Recombinant tumor necrosis factor enhances the locomotion of memory and naive B lymphocytes from human tonsils through the selective engagement of the type II receptor

Recent studies performed in mice knocked out for the tumor necrosis factor (TNF ), the lymphotoxin-alpha, or the type I TNF receptor (R), genes have shown that these animals display gross defects in germinal center (GC) formation, suggesting that members of the TNF and TNFR superfamilies are involved in the control of B-cell migration. Based on these premises, we have here investigated the effects of human recombinant (r) TNF on the polarization and locomotion of tonsillar B cells. rTNF increased the spontaneous polarization and locomotion of unfractionated tonsillar B lymphocytes in a dose-dependent manner by inducing a true chemotactic response. Memory (IgD-, CD38(-)) and naive (IgD+, CD38(-)), but not GC (IgD-, CD38(+)) B cells purified from total tonsillar B lymphocytes, showed a significantly higher locomotion in the presence than in the absence of rTNF. Accordingly, type I and II TNF receptors (TNFRs) were detected by flow cytometry on the surface of memory and naive, but not GC, B lymphocytes. Blocking experiments with monoclonal antibodies to type I or II TNFR showed that rTNF enhanced the spontaneous chemotaxis of memory and naive B cells through the selective engagement of type II TNFR. Finally, the TNF gene was found to be expressed in memory, naive and GC B lymphocytes; the cytokine was released in culture supernatants from the three B-cell subsets after stimulation. These data may support the hypothesis that human TNF is involved in the paracrine and perhaps autocrine control of B-cell migration in secondary lymphoid tissues.

The patterns of IL2, IFN-gamma, IL4 and IL5 gene expression in Hodgkin's disease and reactive lymph nodes are similar

BACKGROUND AND OBJECTIVE

The lymph nodes involved in classic Hodgkin's disease (HD), i.e. mixed cellularity (MC) and nodular sclerosis (NS) subtypes, usually contain few (1-2%) Reed-Sternberg (RS) cells scattered in a background of lymphocytes, eosinophils, plasma cells and neutrophils. CD4+ T-lymphocytes are increased in number, express activation markers and cluster around RS cells. The presence of eosinophilia in most HD patients and the presence of hyper-IgE in a subset of them may suggest that activated lymph node T cells release large amounts of IL5 and IL4, respectively.

METHODS

The expression of four T-cell-associated cytokine genes, i.e. interleukin (IL)2, IL4, IL5 and interferon (IFN)-gamma, in frozen sections of 14 HD (7 MC, 7 NS) and 10 reactive lymph nodes was investigated by qualitative and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). T-cell clones were also raised from purified CD4+ lymphocytes of one HD lymph node and one reactive lymph node and tested for IL2, IL4, IL5 and IFN-gamma secretion in culture supernatants by immunoassays.

RESULTS

The transcripts of all the cytokine genes were detected in every lymph node irrespective of the HD or reactive nature. HD or reactive lymph node-derived CD4+ T-cell clones released the four cytokines according to a predominant T-helper (Th)0-type pattern. In more than half of the lymph nodes of either HD or reactive nature, there was a predominance of IL4 over IFN-gamma mRNA production (Th2-type pattern). In the remaining HD or reactive lymphadenopathies, either a balanced IL4/IFN-gamma mRNA ratio (Th0-type pattern) or a predominance of IFN-gamma over IL4 mRNA expression (Th1-type pattern) was observed.

INTERPRETATION AND CONCLUSIONS

The overall pattern of cytokine gene expression in classic HD is similar to that detected in reactive lymph nodes. Further studies are needed to determine whether differences in the absolute concentrations of cytokines released in HD versus reactive lymph nodes and the long-standing course of HD versus the self-limiting nature of reactive adenopathies may explain certain peculiar features of HD, such as eosinophilia, for example.

Synovial fluid T cell clones from oligoarticular juvenile arthritis patients display a prevalent Th1/Th0-type pattern of cytokine secretion irrespective of immunophenotype

