Luis Alonso

Interleukin-7 treatment promotes the differentiation pathway of T-cell-receptor-alpha beta cells selectively to the CD8+ cell lineage.

In this report we have studied the influence of interleukin‐7 (IL‐7) on thymocyte differentiation by evaluating the effects of IL‐7 on the generation of T‐cell receptor‐αβ (TCR‐αβ) and TCR‐γδ thymocyte subpopulations in rat fetal thymus organ culture. IL‐7 enhanced the differentiation pathway of TCRαβ thymocytes, first increasing the numbers of immature CD8+ cells, and later those of both CD4+CD8+ and mature thymocytes. The kinetics of thymocyte migration out of thymic lobes was also accelerated, and the average number of mature TCR‐αβhi emigrants per day was increased in the presence of IL‐7. Moreover, mature CD4−CD8+ thymocytes were preferentially generated after IL‐7 administration. This TCR‐αβhi cell population was not actively dividing, indicating that IL‐7‐promoted thymocyte differentiation was selective to the CD8 cell lineage. Distribution of some TCR‐Vα and TCR‐Vβ segments among mature thymocytes was also modified in IL‐7‐treated thymic lobes. On the contrary, the maturation of TCR‐γδ was not affected by IL‐7 addition during the first days of culture, but their numbers sharply increased by day 6 of culture. These results were confirmed with IL‐7‐treated cultures for 24u2003hr, showing that IL‐7 responsiveness was acquired by TCR‐γδ cells late in thymus ontogeny. The present results thus indicate a key role for IL‐7 in the maturation of TCR‐αβ thymocytes and the expansion of thymic TCR‐γδ cells.

CHANGES IN THE BLOOD THYMUS BARRIER OF ADULT RATS AFTER ESTRADIOL TREATMENT

The accessibility of the thymus parenchyma for relatively large Mw (+/- 150 Kd) proteins has been studied by the intravenous injection of monoclonal antibodies (mAbs) specific either for all T cells (His-17) or MHC class II molecules (His-19) in control and estradiol benzoate (EB)-treated adult Wistar rats. In controls, the transcapsular route rather than cortical capillaries seems to be involved in the entry of molecules into the thymus. By contrast, a specific staining for either T cells (His-17) or MHC class II molecules (His-19 positive cells) disappears almost completely from the thymic cortex of EB-treated rats except in the immediate subcapsular epithelial cell layer. In these rats, T cells and epithelial cells intimately associated to blood vessels from both inner cortex and corticomedullary border showed additional staining with the respective mAbs confirmed by electron microscopy. The disappearance of the transcapsular route together with the increased vascular permeability of cortical blood vessels would be related to the reinforcement of the subcapsular epithelial cell layer and to direct effects of EB on vascular endothelia, respectively. These results are discussed in relationship to the cell migration into and out of adult thymus, as suggested by the changes in intrathymic T cell subsets evaluated by flow cytometry.

Ultrastructural changes in the adult rat thymus after estradiol benzoate treatment.

Although numerous authors have correlated high levels of circulating estrogens with thymic involution, a systematic analysis to date on the histological changes affecting the thymus gland in that situation is lacking. In the present study we report both histological and ultrastructural changes occurring in the thymus of adult Wistar rats which received a single dose either of 100 micrograms or 500 micrograms of estradiol benzoate. Both doses induced thymic involution which correlated well with histological changes observed in the lymphoid populations but also with profound modifications in the thymic epithelial component. Moreover, intrathymic erythro-and granulopoiesis, increased numbers of both macrophages and plasma cells, and important variations in the thymic vascular permeability occurred in estradiol benzoate treated rats. These results are discussed from the perspective that changes in both the non-lymphoid cell components of thymic microenvironments and vascular permeability are essential to understand the general effects of sex steroids on the immune system.

Additional symmetries, Virasoro constraints and string equations for super KP hierarchies

Abstract With the use of vacuum functions for the super KP hierarchies, Manin-Radul and Jacobian versions, we study the additional symmetries for such integrable hierarchies. The constraints arising from super Virasoro symmetries combined with bosonic and fermionic reductions under super KP flows are analyzed and the corresponding string equations are characterized.

The IL-2/IL-2-Receptor Complex in the Maturation of Rat T-Cell Progenitors

On the basis of both the interleukin-2-receptor (IL-2R) α-chain expression on 16-day-old fetal rat thymocytes and the occurrence of interleukin-2 (IL-2) mRNA-containing cells early during rat thymus ontogeny, we have investigated the possible role of IL-2/IL-2R complex in rat T-cell maturation. For this purpose, we analyzed the effects of the addition of either recombinant rat IL- 2 or anti-CD25 (OX-39)-blocking monoclonal antibodies to fetal thymus organ cultures (FTOC), established from 16-day-old rat embryos. IL-2 stimulated the growth of thymocytes and, as a result, induced T-cell differentiation, whereas OX-39 mAb blocked the maturation of thymic-cell progenitors. Accordingly, these results support the involvement of IL-2/IL-2R complex in rat Tcell development.

A preliminary general testing method based on genetic algorithms

We present a testing methodology to find suitable test suites in environments where the application of each test to the implementation under test (IUT) might be very expensive in terms of cost or time. The method is general in the sense that it keeps very low the dependence on the underlying model (e.g. finite state machines, timed automata, Java programs, etc). A genetic algorithm (GA) is used to find optimal test suites according to cost and distinguishability criteria.

Antibody-Forming Cells (AFCs) in the Lung Lymphoid Tissue After Primary and Secondary Immunization Through Different Routes:A Semiquantitative Analysis in Adult Rats Using T Dependent (TNP-KLH) and T-Independent Antigens (TNP-LPS)

Despite pioneer reports emphasizing the mutual resemblances of the bronchus-associated lymphoid tissue (BALT) and the gut-associated lymphoid tissue (GALT), so claiming the relationship of BALT to the so-called mucosa-associated lymphoid tissue (MALT), the evidence is merely circumstantial. To date, there are important differences in the histological organization of both tissues1,2. The lymphoepithelium condition of the epithelium covering the lung lyraphoid aggregates can only be observed in locally immunized animals and even in that situation the existence of M-like cells in the epithelium is controversial2,3. Moreover, germinal centers have only been reported in the BALT after extensive immunization2.