La Antigen Expression Research Articles

Interferon-gamma stimulates the secretion of IL-1, but not of IL-6, by glomerular mesangial cells.

IL-1 activity in culture supernatant and cell lysate from rat mesangial cells stimulated with interferon-gamma (IFN-gamma) was measured by a thymocyte proliferation assay. While IFN-gamma alone had no effect on the secretion or the intracellular pool of IL-1, the enhancement by IFN-gamma of IL-1 secretion in response to lipopolysaccharide (LPS) was observed. The stimulatory effect of culture supernatant on thymocyte proliferation was abrogated by preincubation with the anti-IL-1 antibody. At least 4-h incubation with IFN-gamma and LPS was required to detect enhancing effect of IFN-gamma. The addition of as little as 1 U/ml IFN-gamma significantly increased IL-1 secretion in the presence of 10 micrograms/ml LPS. The IL-6 activity in culture supernatants was determined by measurement of thymidine uptake in mouse IL-6-dependent cell line (MH60.BSF2). Mesangial cells secreted IL-6 in culture supernatant without additional stimuli and LPS distinctly increased it as described previously. However, in contrast to IL-1 production, no effect of IFN-gamma on IL-6 secretion was observed in the presence or absence of LPS. Moreover, we determined whether enhanced IL-1 release is associated with Ia expression on mesangial cells. IFN-gamma alone and the combination with LPS induced marked expression of Ia antigen, whereas LPS alone did not. We conclude that IFN-gamma stimulates the production of IL-1, but not IL-6, by mesangial cells and suggest an important role of IFN-gamma in the pathogenesis of glomerulonephritis by regulating the mesangial production of IL-1 and the accessory cell function of mesangial cells.

Heterogeneity in the expression of Ro and La antigens in human skin.

To determine whether there are variations in the expression of Ro and La antigens in human skin. Levels of expression of Ro and/or La antigens in 26 specimens of normal human skin (11 sun-exposed, 15 sun-protected) were measured by indirect immunofluorescence with monospecific antisera. Levels of expression of both antigens varied by more than 2,000-fold in the skin of different individuals. There usually was a correlation between the levels of expression of Ro and La antigens in the same skin specimen. There was no correlation found between the levels of Ro or La antigen expression and sun exposure, nor was there a correlation found between levels of antigen expression and location of the skin on the body. There is a marked heterogeneity in the expression of both Ro and La antigens in the skin of different individuals. The present study findings suggest that the levels of expression of these antigens may play a role in the propensity of some individuals to develop anti-Ro or anti-La antibodies and/or skin lesions associated with the presence of these antibodies.

Interferon-gamma and epithelial cell activation in Sjögren's syndrome.

We have examined the hypothesis that interferon-gamma (IFN-gamma) and its interaction with epithelium may play a role in the perpetuation of inflammation in Sjögren's syndrome (SS). Labial salivary gland primary cell cultures from 16 patients with primary SS (pSS) and eight cultures from patients with SS symptoms but histologically normal biopsies were examined for expression of HLA-DR and cytoplasmic La (SS-B). Epithelial HLA-DR expression was found in 80% of cultures from pSS patients and 38% of those from patients not fulfilling diagnostic criteria. Cytoplasmic La was detected in 50 and 38% of cultures, respectively. Treatment of 14 of the cultures with IFN-gamma increased HLA-SR and cytoplasmic La expression above that of untreated cultures. Depletion of IFN-gamma using neutralizing antibody had the reverse effect. These findings suggest that the perpetuation of chronic inflammation of pSS may be due to the induction of HLA-DR and La antigen expression on epithelial cells by IFN-gamma.

Enhancement of Ia antigen expression and nonproliferating cells correlates with metastatic capacity.

