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Biomedical subjects

A Dujić

Publications and source records attributed to A Dujić.

At least 19 recordsLinked to original sources
PubMed1992

Interferon gamma alters the phenotype of rat thymic epithelial cells in culture and increases interleukin-6 production.

Rat thymic epithelial cells (TEC) in long-term culture were characterized by anticytokeratin monoclonal antibodies (mAbs) and electron microscopy. Phenotypic analysis performed by a large panel of mAbs showed that the highest percentage of these cells was of the subcapsular/medullary type. Recombinant rat interferon (IFN)-gamma up-regulated class-I and class-II MHC expression by TEC in culture as confirmed by immunohistochemistry and flow cytometry, but did not significantly alter other cell markers. TEC supernatants of IFN-gamma-treated cultures showed higher interleukin-6 (IL-6) activity, compared to the control, as determined by proliferation of the IL-6-sensitive B9-cell line. Increased IL-6 activity was probably not a consequence of increased TEC number in IFN-gamma-treated cultures because IFN did not significantly stimulate TEC proliferation in vitro. In contrast, IL-6 significantly stimulated TEC proliferation, indicating that this cytokine is not only a regulatory molecule for T-cell proliferation, but could also be an autocrine growth factor for thymic epithelium.

Animals↗
PubMed1992

Phenotypic and ultrastructural characterization of an epithelial cell line established from rat thymic cultures.

An epithelial cell line (TE-R 2.5) was established from a long-term culture of rat thymic epithelium. Its epithelial nature was confirmed using anti-cytokeratin (CK) monoclonal antibodies (mAb) and electron-microscopy. TE-R 2.5 cells were reactive with K 8.13, K 8.12, CK 8, R-MC 18, R-MC 19 and Mar 3 mAb and bind Ulex europaeus agglutinin I. Based on the results of this study it was concluded that they possess the phenotype of subcapsular/perivascular or medullary epithelium. This was in accordance with Western blot analysis of water-insoluble cell extracts showing the presence of 56,000, 52,000, 50,000 and 48,000 MW CK polypeptides. In addition, TE-R 2.5 cell line coexpressed CK and vimentin (a 57,000 MW polypeptide) which was demonstrated using dual immunohistochemistry and Western blot analysis. Electron microscopy demonstrated that TE-R 2.5 cells have all the characteristics of hypertrophic thymic epithelial cells (TEC) localized in situ exclusively in the medulla and thus further characterized this line as a type of medullary TEC. Finally, TE-4F10 mAb raised against an antigen of TE-R 2.5 cells selectively stained a subset of medullary TEC in situ including Hassall's corpuscles indicating again the medullary origin of this TEC line.

Animals↗
PubMed1991

Rat thymic epithelial cells in culture constitutively secrete IL-1 and IL-6.

To study the in vitro interactions between rat thymic non-lymphoid cells and thymocytes, we established a system for long-term cultivation of thymic epithelial cells (TEC). TEC were cultivated and successfully propagated for over 8 months in RPMI 1640 medium containing 15% FCS, dexamethasone, insulin, epidermal growth factor, and poly-L-lysin as an adhesive matrix. Their epithelial nature has been confirmed using monoclonal anti-cytokeratin (CK) antibodies. More than 95% of these cells were reactive with K 8.13 and CK 8 mAbs, which are pan-epithelial markers for rat TEC in situ. An epithelial cell clone (TE-R 2.5) established from a long-term TEC culture was 100% reactive with these anti-CK antibodies. Phenotypic analysis of TEC cultures was performed by a large panel of mAbs reactive with a subset of rat TEC or CK polypeptides as well as UIex europaeus agglutinin I using a streptavidin-biotin immunofluorescence assay. Although the results obtained demonstrated phenotypic heterogeneity among these cells, most cultures, including the TE-R 2.5 clone, were of subcapsular/medullary phenotype. Medium conditioned by TEC cultures exhibited IL-1 and IL-6 activities when tested on D10S and B9 sensitive cell lines, respectively. Cytokine activities were neutralized (IL-1) or significantly inhibited (IL-6) by specific polyclonal antibodies. In addition, both anti-IL-1 and anti-IL-6 antibodies reacted with TEC in culture and epithelial (CK-positive) cells on thymic cryostat sections, indicating that thymic epithelium provides an important intrathymic source for molecules contributing to T cell activation.

