chickens

We have recently reported a two-fold defect in glucocorticoid mediated immunoregulation in the Obese strain (OS) of chickens with spontaneous autoimmune thyroiditis (SAT): (i) a decreased basal corticosterone (CN) tonus due to an elevation of plasma corticosteroid-binding globulin (CBG) and (ii) an impaired CN rise in response to antigenic stimuli as well as lymphokines produced after mitogenic stimulation. The aim of the present study was to investigate the pathophysiological relevance of testosterone for the development of SAT. Compared to healthy normal White Leghorn chickens (NWL) the basal sex hormone tonus as well as androgen receptors of bursal tissue are not altered in the OS. Administration of sheep red blood cells (SRBC) or lymphokine containing conditioned media not only increased CN plasma levels but concomitantly modulated testosterone serum concentrations, although in an inverse direction and without significant difference between OS and healthy control chickens. These results suggest that, in contrast to the glucocorticoid system, androgen tonus as well as its modulation by immune signals are normal in the OS. The mode of action by which androgens exert their known beneficial effect on the development of SAT was also studied. According to our findings the capacity of testosterone to prevent SAT when administered during the posthatching period can be attributed to direct effects on bursal epithelial cells as well as indirect mechanisms, namely a fall in CBG levels leading to normalization of the CN tonus.

Failure to alter neonatal transplantation tolerance by the injection of interleukin 2

It has been postulated that the establishment of acquired, neonatal immunologic tolerance is due to a "deficit" in interleukin 2 (IL-2). To test this hypothesis, chickens were made immunologically tolerant to both major and minor histocompatibility antigens by transplantation of skin grafts onto newly hatched recipients. In this study, we injected various doses of IL-2 and concanavalin A simultaneously with transplantation and in some cases, several days posttransplantation, and we failed to enhance graft rejection. These results may have practical importance in respect to the clinical use of recombinant IL-2. Injection of IL-2 in and around surviving skin grafts also failed to alter skin graft survival.

Probing the receptor-interaction of glycoprotein hormones with monoclonal antibodies

Having recently analyzed with monoclonal antibodies (MCA) the immunologic surface of human chorionic gonadotropin (hCG) as consisting of 9 distinct epitopes exposed on the molecule in a characteristic topographical manner (Schwarz, S., Berger, P., and Wick, G., Endocrinology 118, 189-197, 1986) we now attempted to confirm this result on a more general basis, e.g. by incorporating MCA that were just recently obtained and previously not included. What we were, however, interested most was the question whether the tentative model of the epitope map of hCG could represent a "target" with which hCG-related hormones such as LH, FSH, and TSH (the family of glycoprotein hormones, GPH) would (partially) match. Indeed, repeating various immunizations with GPH of human as well as animal origin revealed a remarkable reproducibility in terms of several anticipated epitope specificities of MCA. This indicates that MCA can be regarded as reliable probes for mapping epitopes and, as we have presumed, of receptor interaction domains of GPH as well. Extending the originally used 2-site MCA binding exclusion approach by an interspecies crossreactivity (Xr) analysis we now are able to refine our epitope model of hCG such that 2 additional epitopes were found which were not previously resolvable. Most surprisingly, two of 5 epitopes on the alpha subunit were now also detected on various non-human GPH, which is in striking contrast to a seemingly well established dogma. Yet all five alpha epitopes of hCG are present on hLH, hFSH, and hTSH as well and arranged in the same spatial relationship to each other as on hCG. Even the 2 conformational epitopes and their close topographical relationship to the alpha-epitopes appear to be remarkably conserved on all human GPH. Among the beta-epitopes we have found one that is not shared by hLH and that - surprisingly - is not the C-terminal peptide (CTP) by which hLH differs from hCG. On the basis of this refined epitope map a way was paved along which it should be feasible to elucidate the sterical relationship of the epitopes to the receptor interaction domain(s) of hCG. To this end the MCA were tested in principally two ways: first, as to which of the 11 MCA with different epitope specificities would be able (or not) to inhibit by preincubation the binding of radiolabeled hCG (or hLH, respectively) to rat testis LH/hCG receptors? Secondly (and inversely) which of the 11 epitopes of hCG would still be accessible to binding by radiolabeled MCA when the (unlabeled) hormone is bound to the receptor?(ABSTRACT TRUNCATED AT 400 WORDS)

Diminished glucocorticoid tonus in obese strain (OS) chickens with spontaneous autoimmune thyroiditis: increased plasma levels of a physicochemically unaltered corticosteroid-binding globulin but normal total corticosterone plasma concentration and normal glucocorticoid receptor contents in lymphoid tissues

Obese strain (OS) chickens afflicted with spontaneous autoimmune thyroiditis (SAT) display several signs of a general immune dysbalance, some of which may be related to altered endocrine mechanisms such as the glucocorticoid tonus. The latter is the combined result of corticosterone (CN) production, metabolism as well as excretion, and the binding of CN to corticosteroid binding globulin (CBG) and glucocorticoid receptors (GR). The present study deals with the comparative investigation of these parameters in OS and normal White Leghorn (NWL) chickens. The results obtained with radioimmunoassay for CN and radioligand saturation assays for plasma CBG as well as GR in the thymus were as follows: (1) both OS and NWL have equal total CN levels; (2) however, OS chickens exhibit elevated CBG levels, whereas the physicochemical parameters (equilibrium affinity, specificity spectrum) of CBG were equal in OS and NWL; (3) the GR capacities and affinities were equal in both OS and NWL throughout development until thymic involution. Similarly, the specificity, affinity, and sedimentation behaviour were equal in OS and NWL. (4) Furthermore, no differences were found in the response of OS and NWL splenocytes to the suppressive effect of glucocorticoids in vitro, also excluding postreceptor alterations at the cellular level in the OS. From these findings we conclude that the increased CBG levels, which are not compensated for by either increased CN plasma levels or by increased receptor capacities or affinities in lymphatic organs, represent a diminished glucocorticoid tonus in OS chickens. This may have immunoregulatory consequences which, in turn, may contribute to the development of SAT.