Mice deprived of exogenous antigenic stimulation develop a normal repertoire of functional T cells.

The development of T cells and the selection of the TCR repertoire in the absence of exogenous antigenic stimulation were investigated. For this purpose germfree BALB/c mice fed an ultrafiltered solution of chemically defined low m.w. nutrients (GF-CD) were used. Previous studies on B cell development and differentiation in GF-CD mice have demonstrated a high reduction in the number of cells secreting Ig of the non-IgM isotypes but an Ig-VH gene usage and a B cell specificity repertoire that is substantially different from that observed in conventional adult mice and more closely resembles that of neonatal conventional mice. In contrast, the present comparison of the various lymphocyte populations in the thymus, lymph nodes, and spleen from GF-CD and conventional mice using flow cytometry analysis revealed no significant differences. Analysis of the TCR-V beta expression on both mature thymocytes and lymph node T cells showed a high degree of similarity between GF-CD and conventional mice. These findings indicate a marked difference in the influence of exogenous antigenic stimulation on the development of B and T cells. Additionally, development in an environment free of exogenous antigenic stimulation allows for full functional maturation of T cells to occur, because MLC showed that GF-CD splenic T cells could mount allogeneic responses in a way similar to T cells generated in a conventional environment. Most importantly, full Th cell function is generated, because activation of GF-CD spleen cells by cross-linking with mAb against CD3 resulted in the induction of cells secreting IFN-gamma and Ig of the non-IgM isotypes, which cannot be detected in GF-CD sera. These findings demonstrate that functional T and B cells develop in mice that have not been exposed to exogenous Ag, and that the TCR repertoire, in contrast to the B cell compartment, is predominantly shaped by endogenously expressed Ag.     

The effect of corticosteroids upon the number and organ distribution of "background" immunoglobulin-secreting cells in mice

The influence of the synthetic corticosteroid dexamethasone sodium phosphate (DEXA) upon the immunoglobulin (Ig)-secreting cells was studied in not intentionally immunized BALB/c mice. This was done for IgM-, IgG-, and IgA-secreting cells in spleen, mesenteric lymph nodes (MLN), and bone marrow (BM). A single injection of DEXA (16 to 144 mg/kg body wt) markedly reduced the number of Ig-secreting cells in spleen and MLN within 1 day, but hardly affected their number in the BM. The decrease was immediately followed by a recovery and, at the highest doses and especially in MLN, by an overshoot. Two weeks after the initial decrease a second decrease was found. When mice were subjected to daily treatment with DEXA during 1 week, initially a recovery pattern was found in spleen and MLN similar to that found after a single injection of a high dose. In this case, however, the effects were less dose dependent, and the overshoot reaction was followed by a period of subnormal numbers of Ig-secreting cells which lasted at least 1 week. This late effect of DEXA not only occurred in spleen and MLN, but also in the BM. The most prominent effect of daily treatment with DEXA was the long-lasting decrease of the number of IgG-secreting cells starting 1 week after withdrawal of treatment. This decrease was associated with a severely decreased serum IgG level.     

The influence of exogenous DNA of different origin on the mitosis and chromosomes of irradiated meristematic cells ofVicia faba

In this paper we compare the influence of heterologous and isologous DNA on the radiation damage repair of primary root meristematic cells ofVicia faba. Roots, irradiated by exposure of 150 r were cultivated at different time intervals either in tap water, or in a solution of heterologous or isologous DNA. In comparing mitotic activity of meristematic cells it was found that both types of DNA studied enhance the recovery of irradiated cells. The frequency of postmetaphase chromosomal aberrations of irradiated cells was influenced also by post-irradiation action of exogenous DNA. While heterologous DNA exhibited synergical effect with radiation in the sense that it increased the post-irradiation incidence of aberrations in all time intervals studied, isologous DNA had a strong repair effect—the application caused a significant decrease of the percentage of post-metaphase aberrations. Both kinds of DNA caused changes in the relation of chromosome to chromatid aberrations; a higher percentage of chromatid aberrations was registered. The study of the distribution of aberrations between large and small chromosomes ofVicia faba showed that the post-irradiation application of heterologous DNA increases damage of small chromosomes while isologous DNA caused an increased repair ability in this chromosomal group.     