Animals↗
PubMed1991

Primary culture of rat thymic non-lymphoid cells: influence of culture time on the expression of macrophage differentiation antigens defined by monoclonal antibodies.

A panel monoclonal antibodies (mAbs) raised to rat thymic non-lymphoid cells has been shown to discriminate between distinct subpopulations of macrophages depending on their anatomic localization in the thymus. These reagents were used in this study to examine the expression of macrophage-associated antigens in primary culture of rat thymic stromal cells. The phenotype of both adherent macrophage (AM) monolayers and non-adherent cells (NAC) released in culture medium was studied at different time points after cultivation. More than 95% AM expressed ED1 and R-MC 38 antigens (pan-macrophage markers), class I MHC antigens (OX-18) and iC3b receptor recognized by OX-42 mAb. Most of them (70-85%) were reactive with ED2, R-MC 40, 41 and 42 mAbs specific for cortical and cortico-medullary zone (CMZ) macrophages. A much smaller percentage was positive with R-MC 43/44 and R-MC 46/47 mAbs staining CMZ/medullary macrophages and a subset of cortical macrophages, respectively. A minor subset of AM expressed class II MHC molecules which progressively decreased during cultivation. NAC were phenotypically heterogeneous. In comparison with adherent cells they contained a lower percentage of cortical/CMZ phenotype macrophages. In addition, NAC were slightly enriched in R-MC 43+ cells and more significantly expressed IA/E antigens (85-95%). ED3, R-MC 39 and 45 mAbs reactive with thymic macrophages in situ were mostly non-reactive with AM and NAC in culture.

Animals↗
PubMed1990

Interspecies differences in expression of cytokeratin polypeptides within thymic epithelium: a comparative immunohistochemical study.

Cytokeratin (CK) polypeptide expression within the thymic epithelium of several mammalian species (mouse, rat, calf, pig, rabbit, and human) has been analyzed by the streptavidin-biotin immunoperoxidase method. Comparative analysis by a large panel of 17 monoclonal antibodies (mAbs) specific for individual CK polypeptides, pairs, or groups showed considerable heterogeneity of thymic epithelial cells (TEC) in each species. In addition, extreme interspecies difference in CK contents was observed. Four main phenotypic zones: the subcapsule/perivascular area, cortex, medulla, and Hassall's corpuscles (HC) were clearly identified, each characterized by different CK expression. Medullary TEC were more heterogenous and shared common CK polypeptides either with subcapsular/perivascular TEC, cortical TEC, or HC, in most species.

Animals↗
PubMed1990

Ontogeny of rat thymic epithelium defined by monoclonal anticytokeratin antibodies.

Ontogenetic study on the expression of cytokeratin (CK) polypeptides within particular subsets of rat thymic epithelial cells (TEC) has been performed by a large panel of anti-CK monoclonal antibodies (mAbs) using the streptavidin-biotin immunoperoxidase method. Simultaneous presence of two or more CK subunits in the same TEC has been demonstrated by double immunofluorescence labeling. The obtained results showed that the expression of CK polypeptides in fetal and neonatal thymus differed from the adult patterns. The main difference was observed in expression of CK10, 18, and 19 polypeptides. During fetal ontogeny, CK10 and 18 are markers for most medullary TEC or a subset of medullary TEC, respectively, whereas CK19 is mainly a pan-TEC marker. In the adult animals, they are localized in the cortical and a subset of medullary TEC (CK18), subcapsular/perivascular and some medullary TEC (CK19), or in a subset of medullary TEC and Hasall's corpuscles (HC) (CK10). The switch in their expression in the cortex was observed during the first two weeks of postnatal life.

Animals↗
PubMed1990

[Immunomodulation during viral infections].

The paper provides a survey of immunomodulation mechanisms in the course of viral infections. The importance of viruses in the disturbance of immunological homeostasis has been pointed out. Virally induced immunomodulation can arise by: a mechanism of complete or abortive viral replication in the lymphocytes and macrophages, by soluble viral factors, by the influencing of antigen-presenting cells, and by excessive suppressor T-lymphocyte stimulation. Viral infections present a real danger to the integrity of the immunological system, and this demands a follow-up and an adequate interpretation of the arisen disorders.