The aim of the present study was to investigate the patterns of cytokine production by T cell clones raised from in vivo activated synovial fluid (SF) mononuclear cells (MNC) of five patients with oligoarticular juvenile arthritis (JA). Freshly isolated SF T cells were cultured in vitro with low dose recombinant IL-2 and subsequently cloned by limiting dilution. Sixty-four clones were obtained from the five patients studied. Fifty-nine clones were TCR alpha/beta+, either CD4+ (n = 43) or CD8+ (n = 15). The remaining five clones were TCR gamma/delta+, CD4-, CD8-. Clone immunophenotypes differed in the individual patients. Forty-four T cell clones were stimulated with phytohaemagglutinin (PHA) and phorbol myristate acetate (PMA) and supernatants tested for the presence of IL-2, IL-4, IL-5 and interferon-gamma (IFN-gamma) by ELISA or bioassays. Cytokine mRNA accumulation was tested by reverse transcriptase-polymerase chain reaction (RT-PCR). Most of 44 clones tested released large amounts of IFN-gamma irrespective of the immunophenotype. Of these, 27 were classified as Th1-type and 17 as Th0-type based upon the IFN-gamma/IL-4 ratio in culture supernatants. Finally, when 10 representative T cell clones were tested for pro- and anti-inflammatory cytokines, gene expression by RT-PCR, all of them were found to express the granulocyte-macrophage colony-stimulating factor (GM-CSF), tumour necrosis factor-alpha (TNF-alpha), IL-10 and transforming growth factor-beta 1 (TGF-beta1) genes, and half of them IL-6 and IL-8 mRNA. In conclusion, T cell clones, that represent the progeny of in vivo activated SF T cells from oligoarticular JA patients, display heterogeneous immunophenotypes, but all share the ability to produce large amounts of IFN-gamma, with a predominant Th1/Th0 pattern. The expression of pro- and anti-inflammatory cytokine genes in these clones suggests that in vivo activated SF T cells modulate joint inflammation in a complex fashion.

Examples of in vivo isotype class switching in IgM+ chronic lymphocytic leukemia B cells

Chronic lymphocytic leukemia (CLL) usually involves the expansion of a clone of CD5+ B cells synthesizing IgM antibodies. These B cells appear to be blocked at the antigen receptor-expressing stage of B cell differentiation and are thought not to undergo an isotype class switch to IgG or IgA production. In vivo and in vitro studies suggest, however, that in some instances terminal differentiation and isotype switching can occur. To test the hypothesis that in vivo isotype class switching occurs in IgM+ B-type CLL cells, we analyzed the PBMC of 19 CLL patients for the presence of transcripts encoding the rearranged CLL V(H)DJ(H) associated with either gamma or alpha H chains. The molecular data indicate that approximately 50% of B-CLL patients have amplifications of IgM+ B cells that undergo an isotype class switch. Switching to IgA appears to occur more often than to IgG; also, switching can involve different IgG subclasses in individual patients. In many instances, these CLL-related gamma and alpha transcripts are much more plentiful than those of normal B cells that produce the same isotype. These switched transcripts do not reveal evidence for the accumulation of significant numbers of new V(H) gene mutations. The cellular data indicate that B cells with lesser amounts of surface membrane IgD and higher IgM/IgD ratios are more likely to undergo this switching process. Furthermore, B cells expressing IgG and IgA of the same idiotype or V(H) family and the same CDR3 length as those of the CLL IgM+ clone can be identified in the blood of patients studied using multiparameter immunofluorescence analyses. Collectively, these data suggest that not all members of a B-CLL clone are frozen at the surface membrane Ig-expressing stage of B cell maturation, and that some members can switch to the production of non-IgM isotypes. The occurrence of switching without the accumulation of V gene mutations indicates that the processes of differentiation and diversification are not linked.

Functional and molecular characterization of tumour-infiltrating lymphocytes and clones thereof from a major-histocompatibility-complex-negative human tumour: neuroblastoma

Neuroblastoma (NB) is a major-histocompatibility-complex(MHC)-negative neuroectodermal tumour that is often infiltrated with lymphocytes. A detailed characterization of NB-associated tumour-infiltrating lymphocytes (TIL) has never been carried out. Here we have investigated the immunophenotype and the cytotoxic activities of TIL from nine and seven NB patients respectively. Furthermore, the T cell receptor (TcR) variability and the patterns of cytokine gene expression of fresh versus recombinant (r) interleukin (IL)-2-cultured TIL were studied in four NB cases. The results obtained showed the following: (1) freshly isolated TIL were comprised of a mixture of CD4+ and CD8+ T cells partially expressing HLA-DR and/or CD25. The CD4/CD8 ratio ranged from 0.5 to 5 in the different cases. Upon culture of TIL with rIL-2, an increased proportion of CD56+ and CD8+ lymphocytes was consistently observed; (2) IL-2-expanded TIL lysed natural-killer(NK)sensitive and lymphokine-activated-killer(LAK)-sensitive target cell lines; (3) reverse-transcriptase/polymerase-chain-reaction (RT-PCR) experiments showed that most TcR V beta genes were expressed both in fresh and in cultured TIL, suggesting that such cell populations were polyclonal; (4) interferon gamma, IL-4, IL-5, tumour necrosis factor (TNF) alpha, IL-8, IL-10 mRNA and, to a lesser extent, IL-2 mRNA were expressed by cultured TIL, as assessed by RT-PCR; the corresponding tumour samples consistently contained TNF alpha, IL-8 and IL-10 mRNA, whereas IL-2 and IFN gamma mRNA were faintly expressed in some NB tumours and IL-4 and IL-5 mRNA were never detected. A total of 90 clones were subsequently raised from IL-2-expanded TIL from six NB patients; 87/90 clones were of T cell lineage with a CD4+ or CD8+ immunophenotype, whereas the 3 remaining clones were of NK cell origin. Upon triggering of the CD3-TcR complex, 64% CD4+ and 77% CD8+ T cell clones killed the murine P815 mastocytoma cell line. Virtually no T cell clone lysed a LAK-sensitive NB cell line whereas 15% CD4+ and 17% CD8+ clones mediated NK-like activity against the K562 cell line. Finally, the patterns of cytokine production by CD4+ clones were roughly consistent with those of a T helper (TH) 1 profile and similar to those observed in CD8+ clones.