Maintaining B16F10 tumor cells in stirring culture for 48 h leads to an increase in lung and liver colonizing capacity in comparison with cells in adherent culture. Parallel to the increased metastatic capacity, we have observed a decrease in the proliferative rate of tumor cells (as the percentage of proliferating cell nuclear antigen-positive cells) and an increase in the population of tumor cells expressing Ia antigen. These results are not exclusive to B16F10 cells, since the same results were obtained when we analyzed 3LL cells maintained in identical culture conditions. In all the tumor lines tested, we found an association between the nonproliferating and the Ia-positive cell populations. We induced Ia expression by treating B16F10 cells in adherent culture with the lectin concanavalin A and again, coincident with an increase in metastatic capacity, we found the same association between the two parameters analyzed--nonproliferating state and Ia antigen expression. In addition, it was found that B16F10 cells induce lymphocytic proliferation, and a direct relationship was established between the number of Ia+ cells and lymphocytic proliferation.

Pancreatic β-cell destruction in non-obese diabetic mice

We determined the natural history of the widespread pancreatic islet β-cell destruction that precedes the onset of spontaneous putative autoimmune diabetes mellitus in NOD mice. For this purpose, we performed both histological and immunocytochemical examinations of pancreata retrieved from mice at 2 through 30 weeks of age. An overexpression of la antigens was identified on islet β cells at 4 weeks of age, without evidence of mononuclear cell infiltration. The abnormal expression of la antigens was age-related and was associated with hyperexpression of class I antigens and progressive islet cell histologic damage after 17 weeks of age. Immunocytochemical examination of islet cell infiltrate showed that the number of macrophages did not increase during the early phase of islet cell damage in these mice. The L3T4 Lyt-2 ratio increased after 7 weeks of age, but was 1:1 in the late stage of insulitis. These findings suggest that widespread islet β-cell destruction is a process that begins primarily with derangements of the pancreatic β-cell immune pattern, which may trigger a mononuclear cell reaction.

The expression of MHC class II (Ia) antigens on mouse keratinocytes following epicutaneous application of contact sensitizers and irritants

The expression of MHC class II (Ia) antigens on mouse keratinocytes was studied following both the induction and elicitation of contact sensitivity, and after primary irritant reactions. IA+ and IE+ keratinocytes were detected, using an indirect immunofluorescence assay on epidermal sheets, only after the induction and elicitation of contact sensitivity with the sensitizers oxazalone, picryl chloride and 2,4-dinitrochlorobenzene but not with formaldehyde. Ia+ keratinocytes were not detected after epicutaneous application of the non-sensitizing irritants croton oil, SDS and anthralin, or following attempted sensitization of nude mice, suggesting that the expression of Ia antigen on keratinocytes during contact sensitivity reactions is T-cell mediated. Because Ia antigen expression on keratinocytes could be detected only several days after induction or elicitation of contact sensitivity, and contact sensitization could also be demonstrated to occur independently of aberrant Ia expression, Ia+ keratinocytes cannot be involved in the initiation of these reactions. However, they might be important in exerting an immunomodulatory influence during the later stages of the responses to certain sensitizers.

Granules of human CD3+ large granular lymphocytes contain a macrophage regulating factor(s) that induces macrophage H 20 2 production and tumoricidal activity but decreases cell surface la antigen expression

CTL (cytotoxic T lymphocytes) and LGL (large granular lymphocytes) exocytose cytoplasmic granules on activation after recognition of their target, releasing granule-associated molecules. We have previously suggested that this process could release immunoregulatory molecules. In this study we investigated whether normal human LGL. granules contained a factor regulating different macrophage activity. Human CD3+ LGL cells were generated by activating peripheral blood lymphocytes (PBL) for 10–12 days with recombinant human IL-2 (rhIL2), and granules were isolated from disrupted cell homogenate by Percoll gradient fractionation. Solubilized granules were tested for macrophage-activating factor (MAF) activity in three different macrophage assays. When M-CSF-differentiated murine bone marrow-derived macrophages were incubated 9 hr with human LGL granules, they were fully activated to lyse the TNF-resistant P815 tumor cells. The granule-MAF showed a synergistic effect with rhIL-1β, rmTNF-α, and rmlFN-τ in the cytolytic assay. In addition, proteose-peptone-elicited murine peritoneal macrophages profoundly increased H 20 2 production after activation with human LGL granules. However, unlike IFN-τ, no increase in peritoneal macrophage la antigen expression was detected after incubation with granules. Moreover, granule-MAF suppressed la induction by IFN-τ. These results confirm that human CD3+ LGL granules contain a molecule(s) capable of regulating macrophage function.

