Expression of the CD28 costimulatory molecule on subsets of murine intestinal intraepithelial lymphocytes correlates with lineage and responsiveness

The CD28 antigen has been recently demonstrated to be a costimulatory molecule and is expressed by almost all thymic and peripheral T cell receptor (TcR) α^δ+ and γ^λ+ cells in the mouse system. We show here that expression of CD28 is heterogeneous among murine intestinal intraepithelial lymphocytes (IEL). Whereas some TcR αβ-expressing IEL subsets such as CD4⁺8^? and CD4^?8α⁺β⁺ cells express CD28 at the same levels as their phenotypic counterparts in lymph node, other subsets of TcR αβ cells (including CD4^?8α⁺β^? and CD4⁺8αβ⁺β cells) as well as TcR γ^λ+ IEL fail to express CD28. Parallel experiments using aged BALB/c-nu/nu mice indicated that CD28 expression patterns among IEL are quite similar to those of normal BALB/c mice. Furthermore, forward light scatter analysis showed that CD28^? cells are considerably larger than CD28⁺ cells in the gut, although cycling cells were rare in both subsets. Finally CD28^? cells in the gut did not proliferate or produce IL-2 upon stimulation by anti-CD3 monoclonal antibodies (mAb) and phorbol 12-myristate 13-acetate, whereas CD28⁺ cells in the gut and lymph nodes responded to these stimuli. The response of the CD28⁺ cells was enhanced by anti-CD28 mAb. These results suggest that CD28^? IEL (CD4-8α⁺β^? cells, and some CD4⁺8α⁺β^?cells) may follow a different developmental pathway from that of CD28⁺ IEL in a thymus-independent environment, and that expression of CD28 correlates with responsiveness of the cells to triggering via the TcR-CD3 complex.     

Development of T cells in SCID mice grafted with fetal thymus from AKR mice or F344 rats

To examine the development of T cells within an allogeneic or xenogeneic environment, we engrafted the fetal thymus from AKR mice or F344 rats under the kidney capsule of SCID mice (mTG and rTG mice). T lymphopoiesis developed in SCID mice 2 months after transplantation, although the ratio of CD4/CD8 in both experimental groups was different from that of normal control. T cells in mTG mice did not show in vitro proliferation or cytotoxicity against either host-type C.B-17 (H-2^d) or donor-type AKR (H-2^k) cells, while they exerted potent activities against third-party BIO (H-2^b) cells. In contrast, T cells in rTG mice exhibited proliferation against both host-type C.B-17 and donor-type F344 rat cells. Consistently, graft-vs.-host disease symptoms developed in these mice and histological examination showed impressive infiltration of lymphocytes into the skin or into the mucosal layers of the stomach. Activated state of T cells in rTG mice was also evidenced by the positive expression of interleukin-2 receptor. Taken together, fetal thymus appears to contain progenitor cells which are sufficient for in vivo reconstitution of T lymphopoiesis, but species-specific environment is important for the induction of tolerance. In mTG mice, Vβ6⁺ T cells reactive to donor Mls^a determinants and Vβ3⁺ T cells reactive to host Mls^c determinants were deleted, suggesting that tolerance was regulated mainly by clonal deletion. By contrast, Vβ11⁺ T cells reactive to Mls^f determinants were not deleted possibly due to the lack of their ligands.     

Pentoxifylline attenuates the development of hyperalgesia in a rat model of neuropathic pain

Pentoxifylline, a non-specific cytokine inhibitor, has shown to be beneficial in inflammatory pain in both experimental and clinical studies. The present study demonstrates for the first time, to our knowledge, the antihyperalgesic effect of pentoxifylline in the neuropathic pain using L5 spinal nerve transection rat model. In a preventive paradigm, pentoxifylline (12.5, 25, 50, or 100 mg/kg intraperitoneally) was administered systemically daily, beginning 1 h prior to nerve transection. Pentoxifylline (50, or 100 mg/kg i.p.) produced significant decrease in the mechanical and thermal hyperalgesia. However, pentoxifylline (100 mg/kg i.p.) did not influence the paw pressure thresholds and paw withdrawal latency in sham-operated rats. In order to understand the possible antinocicieptive effect of pentoxifylline in neuropathic pain, we examined the level of TNFα, IL-1β, IL-6 and IL-10 protein in the contralateral brain on day 7 post-transection. Pentoxifylline administration resulted in a dose-dependent reduction of the production of proinflammatory cytokines like TNFα, IL-1β and IL-6, and enhancement of IL-10. Furthermore, we investigated the activity of nuclear factor kappa B (NF-κB) in the contralateral brain on days 7 after surgery. In accordance with the change of proinflammatory cytokines, Pentoxifylline (50 or 100 mg/kg) significantly inhibited the activation of NF-κB in the brain. This research supports a growing body of literature emphasizing the importance of neuroinflammation and neuroimmune activation in the development of neuropathic pain states, and the potential preventive value of pentoxifylline in the treatment of neuropathic pain.     