On-line urea monitoring: a further step towards adequate dialysis prescription and delivery

The aim of this study is to present a clinical experience carried out with a new device designed to measure on-line Urea Nitrogen concentration in the effluent dialysate. The Biostat 1000 Urea Monitor (Baxter Healthcare, Dirfield, Ill, USA) was utilized in the present study. The monitor is based on the principle that multiple urea measurements in the dialysate effluent from the dialyzer, permit to built a double exponential regression leading to the urea kinetic parameters of the dialysis session. Data obtained with the Urea Monitor were, in the present study, compared with those obtained by direct measurements carried out in blood and dialysate and by the collection of the whole amount of spent dialysate. The monitor provided an accurate value of predialysis BUN without any blood drawing. Urea kinetics were established from multiple dialysate measurements and no blood drawing was necessary. The double pool kinetics were taken into account and Kt/V, PCR and SRI% obtained were comparable to those obtained from direct measurement. Since a projected value of Kt/V can be obtained, the monitor could represent a potential source of information to detect possible filter and machine dysfunction, as well as high rate of recirculation.

Toxoplasma gondii-specific CD4+ T cell clones from healthy, latently infected humans display a Th0 profile of cytokine secretion

Human Toxoplasma gondii (Tg)-specific T cell clones were raised by infecting peripheral blood mononuclear cells (MNC) from two healthy, latently infected individuals with Tg trophozoites. All of the clones had a CD4+ immunophenotype and produced simultaneously interleukin (IL)-2, interferon (IFN)-gamma, IL-4 and IL-5 upon mitogen or antigen stimulation. Tg-specific T cell clones were classified as T helper of type 0 (Th0) since most of them released roughly comparable amounts of IFN-gamma and IL-4. In some clones, a trend to an increased production of IFN-gamma following antigen-specific as compared to non-specific stimulation was observed. The Th0 phenotype was also expressed by T cell clones that had been raised from bulk cultures performed in the presence of IL-4 or IFN-gamma. All of the Tg-specific T cell clones were cytolytic in a non-specific assay which involves the triggering of the CD3-T cell receptor (TcR) complex. Some clones specifically lysed an autologous lymphoblastoid cell line (LCL) that had been infected with Tg trophozoites. Finally, most of the Tg-specific T cell clones produced IL-10, irrespective of whether they had been raised from bulk cultures incubated in the presence or absence of IL-4 or IFN-gamma. Taken together, these findings suggest that Tg-specific Th0 helper cell clones from healthy, latently infected individuals, beside activating toxoplasmacidal mechanisms through IFN-gamma release, might limit the magnitude of the immune response of the parasite by killing Tg-infected antigen-presenting cells and by releasing IL-10.

Analysis of the hepatitis B virus genome and immune response in HBsAg, anti-HBs positive chronic hepatitis

Although the development of antibodies against the hepatitis B virus surface antigen generally leads to the clearance of the infecting virus, anti-HBs reactivity has been reported in patients with chronic hepatitis. In the present study we analyzed the viral genome and the antibody specificity in a series of serum samples collected from a patient who seroconverted to anti-HBs during interferon therapy without clearing HBsAg. The appearance of an anti-HBs response was accompanied by the emergence of a pre-S1 defective viral genome. However, the wild-type adw2 molecular species remained largely dominant during follow up. The patient's antibody response to the surface viral antigens was directed towards the heterologous y subdeterminant and the pre-S1 fragment deleted in the variant hepatitis B virus. These results suggest that the selection of the escape viral mutant does not play a major role in viral persistence.