Expression of T cell antigen receptor and immunoglobulin genes in lymphoid organs visualized by in situ hybridization

Socioenvironmental stressors encountered during spaceflight partially affect the murine TCR-β repertoire and increase its self-reactivity

Spaceflights are known to affect the immune system. In a previous study, we demonstrated that hypergravity exposure during murine development modified 85% of the T-cell receptor (TCR)-β repertoire. In this study, we investigated whether socioenvironmental stressors encountered during space missions affect T lymphopoiesis and the TCR-β repertoire. To address this question, pregnant mice were subjected throughout gestation to chronic unpredictable mild stressors (CUMS), a model used to mimic socioenvironmental stresses encountered during space missions. Then, newborn T lymphopoiesis and the TCR-β repertoire were studied by flow cytometry and high-throughput sequencing, respectively. No change in thymocyte maturation or TCR expression were noted. TCR-β repertoire analysis revealed that 75% of neonate TCR-β sequences resulted from the expression of 3 variable (V)β segments and that this core repertoire was not affected by CUMS. However, the minor repertoire, representing 25% of the global repertoire, was sensitive to CUMS exposure. We also showed that the variable (diversity) joining [V(D)J] recombination process was unlikely to be affected. Finally, we noted that the CUMS neonatal minor repertoire was more self-reactive than the one of control pups. These findings show that socioenvironmental stressors such as those encountered during space missions affect a fraction (25%) of the TCR-β repertoire and that these stressors could increase self-reactivity.-Fonte, C., Kaminski, S., Vanet, A., Lanfumey, L., Cohen-Salmon, C., Ghislin, S., Frippiat, J.-P. Socioenvironmental stressors encountered during spaceflight partially affect the murine TCR-β repertoire and increase its self-reactivity.

In situ hybridization analysis of immunoglobulin heavy chain variable gene expression with family specific oligonucleotide probes

We have developed an improved in situ hybridization (ISH) technique for the analysis of human immunoglobulin heavy chain variable (V(H)) gene family expression in suspensions of human B lymphocytes. Oligonucleotide probes specific for framework region (FR) consensus germline sequences for each of the seven human V(H) gene families were designed and hybridization conditions were developed to accommodate the greatest degree of V(H) gene variation, maximize the sensitivity of transcript detection, and assure the specificity of the technique. The hybridization parameters were rigorously characterized by Southern hybridization to a panel of 30 V(H) cDNA clones and by ISH to 17 B cell lines expressing characterized V(H) genes. Results obtained with ISH using V(H) gene family and isotype-specific gene probes correlated well with histochemical measures of Ig gene product expression. Profiles of cellular V(H) gene expression were generated for mitogen stimulated peripheral blood B lymphocytes from six normal subjects. When compared with estimates of frequency of V(H) genes in the human germline, the results were consistent with a random pattern of V(H) family utilization.

Detection of T-cell receptor beta chain mRNA in frozen and paraffin-embedded biopsy tissue using digoxigenin-labelled oligonucleotide probes in situ

In situ hybridization techniques using a cocktail of digoxigenin-labelled T-cell receptor (TcR) constant (C) region beta oligonucleotide probes were used to detect TcR beta mRNA in frozen and paraffin-embedded tissue sections. The specificity of the C beta cocktail was confirmed by Northern blot analysis. The TcR C beta cocktail successfully hybridized to T cells in frozen and paraffin-embedded tissue obtained from patients with inflammatory arthropathies, B- and T-cell non-Hodgkin's lymphoma (NHL), and reactive tonsillitis, and showed staining patterns comparable to those obtained by conventional immunohistological detection of T cells. This is the first report of in situ studies using labelled TcR C beta oligonucleotide probes and may indicate the feasibility of investigating clonal T-cell populations using digoxigenin-labelled clonospecific probes in clinical samples in situ.

Murine models of autoimmune diabetes: nonspecific cytotoxic lymphocytes derived from pancreatic islets in the presence of IL-2

Our aim was to derive T lymphocyte lines that specifically recognize islet antigens in murine models of autoimmune diabetes. Islets of Langerhans infiltrated with lymphocytes were isolated either from mice previously injected with multiple low doses of streptozotocin or from NOD-WEHI mice and were cultured in the presence of the T cell growth factor, interleukin 2 (IL-2). With islets from both models of autoimmune diabetes, rapidly proliferating, large granular lymphocytes emerged after 7-10 days and destroyed the islets and other cells such as fibroblasts in the cultures. Cytotoxicity assays showed that these cells were capable of destroying both P815 and YAC-1 tumor cells. In contrast to lymphocytes present initially in the islet infiltrates which express predominantly the L3T4 marker, the large granular lymphocytes were shown to be Ly-2 positive. They also expressed the alpha beta T cell receptor and contained mRNA for the alpha beta T cell receptor demonstrable by in situ hybridization. While morphologically similar to NK cells these large granular lymphocytes bear T cell markers and destroy a broader range of targets. They may represent a minor population of T lymphocytes particularly responsive to IL-2 although other studies show that T cells generally can develop a similar phenotype after prolonged culture with IL-2. The lack of target cell specificity indicates that these IL-2-stimulated large granular lymphocytes are unlikely to mediate the immunopathogenesis of diabetes in these animal models.