Microbicidal Activities of <i>Salmonella typhimuriu</i><i>m</i>- and Interferon-Gamma-Activated Mouse Peritoneal Macrophages

Activation of mouse peritoneal macrophages during infection of mice by various facultative intracellular bacteria and after intravenous injection of recombinant interferon-gamma (rIFN-gamma) was studied. Macrophage activation was demonstrated on the basis of three different criteria, i.e. inhibition of Toxoplasma gondii proliferation, enhanced release of H2O2 and increased expression of Ia antigen. Macrophages activated during an infection with Salmonella typhimurium showed no enhanced salmonellacidal or listericidal activity relative to control macrophages, whereas Listeria-activated macrophages killed Listeria but not Salmonella faster than control macrophages. The rate of proliferation of Salmonella in spleen and liver of activated mice was comparable to the proliferation in the organs of control mice. rIFN-gamma-activated macrophages displayed neither an enhanced salmonellacidal nor an enhanced listericidal activity. When high numbers of Listeria were injected intravenously the proliferation in spleen and liver of rIFN-gamma-treated and control mice was similar. The proliferation of Listeria in the liver of rIFN-gamma-treated mice was less than in control mice when 1 LD50 or lower numbers of bacteria were injected. It is concluded that peritoneal macrophages become activated during infections of mice with various intracellular pathogens. However, these activated macrophages do not show enhanced bactericidal activity against all bacteria. Furthermore, rIFN-gamma is not sufficient to enhance the listericidal activity of macrophages.

Internalization of gold-labeled IA antigens induces formation of Birbeck granule-like structures in murine Langerhans cells

Langerhans cells (LC) are migratory bone marrow-derived dendritic cells that reside in the basal portion of the epidermis. LC are antigen presenting cells; they express MHC Class II antigens, macrophage maturation marker, F4/80, and exhibit a distinctive cytoplasmic pentalaminar organelle called Birbeck granules (BG). Murine LC have fewer BG than human LC. The origin of BG is not clear although several reports suggest that BG are formed by invagination of the cytomembrane to form a membrane sandwich.In this study, dendritic cells (DC) from the draining lymph nodes (DLN) of mice previously sensitized with fluorescein isothiocyanate were examined by fluorescence and electron microscopy. Expression of la antigen by dendritic cells was determined by immunogold labeling using either Janssen Auroprobe GAM40 (Amersham Corporation, IL) as the secondary antibody or Protein- A-gold (20nm) (Polysciences, Inc., PA) label. Cells were labeled at 4°C and then warmed to ambient temperature. Samples were taken a t various time intervals and processed for TEM. Serial sections of dendritic cells were examined for presence of BG.

La Antigen Expression by Reticulum Cells in Lymphoid Tissues and Mesenchymal Cells in the Interstitium of the Heart and Liver of Adult Rats

In an earlier series of studies on cellular labeling with [14C]adenine ([14C]A) in adult rats. Osogoe and his colleagues demonstrated the occurrence of certain cell types which are capable of incorporating [14C]A to a particularly great extent, such as the immature forms of either macrophage or fibroblast or reticulum cell lines. Further investigations have revealed that, among such cell types, a few fibroblastoid cells in the interstitium of the kidney and lung, as well as the proliferative reticulum cells in the intestinal lamina propria, express Ia antigen. In the present study, the reticulum cells in the lymphoid tissues and an appreciable number of mesenchymal cells in the interstitium of the heart and liver were also found to express Ia antigen. These two types of Ia-positive cells were characterized by a large cell body having a large euchromatic nucleus and abundant cytoplasm with dendritic processes. However, the mesenchymal cells were found in the interstitial tissue space of the organs, mostly scattered singly or occasionally grouped in small cell aggregations, without coexisting lymphoid cells. The biological significance of the Ia antigen expression by the two cell types, in particular the mesenchymal cells, is discussed in relation to their capacity for uptake of [14C]A.