Abnormal T cell responses to bacterial superantigens in Behçet's disease (BD)

This study examines the nature of T cell hypersensitivity in BD. Highly purified T cells from 32 BD patients, from 29 rheumatoid arthritis (RA) patients and from 14 healthy individuals were cultured with various concentrations of Staphylococcal enterotoxins (SE) B and C₁ in the presence of monocytes for 5 days, after which the production of interferon-gamma (IFN-γ) was assessed. High concentrations of SE (1 ng/ml) stimulated BD T cells as well as control T cells to produce comparably high amounts of IFN-γ, whereas low concentrations of SE (1 pg/ml) stimulated BD T cells much more effectively than normal or RA T cells. The hypersensitivity of BD T cells to low concentrations of SEC₁ was restored with RA monocytes instead of BD monocytes, whereas BD monocytes could not elicit the SEC₁-induced IFN-γ production of RA T cells. Moreover, there were no significant differences between BD T cells and RA T cells in monocyte-independent IFN-γ production stimulated with low or high concentrations of immobilized anti-CD3, or in the monocyte-mediated enhancement of IFN-γ production stimulated with a low concentration of immobilized anti-CD3. These results confirm that T cell hypersensitivity is not confined to certain specific antigens in BD. More importantly, the data strongly suggest that abnormalities in signal transduction triggered by perturbation of T cell receptors, but not in that induced by cross-linking of CD3 molecules nor in that delivered through costimulation molecules, play an important role in the pathogenesis of BD.     

Anti-CD3 induces bi-phasic apoptosis in murine intestinal epithelial cells: possible involvement of the Fas/Fas ligand system in different T cell compartments

Recent studies have suggested that Fas-mediated apoptosis is involved in the pathogenesis of intestinal injury. In this study, we determined the role of Fas/Fas ligand (FasL) interactions in different T cell compartments using a murine model of small intestinal injury. An intraperitoneal injection of 145-2C11 (anti-CD3) antibody into C3H/HeN, BALB/c and MRL mice induced mucosal flattening and rapid, bi-phasic intestinal epithelial cell (IEC) apoptosis, which was detected by conventional light and electron microscopy and by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. In the first, early phase, villous apoptosis was observed up to 4 h after injection, and in the second, later phase, apoptotic crypt cells gradually accumulated for up to 24 h. The early and later phases of apoptosis were reduced in lpr/lpr and nude mice compared with those in control strains. In addition, the kinetics of Fas-mediated killer activity induced by the antibody injection were different between intestinal intraepithelial lymphocytes (IEL) and splenocytes (SPL) and seemed to correlate with the bi-phasic occurrence of the apoptosis. Finally, the transfer of intestinal IEL from euthymic to nude mice induced both phases of apoptosis, whereas SPL induced the second phase's crypt apoptosis only by the antibody injection. Together, these results suggest the involvement of Fas-mediated killer activity of thymus-derived T cells in different compartments. Namely, T cell populations in different compartments are differentially involved in the induction of IEC apoptosis and contribute to the complex pathogenesis of immune-mediated intestinal injury in which Fas/FasL interactions may play a critical role.     

Immunological profile of peripheral blood lymphocytes and monocytes/macrophages in Kawasaki disease

Kawasaki disease (KD) is an acute illness of early childhood characterized by prolonged fever, diffuse mucosal inflammation, indurative oedema of the hands and feet, a polymorphous skin rash and nonsuppurative lymphadenopathy. The histopathological findings in KD comprise panvasculitis with endothelial necrosis, and the infiltration of mononuclear cells into small and medium-sized blood vessels. The levels of many proinflammatory cytokines, chemokines and adhesion molecules can be elevated in sera from children with KD at the acute stage. Although many immunological studies on KD involving peripheral blood have been reported, the data obtained remain controversial. This review focuses on the immune response of peripheral blood lymphocytes and monocytes/macrophages during acute KD.     

The distribution of cathepsin B in human tissues

Cathepsin B is a lysosomal enzyme of importance in many physiological and pathological processes. Its distribution in human tissues was studied by an indirect immunoperoxidase method. Cathepsin B was demonstrated in macrophages, hepatocytes, renal tubules, gastrointestinal epithelium and fibroblasts, confirming previous studies. It was demonstrated for the first time by immunohistology in several other tissues, especially stratified squamous epithelium, transitional epithelium, salivary glands, pancreas, central and peripheral neuronal cell bodies, trophoblast and all endocrine organs. Widespread distribution of cathepsin B has been postulated several times but this is the fullest evidence that the enzyme indeed occurs in many organs. In pathology cathepsin B has so far been thought to be involved in demyelination, emphysema, rheumatoid arthritis and neoplastic infiltration.