Characterization of rat T cell precursors sorted by chemotactic migration toward thymotaxin

An established rat thymic cell line secretes a peptide in the 11 kd range called thymotaxin that attracts a small subset of juvenile rat bone marrow cells via a chemotactic mechanism. The selected cell subset (0.1% of the total bone marrow) is composed of low-density lymphoid cells that do not replicate, and display an immature Thy-1+T-B- phenotype. Thymotaxin-responding cells do not grow in semi-solid cultures under hemopoietic growth factors stimulation, and survive only in coculture with thymic stroma under steroid-free conditions. This stroma mimics the thymic microenvironment and allows a fraction of responding bone marrow cells to acquire T cell differentiation markers and to synthesize transcripts of the TCR alpha and beta chains. Chemotactic migration toward thymic epithelial cell peptides can be used in vitro to sort pre-T cells from the rat bone marrow. The sorted T cell precursors are resting stem cells possibly committed to lymphoid lineage.

Is the Hodgkin cell a T- or B-lymphocyte? Recent evidence from geno- and immunophenotypic analysis and in-vitro cell lines

The cellular derivation of Hodgkin (H) and Reed-Sternberg (RS) cells remains a controversial issue. A large body of conflicting results in the literature led to a variety of discordant speculations. The application of immunophenotyping, molecular biology and tissue culture provided additional means for investigations on the nature of H-RS cells. Using immunoenzymatic staining with monoclonal antibodies (McAbs) at the single cell level, H-RS cells from many, albeit not all cases, were shown to be positive for T- and/or B-cell markers; none of the cases were labelled by anti-myeloid or anti-monocyte/macrophage McAbs. A common feature of the otherwise heterogeneous immunoprofile is the expression of activation and proliferation antigens besides HLA-DR class II antigen and the X-hapten. Clonal rearrangements of T-cell receptor or immunoglobulin chain genes were found in 22 per cent of cases. The low frequency of positive samples might be due to the commonly low number of H-RS cells in the total population which can lay below the threshold of sensitivity for genotypic analysis. Several cell lines containing H-RS-like cells have been established. These cell lines have geno- and immunophenotypic characteristics of T- or B-cells, but lack properties of myeloid cells or monocytes/macrophages. In the absence of evidence in support of an origin from monocytes/macrophages or other non-lymphoid cells the here reviewed data, which are based on geno- and immunophenotypic analysis of fresh and cultured H-RS cells, provide a lead to a lymphoid derivation of H-RS cells.

Hepatic expression of rat P450 mRNA assessed by in situ hybridization to oligomer probes

Cell-specific chemical toxicities may be influenced by P450-catalyzed biotransformation reactions. We have undertaken an analysis of P450 expression in isolated rat liver sections to assess better the cellular distribution of P450 gene products. Discriminatory 18-mer oligodeoxynucleotides directed to the phenobarbital (PB) inducible P450s, P450IIB1 (P450b) and P450IIB2 (P450e), were employed as probes for in situ hybridization experiments. With these techniques we demonstrate that P450b and P450e mRNAs are each expressed in the hepatic lobule with similar spatial distribution. In animals pretreated with PB, only cells within the immediate periportal region were refractory to induction. Based on autoradiographic grain densities, responsive hepatocytes accumulated P450b mRNA at levels exceeding that for P450e. We employed in situ hybridization methodology in combination with Northern blot analyses to compare the expression of these mRNAs in two rat strains, Sprague-Dawley and Marshall 520/N (the latter being deficient in the synthesis of P450e isozyme; Rampersaud and Walz, 1987). These strains provided valuable comparative models, demonstrating the specificity and sensitivity of the oligomer probes. The continued development of in situ hybridization methodologies, especially when used in conjunction with synthetic oligomer probes, will permit a detailed analysis of P450 expression in different tissues, under a variety of chemical exposures, and may be a valuable adjuvant to the prediction of target organ toxicities.

Immunoglobulin gene expression is a normal differentiation event in embryonic thymocytes

By in situ hybridization to frozen sections of mouse embryos, we have localized cells transcribing the Ig C mu gene during ontogeny. Transcripts were detected from before day 14 of gestation in individual pre-B cells in the liver and, surprisingly, in a large proportion of thymocytes between days 15 and 18. The level of mu RNA sequences in the thymus at day 17 was much higher than has been observed for adult thymocytes; from grain counts, the amount of mu RNA was similar to that observed for Ti gamma RNA. These findings suggest that Ig and Ti genes are under similar transcriptional controls during Ti gene recombination and that elevated mu RNA production is a normal event early in the intrathymic differentiation of T cells.