Erythema dyschromicum perstans: Immunopathologic studies

Immunopathologic studies of a patient with clinical and histologic evidence of erythema dyschromicum perstans revealed la antigen expression on epidermal keratinocytes, pronounced OKT4 and OKT6 staining of epidermal dendritic cells, and dermal infiltration of T lymphocytes of both helper-inducer (OKT4) and suppressor-cytotoxic (OKT8) phenotypes—a pattern commonly associated with lichen planus. These findings, taken in conjunction with positive IgG staining on colloid bodies, suggest the possibility that erythema dyschromicum perstans and lichen planus have similar disease processes.

Dimethylnitrosamine-induced cirrhosis: Evidence for an immunological mechanism

The present study is concerned with the early events associated with the development of cirrhosis induced by dimethylnitrosamine (DMN). The antigenic expression of MHC class II components (Ia) and of some intermediate filament proteins (vimentin and desmin) have been studied by immunohistochemistry and the findings correlated with ultrastructural data. Micronodular cirrhosis developed after 3 weeks of treatment with DMN but enhanced expression of la antigen on macrophages and on infiltrating lymphocytes was observed after 1 week, before the formation of septa, suggesting that immune-mediated mechanisms are involved in the response to DMN-induced liver injury. The expression of vimentin and of desmin also increased at an early stage and at 3 weeks the septa were outlined by cellular elements showing positivity for both intermediate filament proteins. In keeping with these observations, ultrastructural data showed active division of macrophages in situ, infiltration of the parenchyma by T and B lymphocytes, activation of lipocytes (Ito cells) showing evidence of mitosis, and the presence of transitional elements between lipocytes, myofibroblasts and fibroblasts. This experimental model may be helpful in understanding the relationship between immune-mediated response to liver injury and development of hepatic fibrosis.

Effects of Rat γ- and Non-γ-Interferons on the Expression of la Antigen, Growth, and Differentiated Functions of FRTL5 Cells*

We undertook the present studies with several objectives in mind: 1) to determine whether recombinant rat gamma-interferon (r gamma IFN) would induce expression of the class II major histocompatibility antigen (Ia) in rat thyroid follicular cells (FRTL5) in culture as human gamma IFN does in cultured human thyrocytes; 2) to characterize the properties of this response, if it does indeed occur; 3) to ascertain whether r gamma IFN has any effect on the growth or differentiated function of FRTL5 cells; and 4) to determine how, if at all, effects of r gamma IFN on the growth and function of FRTL5 cells might be related to expression of the Ia antigen. At concentrations between 1 and 30 U/ml, r gamma IFN induced expression of Ia antigen in a concentration-dependent manner. With a supramaximal concentration of r gamma IFN, Ia antigen first appeared between 4 and 16 h and reached a maximum concentration at about 36 h. After removal of r gamma IFN, the Ia antigen concentration remained constant for about 24 h and then declined, becoming undetectable by 72 h. Induction could not be detected in FRTL5 cells cultured with human gamma IFN, rat non-gamma IFN, Concanavalin-A, phytohemagglutinin, or bovine TSH (bTSH). Over the same range of concentrations that induced the Ia antigen, r gamma IFN proved to be a potent inhibitor of the growth of FRTL5 cells induced by a variety of agents. It produced a concentration-dependent inhibition of the stimulation of [3H] thymidine incorporation and cell replication in FRTL5 cells induced by bTSH. This effect was unaccompanied by any inhibition of either the binding of bTSH to FRTL5 cells or the bTSH-induced increase in cellular cAMP concentration induced therein. However, r gamma IFN did inhibit the stimulation of [3H] thymidine incorporation into DNA induced by (Bu)2cAMP. r gamma IFN also inhibited the stimulation of DNA synthesis and cell replication induced by insulin-like growth factor I (IGF-I) without affecting the specific binding of IGF-I, and decreased the extent of stimulation of [3H]thymidine incorporation induced by the phorbol ester tetradecanoyl phorbol acetate (TPA). Thus, r gamma IFN inhibited both the cAMP-dependent pathway of growth activated by TSH, doing so at some post-cAMP locus, and the cAMP-independent pathways of growth regulation that are activated by IGF-I and TPA.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of bilirubin on murine peritoneal and spleen cells