The influence of exogenous eicosanoids on the radiation response of cultured bovine aortic endothelial cells

The radioprotection by several eicosanoids was investigated in cultures of bovine aortic endothelial cells. One hour before irradiation (0-500 cGy, 137Cs gamma rays) 10 micrograms/ml of PGD2, PGE1, PGI2, misoprostol (PGE1-analog), 16,16-dimethyl PGE2, PGA2, or 1 microgram/ml LTC4 was added. Radiation decreased incorporation of [3H]thymidine at 4 h, cell number/culture at 24 h, and cell survival as measured by colony formation. Under these conditions the eicosanoids were not radioprotective. Two eicosanoids, PGD2 and PGA2, appeared to be toxic. Because receptors might mediate eicosanoid-induced radioprotection, radioligand binding of PGE2 and LTC4 and levels of adenosine 3',5'-cyclic monophosphate (cAMP) were measured. Evidence for a receptor was equivocal; there was nonspecific binding and metabolism of LTC4. The level of cAMP was elevated by 16-16-dimethyl-PGE2 in the presence of isobutyl methylxanthine; however, this combination of the prostaglandin and the methylxanthine was not radioprotective. These investigations suggest that an elevated cAMP level alone does not lead to eicosanoid-induced radioprotection of bovine aortic endothelial cell monolayers in vitro.     

Reproductive success of males of the ICR outbred line during propagation against the background of antigenic stimulation

Diversity of viruses, bacteria, microscopic fungi, and endo- and ectoparasites is an inevitable environmental factor that influences the host reproduction and that is determined not only by negative effects of infectious diseases but also by activation of protective mechanisms, which provide a confrontation to the pressure of parasites. In the present work, hemocyanin was injected into males of the ICR outbred line in order to study reproductive consequences of antigenic stimulation of males. Intact females were added to control and antigen-stimulated males at the initial stage of antibody formation. During 6 days of combined keeping, a significantly greater amount of ovulated egg cells and living embryos were registered in the females added to males that were injected with hemocyanin compared with that theoretically expected for equal reproductive yield. Females covered by antigen-stimulated males bred larger embryos compared with those in the control. Indices of female fertility depended on prevalence of cellular (Th1) or humoral (Th2) immune responses in antigen-stimulated males. Shift of Th1/Th2 balance resulted in higher preimplantation embryonic losses in females covered by males with a prevalence of cellular immune response; however, they bred larger embryos. Thus, it was established that activation of the immune system in males does not influence their reproductive abilities. This allows us, on the one hand, to explain the contribution of protective reactions of the organism in the increase in fertility of the mammals that inhabit territories with high specific abundance of parasites; on the other hand, it demonstrates new ways of the management of the reproduction of animals bred under human control.     

In vitro activation of CD8 interphotoreceptor retinoid-binding protein-specific T cells requires not only antigenic stimulation but also exogenous growth factors

In a previous study, we demonstrated that immunization with the uveitogenic peptide interphotoreceptor retinoid-binding protein (IRBP) 1-20 induces both CD4 and CD8 uveitogenic T cells in the B6 mouse. In the current study, we determined the role of the CD8 IRBP-specific T cells in the pathogenesis of experimental autoimmune uveitis. We also determined the conditions that facilitated the activation of CD8 autoreactive T cells. Our results showed that the beta2-microglobulin(-/-) mouse had a greatly decreased susceptibility to induction of experimental autoimmune uveitis by adoptive transfer of IRBP-specific T cells from B6 mice. We also showed that unlike CD4 autoreactive T cells, activated CD8 autoreactive T cells produced only a limited number and amounts of growth factors. As a result, in the absence of exogenously supplied growth factor(s), CD8 T cell activation and expansion were aborted. However, the growth and expansion of triggered CD8 autoreactive T cells could be supported by various cytokines. In addition to factors produced by activated CD4 autoreactive T cells, factors produced by nonlymphoid cells, such as IL-7 and IL-15, and unidentified factors in the culture supernatants of astrocytes and retinal pigment epithelial cells support the CD8 autoreactive T cells as well. Finally, we showed that, although several cytokines augmented the CD8 T cell response in vitro, different cytokines appeared to act on different CD8 subsets or on different activation/differentiation phases of CD8 autoreactive T cells. As a result, cytokines, such as IL-7, supported the proliferation and survival of CD8 IRBP-specific T cells, while others had only a growth-promoting effect.     