Humans↗
PubMed1990

Immunohistochemical characterization of rat thymic non-lymphoid cells. II. Macrophages and granulocytes defined by monoclonal antibodies.

A panel of monoclonal antibodies (mAb) raised to antigens of rat thymic non-lymphoid cells (predominantly macrophages and granulocytes) was immunohistochemically characterized. Based on their staining patterns on cryostat thymic sections and double labellings using acid phosphatase activity, anti-cytokeratin mAb to exclude binding to epithelium or ED1 and ED2 mAb, specific for rat macrophages, antibodies were subdivided into four groups: (i) R-MC 39 mAb strongly reactive with macrophages in the cortex and cortico-medullary zone (CMZ) and weakly with some scattered macrophages in the medulla, blood vessels and thymocytes; (ii) R-MC 40, 41 and 42 mAb specific for cortical macrophages and most CMZ macrophages; (iii) R-MC 43 and 44 mAb predominantly recognizing CMZ and medullary macrophages; (iv) R-MC 45 mAb strongly labelling granulocytes and weakly a subset of macrophages throughout the thymus and isolated cells in the medulla. The obtained results show considerable heterogeneity within mobile thymic non-lymphoid cells and the presence of specific or common antigens in macrophages of particular topographic localization in the rat thymus.

Animals↗
PubMed1990

Genetic basis of resistance to trauma in inbred strains of mice.

In this study the resistance to mechanical, thermal, and radiation trauma in four inbred strains of mice (AKR, BALB/c, CBA, and C57Bl/6) was compared with the degree of genetic resemblance, by analyzing the allozyme variabilities of these strains. It was shown that the highest degree of genetic resemblance was among CBA and AKR strains, which correlated with a similar degree of resistance to trauma. On the other hand, BALB/c and C57Bl/6 strains expressed significant differences, both genetically and with respect to the responses to trauma. The hypothesis is introduced that the genetic determination of the resistance to trauma is based on: a) a polygenic control of general physiological homeostasis, with the possibility that b) some specific genes or single loci may contribute more than others to such adaptations of the strains tested.

Alleles↗
PubMed1990

[Kidney transplantation in high-risk patients].

Immunosuppression with Cyclosporine A in kidney transplantation, triple therapy (CyA + Imuran + corticosteroids) and plasmapheresis before and after kidney transplantation in high risk recipients (positive cytotoxic antibody, MLC at the level of non related persons), also in high risk patients (juvenile diabetes, patients over 50 years old). In 1988 we had done in our Centre, kidney transplantation in 52.8% (28: 53) in high and increased risk patients. Triple therapy with plasmapheresis before and after kidney transplantation (if the level of cytotoxic antibodies is over 15%) allows successful kidney transplantation in high risk kidney recipients. Patients with juvenile diabetes are also available kidney recipients with therapy and permanent regulation of blood sugar. The patients of the age group between 50-60 years should be considered as suitable for kidney transplantation.

Graft Survival↗
PubMed1989

Thymic response to thermal injury in mice: I. Alterations of thymocyte subsets studied by flow cytometry and immunohistochemistry.

The dynamics of thymocyte subset changes in mice subjected to sublethal thermal injury were studied in cell suspensions by flow cytometry and in situ by immunohistochemistry. Thermal injury caused acute thymic involution in the first 2 days which was the consequence of a considerable decrease in numbers of Thyl.2high+ CD4+ CD8+, cortical thymocytes. Medullary, Thyl.2low+ thymocytes were more resistant and their relative values increased. In the regenerative phase (2-14 days) the recovery of large CD4- CD8-, early thymocytes, mainly localized in the subcapsular area of the thymus, preceded the regeneration thymocytes of the cortical phenotype. Judged by the absolute numbers of medullary thymocytes it can be seen that CD4+ CD8- (T-helper/inducer cells) were more sensitive to the effect of thermal injury than CD4- CD8+ (T-suppressor/cytotoxic cells). While values of CD4+ CD8- cells were constantly and progressively lower during 2 weeks after thermal injury, absolute numbers of CD4- CD8+ cells showed cyclic changes with lower and higher values compared to controls. An increase in the numbers of CD4- CD8+ cells was found at day 6 after thermal injury.

Animals↗
PubMed1989

Immunohistochemical identification of six cytokeratin-defined subsets of the rat thymic epithelial cells.