The effect of bilirubin on murine peritoneal and spleen cells was investigated. Bilirubin was found to have a strong and rapid effect on the expression of various kinds of Fc receptors on peritoneal macrophages. Significant changes were observed 30 min after the infection of bilirubin. The return to normal values was not observed earlier than after 24 h. The effect of bilirubin on Fc receptor expression of splenic macrophages was less pronounced. Expression of Ia antigen on macrophages was not influenced by bilirubin. The changes in percentage of sIg+ and Thy 1.2+ lymphocytes reflect a change in the ratio of T to B cells in the peritoneal cavity, as bilirubin caused 40% increase in numbers of B cells and a similar decrease in numbers of T cells. The percentage of splenic B lymphocytes was not influenced by bilirubin injection; but the ratio of T helper to suppressor cells was altered.

Effect of Interferon-γ Treatment on the Course of a Burn Wound Infection

Interferon-gamma (IFN-gamma) has been shown to have immunoregulatory properties and is able to modulate resistance to several microbial infections. This study was designed to determine the efficacy of IFN-gamma treatment in a murine burn wound infection model. Bacterial challenge consisted of Klebsiella pneumoniae (10(8) organisms/ml) or Pseudomonas aeruginosa (10(8) organisms/ml), applied topically immediately after burning. Groups of CBA/J mice received either IFN-gamma or RPMI-1640 medium (controls) subcutaneously. IFN-gamma was administered daily at a dose of 7,500 units for 5 days prior to bacterial challenge. Burn without bacterial challenge produced no mortality. Mice treated with IFN-gamma survived significantly longer than controls when the bacterial challenge was K. pneumoniae. There was no difference in survival when bacterial challenge was P. aeruginosa. The Ia antigen expression of peripheral blood mononuclear cells was severely reduced for 3 days post-burn. This drop was prevented on day 3 post-burn in mice treated with IFN-gamma. These data indicate that interferon was effective treatment in a murine model of Klebsiella burn wound infection and was associated with maintenance of Ia antigen expression that may have contributed to the action of the IFN-gamma.

Possible role of T cells in the establishment of IgG plasma cell‐rich periodontal lesion –Augmentation of IgG synthesis in the polyclonal B cell activation response by autoreactive T cells

The effect of T cells on T‐independent polyclonal B cell activation (PBA) was studied in vitro in mice. Helper/inducer T cells were activated by interaction with la antigens expressed on B cells. The activated T cells enhanced IgG synthesis in the PBA reaction. la antigen expression on B cells increased when stimulated by polyclonal B cell activators. An autoreactive T cell line was established by longterm culture of spleen cells with polyclonal B cell activators. The culture supernatant from this autoreactive T cell line enhanced IgG synthesis in PBA. The above results suggest that autoreactive T cells were activated by la expressed on B cells stimulated with polyclonal B cell activators, and then prompted B cells to synthesize IgG. Therefore, autoreactive T cells may play an important role in the establishment of the IgG plasma cell‐rich periodontal lesion.

Ontogeny of macrophages and dendritic cells of the rat.

Earlier studies on the ontogeny of macrophages have demostrated that the immunological immaturity of newborn rodents is at least in part due to the immaturity of the macrophage system (1,2). In particular the capacity of macrophages to present antigen and thus induce an adequate immune respons was impaired in neonates as compared to adults (13,19,21), which appeared to be due to a low number of la-positive antigen presenting cells (15,20). A considerable number of studies are now available on the ontogenetic development of antigen presenting cells in the different lymphoid organs as thymus (10,12), gut and gut-associated tissue(17,25,26), spleen (7,11) and lymph node (24) or in cell suspensions of these organs (14,16). In these studies, the antigen presenting cells, in particular the interdigitating cells (IDC, in tissues) respectively dendritic cells (DC, in cell suspensions) were studied using either their expression of la-antigen or their antigen presenting capacity as characteristic.