The range of antigenic specificity of Bifidobacterium peptidoglycan]

The antigenic relationships of Bifidobacterium bifidum 1 peptidoglycans with different strains of this species (LVA-3, 791, GO-4), bifidobacteria of other species (B. adolescentis GO-13, B. breve 79-38, B. lactentis 79-41, B. longum GO-3) and bacteria of remote taxonomic groups (Streptococcus faecalis 6-3. Staphylococcus aureus COM 885, S. epidermidis COM 2124. Lactobacillus plantarum 1, Escherichia coli M-17) were studied on the basis of a highly sensitive test system permitting the registration of normal human antibodies to peptidoglycans. The level of cross reactions with staphylococci and streptococci correspond to intraspecific and antigenic affinity to L. plantarum and E. coli was considerably less pronounced. Copying a number of epitopes of bifidobacteria, S. aureus peptidoglycan seems to possess additional antigenic determinants which participate in the formation of immunological responsiveness in man.     

The proteoglycan repertoire of lymphoid cells

Proteoglycans have been studied to a limited extent in lymphoid cells. In this study we have investigated the expression of proteoglycans in B-cells, CD4+ T-cells, CD8+ T-cells, natural killer cells, as well as in nine different cell lines established from patients with lymphoid malignancies. Serglycin was the major proteoglycan expressed at mRNA level by the primary lymphocytes. None of the syndecans or glycpicans was detected at mRNA level in the primary lymphocytes, except for syndecan-4 in CD4+ T-cells and CD8+ T-cells. All lymphoid cell lines expressed serglycin mRNA, as well as one or several members of the syndecan and glypican families. Further, increased synthesis of proteoglycans was found in the cell lines compared to the primary lymphocytes, as well as the presence of heparan sulfate on the cell surface of five of the cells lines. Western blot analysis showed a close correlation between serglycin mRNA level and expression of serglycin core protein. Our results show that serglycin is a major proteoglycan in all the normal lymphoid cells and that these cells carry little, or none, proteoglycans on the cell surface. Serglycin was also a major proteoglycan in the malignant lymphoid cells, but these also expressed one or more types of cell surface proteoglycans. Thus, malignant transformation of lymphoid cells may be followed by increased synthesis of proteoglycans and expression of cell surface proteoglycans.     

Clonotype and repertoire changes drive the functional improvement of HIV-specific CD8 T cell populations under conditions of limited antigenic stimulation

Persistent exposure to cognate Ag leads to the functional impairment and exhaustion of HIV-specific CD8 T cells. Ag withdrawal, attributable either to antiretroviral treatment or the emergence of epitope escape mutations, causes HIV-specific CD8 T cell responses to wane over time. However, this process does not continue to extinction, and residual CD8 T cells likely play an important role in the control of HIV replication. In this study, we conducted a longitudinal analysis of clonality, phenotype, and function to define the characteristics of HIV-specific CD8 T cell populations that persist under conditions of limited antigenic stimulation. Ag decay was associated with dynamic changes in the TCR repertoire, increased expression of CD45RA and CD127, decreased expression of programmed death-1, and the emergence of polyfunctional HIV-specific CD8 T cells. High-definition analysis of individual clonotypes revealed that the Ag loss-induced gain of function within HIV-specific CD8 T cell populations could be attributed to two nonexclusive mechanisms: 1) functional improvement of persisting clonotypes; and 2) recruitment of particular clonotypes endowed with superior functional capabilities.     

The human miRNA repertoire of different blood compounds

Background

MiRNAs from body fluids gain more and more attraction as biomarker candidates. Besides serum, patterns from whole blood are increasingly considered as markers for human pathologies. Usually, the contribution of different cell types to the respective signature remains however unknown. In this study we provide insights into the human miRNome of different compounds of the blood including CD3, CD14, CD15, CD19, CD56 positive cells as well as exosomes.