Rat thymic epithelial cells (TEC) have been studied by a panel of monoclonal antibodies specific for single cytokeratin polypeptides or cytokeratin pairs. Using various combinations of single and double immunostainings 6 TEC subsets (CK types) were identified, each characterized by different cytokeratin expression. Subcapsular/perivascular TEC (TEC-CK type 1) share cytokeratins 7, 8, 19 with a subset of medullary TEC, while cortical TEC were reactive with anti-CK 8 and anti-CK 18 mAbs only (TEC-CK type 2). Additional 4 subsets were identified in the medulla; TEC-CK type 3 (CK 8 + 18 + 19 +), TEC-CK type 4 (CK 8 + 10 + 18 + 19 +), TEC-CK Type 5 (CK 8 + 10 + 10 +) and TEC-CK type 6 positive only with CK 8 of all above cytokeratins. This study extends the concept of TEC heterogeneity and might also be useful to further understanding of TEC origin, development and functions.

Animals↗
PubMed1988

Immunohistochemical characterization of rat thymic non-lymphoid cells. I. Epithelial and mesenchymal components defined by monoclonal antibodies.

Molecular microenvironmental heterogeneity within rat thymus was studied by a panel of 13 monoclonal antibodies (mAbs) raised to thymic epithelial (TE) cells and mesenchymal stroma. Based on their anatomical distribution patterns observed with immunohistological techniques on frozen sections and double immunostaining using anti-keratin antibodies to identify epithelium, they were subdivided into five groups: (i) pan TE cells antibodies (R-MC 2, 3 and 8); (ii) cortical TE cells antibodies (R-MC 13-17); (iii) antibodies detecting subcapsular and subtrabecular TE cells and most medullary TE cells (R-MC 18-20); (iv) antibody to Hassall's corpuscles (HC) and a small subpopulation of medullary TE cells (R-MC 22); (v) mesenchymal stroma antibody (R-MC 23). The obtained results show phenotypic heterogeneity of rat thymic epithelium and its distinction compared to mesodermal-derived compartment.

Animals↗
PubMed1987

The effect of the rat-cyclophosphamide serum on the rat hematopoietic tissue recovery, previously damaged by cyclophosphamide or by gamma-irradiation.

The effect of post-cyclophosphamide serum (post-CY serum) humoral activity in vivo, on the rat hematopoietic regeneration after damage either by cyclophosphamide (CY) or by gamma-irradiation was investigated. Three experimental groups of rats were studied. The first group was treated by a single high dose of CY (200 mg/kg), the second group was whole body irradiated by 6.5 Gy, and the third group was whole body irradiated by 3.5 Gy. Each group was subdivided into three subgroups. The first among subgroups received immediately after damage 0.5 cc post-CY serum, the second received 0.5 normal rat sera per animal. The third subgroup of rats was used as control. Post-CY sera were collected from the Wistar rats, 2.5 months old 48 hours after the treatment by high single dose by CY (300 mg/kg). Post-CY serum activity in comparison to normal serum activity was evaluated in vivo conditions. In order to take samples of peripheral blood, spleen and bone marrow, the animals were sacrificed 24 hours, 48 hours, 72 hours and seven days after treatment. The assessment of post-CY sera effect is accomplished by measuring of the proliferative capacity of splenic, as well as bone marrow cells, and by means of the RBC and WBC counts. The results obtained indicate substantial stimulative and proliferative activity of the post-CY sera, when compared to normal sera, particularly in the animals previously damaged with CY.

Animals↗
PubMed1977

[Analysis the incidence of HL-A-system antigen incidence in children treated for acute lymphoblastic leukemia].

Correlation between some histocompatible antigens and leukemia has been described both in men and in experimental animals. In 1970 Walford found an exceptionally high association between the illness and antigens of the HLA system in children with acute leukemia who had long life duration. It is therefore supposed that these antigens should not be associated with predispositional factors of the illness, instead, they are more likely to have influence over the course of the illness itself. Consequently, the authors have examined 15 children of various age who had acute leukemia. All children were examined for all antigens of the first and second HLA system, as well as for ABO and Rh genotype. The patients' blood was also checked for existence of cytotoxic antigens. Frequency of certain antigens and haplotypes was found in both children and their parents so that a comparison with antigen and haplotype frequency was also made.

ABO Blood-Group System↗