Impaired cytokine response in male ICR Swiss mice after infection with D variant of encephalomyocarditis virus.

The basis for the resistance of the female and the susceptibility of the male ICR Swiss mouse to the diabetogenicity of the D variant of encephalomyocarditis virus (EMCV-D) is unknown. This pattern of disease resistance and susceptibility can be reversed if females are treated with testosterone and males are treated with estrogen before virus infection. As a possible explanation for this sex difference in disease development, differences in early antiviral host responses were explored. Cellular antiviral resistance mechanisms operative early in virus infection were evaluated in ICR Swiss mice of both sexes after intraperitoneal infection with virus. No differences were seen in splenic natural killer (NK) cell responses of male and female mice during the 1st wk of infection, during which only the males became diabetic. Depletion of NK cell activity with rabbit anti-asialo GM1 serum did not render the infected ICR Swiss female susceptible to virus-induced diabetes. Treatment of ICR Swiss mice with type I carrageenan to compromise macrophage function rendered the female susceptible to diabetes after infection with EMCV-D but made only the male susceptible to diabetes by the usually avirulent interferon-inducing EMCV-D. Concanavalin A and recombinant interleukin 2, inducers of immune interferon, which in turn primes macrophages for activation and induces their expression of la antigens, protected the ICR Swiss male against the diabetogenic effects of EMCV-D. Interleukin 2 enhanced the male's capacity to exhibit an increase in the expression of Ia antigen by peritoneal exudate cells 1 day after injection with EMCU-D to a level seen in disease-resistant females.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor-alpha induces increased hydrogen peroxide production and Fc receptor expression, but not increased Ia antigen expression by peritoneal macrophages.

It has recently been shown that tumor necrosis factor (TNF) induces increased Ia antigen expression on a malignant murine macrophage cell line, and that TNF is synergistic with gamma interferon (IFN) in inducing Ia expression. This finding raises the possibility that TNF serves as a non-interferon macrophage activating factor in vivo. Since it is known that TNF has different effects on malignant and benign cells, we chose to evaluate the effects of recombinant TNF on primary cultures of murine peritoneal macrophages (MP). Neither human nor murine TNF increased the proportion of MP which expressed Ia antigen, and TNF actually partially prevented the IFN-induced increase in Ia. However, culture with TNF activated MP for increased hydrogen peroxide production in response to phorbol myristate acetate (PMA) and antagonized the IFN-induced decrease in the proportion of the MP bearing receptors for the Fc region of IgG2b. TNF and IFN were additive in increasing peroxide production. Both human and murine TNF had the same effects on MP, and MP from C3H/HeN (endotoxin sensitive) and C3H/HeJ (endotoxin resistant) mice responded comparably to TNF and IFN. Our results support the hypothesis that TNF has some macrophage-activating activity, but its effects are selective and not identical with those of IFN.

Intestinal mucosal mast cells in rats with graft-versus-host reaction.

In clinical practice, small intestinal mucosal damage with villus atrophy and crypt hyperplasia (enteropathy), occurs in association with immune reactions to alloantigens, parasites and dietary proteins. A similar, distinct pattern of mucosal pathology has been recognized in delayed type hypersensitivity reactions in animals, including mice, rats, pigs and calves. Experimental models used include allograft rejection, graft-versus-host reaction (GvHR), enteral challenge after immunization with protein antigen or contact sensitizing agent, and parasite infections. The features described in some or all of these situations are hyperplasia of the crypts of Lieberkuhn with or without shortening of the villi; an increase in the proportion of goblet cells; brush border enzyme deficiency; increased count of intraepithelial lymphocytes (IEL); an increased mitotic index of IEL; and expression of la antigen on crypt enterocytes (1).