CONTENTS
Review
- Mechanisms of Mouse T Lymphocyte-Induced Suppression of the IgG2ab Allotype and T Lymphocyte Tolerance to IgG2ab.
Lalech Majlessi and Guy BordenaveAbstract. In mice of the Ighaimmunoglobulin allotypic haplotype we found, the presence of T lymphocytes with an inherent inhibitory activity against the expression of the IgG2ab allotype (IgG2a of the Ighb immunoglobulin allotypic haplotype). This constitutive anti-IgG2ab T lymphocyte activity can be enhanced in vivo by what we called „sensitization”, which usually consists of one or two intravenous injections of B splenocytes from Ighb congenic mice. When injected at birth, the resulting anti-IgG2ab T splenocytes induce, with 100% success, total, specific and chronic (but experimentally reversible) suppression of IgG2ab in Igha/b F1 hybrid mice prepared by mating Igh congenic mice. Even if restricted to IgG2ab expression, this experimental model, which deals with an unambiguous case of T cell-mediated down-regulation of immu oglobulin production, provides a clear and powerful tool to dissect finely the behavior of the partners(T and B lymphocytes) intervening in regulation within the immune system. For example, we observed that CD4 T lymphocytes were necessary to obtain full recruitment of anti-IgG2ab CD8 T lymphocytes during the sensitization, that suppression induction in anti-IgG2ab T splenocytes of newborn recipients required cooperation between CD4 and CD8 T lymphocytes, and that CD8 T lymphocytes were essential for suppression maintenance. We showed that this suppression was not characterized by an accumulation of B lymphocytes containing the allotype they could not secrete or Cg2ab mRNA they could not translate. The recipient’s immune system was not involved in the suppession maintenance; this was done by donor T lymphocytes, which ensured the chronicity of IgG2ab suppression throughout the recipient’s life. We demonstrated that the mechanism of this suppression implied an MHC-restricted presentation by target B lymphocytes of Cg2ab peptides to the T cell receptor (TCR) of anti-IgG2ab T lymphocytes. Notwithstanding the requirement of a CD4-CD8 T lymphocyte cooperation during the induction phase, we functionally determined that the suppression induction implicated an MHC class I-, but not class II-restricted interaction. We also demonstrated the existence in vivo of alternative or concomitant use of perforine- and Fas-mediated cytotoxicity pathways in this T cell-induced IgG2ab suppression. Thus this suppression did not imply silencing IgG2ab production, but B lymphocyte destruction by CD8 T lymphocytes. Always using our suppression model, we demonstrated that an agonistic anti-CD40 treatment helps in recruiting CD8 cytotoxic T lymphocytes, involved in immune regulatory functions and that CD40 expression on Ighb B lymphocytes confronted with CD8 T lymphocyte effectors only operating via the Fas pathway was involved in the total suppression of IgG2ab expression. The selection and maintenance of such normal T cell activity against the IgG2ab allotype in mice of different genetic backgrounds remain somewhat enigmatic. Indeed, we did not observe any similar activity against other immunoglobulin allotypes or isotypes. The intestinal flora had no influence on the emergence of this anti-IgG2ab T lymphocyte activity, as it was untouched in germ-free Igha mice when compared with normal Igha mice. More recently, this model offered an opportunity to study problems pertaining to immune tolerance. For instance, we showed that the genetic elements involved in the building of anti-IgG2ab TCR were available in Igha and Ighb mice of different genetic backgrounds, but that somatic constraints, namely the perinatal presence of IgG2ab, effectively prevented their acquisition, while its absence led to their spontaneous emergence. Consequently, we were able to induce anti-IgG2ab T lymphocytes into a tolerance state by injecting Igha mice with soluble IgG2ab during the perinatal period. However, the full T lymphocyte tolerance obtained in this manner was not definitively acquired, as it had reversed spontaneously when investigated 3 to 6 months after the end of tolerogen treatment, even when this treatment had been prolonged from the perinatal period to 9 months of age. The mechanisms (induction and reversion) of this tolerance involves the physical elimination or the irreversible inactivation of the natural anti-IgG2ab T lymphocyte clones and their resurgence, from bone-marrow precursors, as long as the thymus remains operational, but not the establishment of a reversible, functional unresponsiveness (anergy) or an active, cell-mediated inhibition of anti-IgG2ab T clones. We attempted to elucidate, in Ighb mice, whether the natural T lymphocyte unresponsiveness to IgG2ab involved a central tolerance mechanism and to identify the type of tolerogen implicated in this tolerogenesis. The experiments principally showed that this natural T lymphocyte tolerance to IgG2ab was mediated by a thymic mechanism; that the capacity to induce it was gradually acquired by Ighb thymuses and was most probably due to potentially IgG2ab-producing/presenting cells, progressively colonizing the developing thymus; and that a significantly decreased postnatal Cg2ab gene transcription correlated with the emergence of anti-IgG2ab T lymphocytes in Igha/b F1 (postnatally deprived of their B lymphocyte compartment), which subjected them to autoimmune IgG2ab-allotype suppression.