Methods

We measured the miRNA repertoire for each cell type and whole blood for two individuals at three time points over the course of one year in order to provide evidence that the cell type miRNomes can be reproducibly detected.

Results

For measurements repeated after 24 hours we found on average correlation of 0.97, even after one year profiles still correlated with 0.96, demonstrating the enormous stability of the cell type specific miRNomes. Highest correlation was found for CD15 positive cells, exceeding Pearson correlation of 0.99. For exosomes a significantly higher variability of miRNA expression was detected. In order to estimate the complexity and variability of the cell type specific miRNomes, we generated profiles for all considered cell types in a total of seven unaffected individuals. While CD15 positive cells showed the most complex miRNome consisting of 328 miRNAs, we detected significantly less miRNAs (186, p = 1.5*10^-5) in CD19 positive cells. Moreover, our analysis showed functional enrichment in many relevant categories such as onco-miRNAs and tumor miRNA suppressors. Interestingly, exosomes were enriched just for onco-miRNAs but not for miRNA tumor suppressors.

Conclusion

In sum, our results provide evidence that blood cell type specific miRNomes are very consistent between individuals and over time.     

The influence of the thermal factor on the antigenic properties of skin]

Results of immunochemical studies of normal and thermally-treated human skin in vitro showed at least 2 of 4-5 organospecific dermal antigens to be thermostable-they withstood heating at 100 degrees C for 3 minutes; 2 or 3 antigens were thermolabile. The thermostable antigens possessed electrophoretic migration in the field of alpha1- and gamma-globulins. The burn eschar was found to retain one of the two thermostable oranospecific antigens together with the loss of thermolabile antigen.     

The role of B cell proliferation in the generation of immunoglobulin-secreting cells in man

The relationship of B cell proliferation and the generation of immunoglobulin-secreting cells (ISC) was explored in vitro by examining the effect of hydroxyurea (HU), an inhibitor of cellular DNA synthesis, on the generation of ISC from human peripheral blood mononuclear cells (PBM). HU completely inhibited the capacity of PBM to generate ISC in response to pokeweed mitogen (PWM) and other polyclonal B cell activators. Inhibition resulted from an effect on B cell proliferation, because HU also prevented the generation of ISC in cultures of purified B cells supplemented with either T cell supernatants or mitomycin C-treated T cells. Inhibiting B cell proliferation by treating them with mitomycin C before culture also abolished the generation of ISC. When ISC were enumerated after a 7-day incubation with PWM, the addition of HU as late as day 6 of culture was found to inhibit responsiveness markedly. This suggested that those cells that had acquired the capacity to secrete lg were actively dividing, and continued division was necessary for ongoing lg secretion. To examine this possibility, experiments were carried out in which responsiveness was assayed on a daily basis. ISC could be detected after a 3- or 4-day incubation and reached maximum at day 6 or 7. Addition of HU on days 3 to 7 caused a highly significant reduction in the number of ISC within 24 hr. ISC did not begin to show resistance to the effects of HU until later in culture. This observation supported the conclusions that ISC were a rapidly cycling cell population and that ongoing lg secretion, as well as expansion in the number of ISC, depended on continued proliferation of the ISC. To confirm directly that ISC were a cycling cell population, PBM were cultured with PWM for 6 days, fixed, stained for both cytoplasmic lg and DNA content, and analyzed on the fluorescence-activated cell sorter. This method made it possible to quantitate the DNA content of individual lg-synthesizing cells and thus to determine their position in the cell cycle. As many as 40% of cytoplasmic lg-positive cells were found to be in the S, G2, or M phases of the cell cycle. These data indicate that ISC generated in man after in vitro stimulation with a number of polyclonal activators are not stable terminally differentiated lg-secreting plasma cells but rather an actively cycling lg-secreting population. Furthermore, the results indicate that proliferation of the ISC themselves plays an important role in determining the magnitude of the resultant antibody response.