Keywords: T lymphocytes; IgG2aballotype; suppression; tolerance; cytotoxicity; down-regulation of Ig production.
- Interleukin 10 and Its Role in the Regulation of the Cell-Mediated Immune Response in Syphilis
Marzanna Łusiak and Jadwiga PodwińskaAbstract. Data concerning interleukin 10 (IL-10), a cytokine of Th2 lymphocytes, and its inhibition of Th1 lymphocytes from secreting interleukin 2 (IL-2) and interferon (IFN) are presented. It has been indicated that IL-10 also inhibits other cells from producing interleukin 12 (IL-12) and nitric oxide (NO). It is known that all these factors take part in the cell-mediated immune response and immunity. This inhibition may facilitate the multiplication of Treponema pallidum and the development of disease despite the presence of immunologically competent cells. It has also been demonstrated that in late latent syphilis, when Th1 lymphocytes are not able to produce IL-2 and IFN, the cells are able to produce only IL-12 and NO. This fact seems to suggest that these factors take over the immune function when cells are stimulated again by treponemes which, after many years of latency, begin to multiply. Thus, a high level of IL-12 and NO seems to be an indicator of the development of the third stage of disease.
Keywords: IL-2; IFN; IL-10; IL-12; nitric oxide; cell-mediated immune response; syphilis.
Clinical Immunology
- Serum Autoantibodies Profile and Increased Levels of Circulating Intercellular Adhesion Molecule-1: a Reflection of the Immunologically Mediated Systemic Vasculopathy in Rheumatic Diseases?
Anna Kuryliszyn-Moskal, Piotr Adrian Klimiuk and Stanisław Sierakowski (Department of Rheumatology and Internal Diseases, Medical University of Bialystok, M. Skłodowskiej-Curie 24a, 15-276 Białystok, Poland)Abstract. Clinical manifestation of systemic vasculitis may be postulated as a consequence of the immune response abnormalities in the course of connective tissue diseases (CTD). The aim of this study was to elucidate the significance of the different autoantibodies and soluble intercellular adhesion molecule 1 (sICAM-1) shedding into the circulation in the diagnosis of vasculitis in rheumatic diseases. Serum of 86 patients with rheumatic diseases (54 with rheumatoid arthritis (RA) and 32 with CTD) were analyzed for the concentrations of sICAM-1 levels by the enzyme linked immunosorbent assay (ELISA). Control sera were obtained from 30 healthy individuals. Anti-nuclear antibodies (ANA), anti-double-stranded antibodies (anti-dsDNA) and anti-proteinase-3 (PR-3) antibodies (anti-neutrophil cytoplasmic autoantibodies cytoplasmic specific, cANCA) were assessed by the ELISA method. Fifty out of 86 patients had the systemic lesions. Pathological picture of the vascular loop in the nailfold capillary microscopy was found in 84 patients. In 19 patients the microvascular changes were advanced, in 35 moderate and in 30 mild. All patients with the articular manifestations had the pathological changes in the capillary microscopy. Patients with advanced changes in the capillary microscopy had the longer disease duration compared to patients with mild intensity of vasculitis. Serum concentration of sICAM-1 was significantly increased in RA and CTD patients compared to 30 controls (in both cases p<0.001). Moreover, RA and CTD patients with the systemic vasculitis showed significantly higher levels of sICAM-1 than those without vascular involvement (respectively p<0.001 and p<0.005). ANA were observed in significantly elevated concentration among RA and CTD patients with the systemic damage compare to patients without organ injury (respectively p<0.001 and p<0.05). Also cANCA level was twice more higher but only among CTD patients with the systemic damage (p<0.05). Serum concentration of sICAM-1 was elevated in studied patients with the presence of ANA antibodies (p<0.05). Significant correlation between ANA level and the disease duration, and hemoglobin concentration were observed. The concentration of cANCA correlated with rheumatoid factor and of dsDNA with patient age. We conclude that the systemic lesions in the course of RA and CTD are accompanied by the microvascular injury in nailfold capillary microscopy. Our data suggest that sICAM-1, ANA and cANCA serum levels may reflect the extent of the vascular involvement in RA and CTD patients.
Keywords: autoantibodies, sICAM-1, rheumatoid arthritis, connective tissue diseases, vasculitis, capillary microscopy.
- Lactoferrin Stimulates Killing and Clearance of Bacteria but Does Not Prevent Mortality of Diabetic Mice.
Tadeusz Zagulski, Zofia Jarząbek, Alina Zagulska, Magda Jaszczak, Iwona E. Kochanowska and Michał ZimeckiAbstract. We have previously shown that bovine lactoferrin (BLF) given intravenously (i.v.) protected mice against a lethal dose of E. coli and strongly stimulated both the clearing and killing activities in liver, lungs, spleen and kidney. Since some studies indicated a reduction of the manifestation of experimental pancreatitis with lactoferrin, we decided to examine the protective activity of BLF against lethal E. coli infection in animals with alloxan (Alx)-induced diabetes. It appeared that 48 h diabetes substantially lowered the killing activity in all four organs as well as the clearing rate of E. coli from the circulation. BLF given i.v. o reduced this undesirable effect of diabetes. However, in 10- and 20-day diabetic animals, the diabetes alone stimulated the killing activity in the organs investigated, and upregulated the clearing rate of E. coli from the circulation. Lactoferrin (LF) significantly increased both the killing and the clearing activity in these long-term diabetic animals. In some cases the stimulating effect of BLF was very high, suggesting a concerted action of BLF and diabetes in that category of mice. Despite these beneficial effects of BLF and diabetes on the killing process in the investigated organs, the survival time of animals from all the diabetic groups ( 48 h, 10 and 20 days) was not prolonged by BLF. The protective properties of BLF did not depend on the blood glucose levels in the diabetic animals. BLF partly delayed the development of experimental Alx-induced diabetes, measured by the glucose level, but only if administered shortly after Alx injection. In conclusion, we demonstrated that the state of diabetes alone could increase killing of bacteria in the investigated organs and LF enhanced this process. However, LF had no protective effect against the mortality of diabetic mice infected with a lethal dose of E. coli.
Keywords: lactoferrin; protective activity; lethal infection; diabetes; E. coli; mice.
- Investigation of Serum Cytokine Levels and Cytokine Production in Whole Blood Cultures of Paranoid Schizophrenic Patients.
Teresa Kamińska, Alicja Wysocka, Halina Marmurowska-Michałowska, Halina Dubas-Ślemp and Martyna Kandefer-SzerszeńAbstract. There is some evidence that the pathophysiology of schizophrenia is related to changes in the innate and adaptive immune systems. In an attempt to define a potential immunological dysfunction in schizophrenia, we measured the serum levels of several cytokines in the sera of 24 patients with paranoid schizophrenia and investigated the cytokine production in whole blood assays after stimulation in vitro with virus (Newcastle disease), phytohemagglutinin (PHA) or bacterial lipopolysaccharide (LPS) and compared them with healthy, normal controls. A significant increase of IL-6, IL-8 and IFN-g levels, but a decreased IL-10 level were observed in the sera of patients with schizophrenia. No significant changes in the serum levels of IL-2, IL-4, IFN-a and TNF-a were detected in these patients. When cytokine production in vitro was examined, a significant defect in PHA-induced IL-2, IL-4 and IFN-a, and in virus-induced IFN-a production, but no significant alterations in LPS-induced IL-6, IL-10 and TNF-a production were observed. In summary, increased serum levels of some cytokines such as IL-6, IL-8 and IFN-g indicate an activation of the inflammatory response in schizophrenia, while the in vitro assay indicates significant changes in the Th1 (decreased production of IL-2 and IFN-g) and Th2 (decreased production of IL-4) cell system responses. The role of the defective IFN-a production in the regulation of the imbalance between Th1 and Th2 cell system responses is suggested.
Keywords: paranoid schizophrenia; cytokine production; IL-2; IL-4; IL-6; IL-8; IL-10; IFN-a; IFN-a; TNF-a.
Cellular Immunology
- Influence of Dendritic Cells on the in Vitro Allogeneic Cytotoxic Reaction of Lymphoid Cells Derived from Normal or Listeria innocua-Infected BALB/c Mice
Teresa Gościcka, Maria Walencka, Marek Fol, Agnieszka Krupa and Jacek SzeligaAbstract. The role of lymphoid dendritic cells (DCs) in the development of an allogeneic cytotoxic reaction in vitro was examined. The T+B and T cell subsets originating from the spleens or lymph nodes of normal and Listeria innocua-infected BALB/c mice were used as the effector cells. Their cytotoxicity to 51Cr-labeled C3H fibroblasts was determined after removal of DCs and replacing them again. Moreover, the influence of exogenous mrIL-12 on the potency of DCs in the allogeneic reaction developed in vitro was checked. It was found that the DC-deprived T+B or T subsets of splenocytes, regardless of their origin, exhibited 27-38% lower cytotoxicity than those accompanied by natural DCs. The cytotoxicity of these subsets from normal lymph nodes decreased by 22%, while the activity of bacteria-primed cells dropped by 38%. Replenishing effector cells with isolated DCs restored their cytotoxicity. Pulsation of normal DCs with IL-12 had no effect on the recovery of normal cell cytotoxicity. However, the IL-12-pulsed DCs were able to intensify the cytotoxicity of T+B subsets derived from the spleens or lymph nodes of L. innocua-infected mice. The results suggest that the alloantigen presentation by DCs to cytotoxic lymphocytes also takes place in the reaction developed in vitro, regardless of effector cell origin.
Keywords: dendritic cells; cytotoxicity; allogeneic reaction; Listeria innocua.
- Effect of IFN-g on Expression of HLA in Bare-Lymphocyte Syndrome-Like Cell Line HAJ
Izabela Nowak, Bogusława Pochroń, Anita Kozłowska, Joanna Dubis and Piotr Kuśnierczyk
Abstract. We compared HLA antigen expression on new B-lymphoblastoid cell line (B-LCL) HAJ with that on B-LCLs expressing normal HLA levels as well as on B-LCLs derived from bare lymphocyte syndrome (BLS) patients and in vitro mutated B-LCLs of BLS-like phenotype. HAJ cells had no expression of HLA class II and low expression of class I antigens similarly to some of BLS B-LCLs, although HAJ cell line was derived from lymphocytes of HLA class I- and class II-normally expressing donor. HAJ cells displayed B lymphocyte markers, surface immunoglobulin and CD19. Culture of HAJ cells in the presence of interferon gamma resulted in HLA class I antigen upregulation, but did not restore class II expression. The cell line HAJ may prove useful for studies on factors influencing HLA class I cell surface expression.
Keywords: HLA expression defect, B-lymphoblastoid cell line, flow cytometry, interferon g.