Crk-associated substrate lymphocyte type regulates transforming growth factor-beta signaling by inhibiting Smad6 and Smad7

Crk-associated substrate lymphocyte type (Cas-L) is a 105 kDa docking protein with diverse functional properties, including regulation of cell division, proliferation, migration and adhesion. Cas-L is also involved in beta1 integrin- or antigen receptor-mediated signaling in B and T cells. In the present study, we demonstrate that Cas-L potentiates transforming growth factor-beta (TGF-beta) signaling pathway by interacting with Smad6 and Smad7. Immunoprecipitation experiments reveal that single domain deletion of full-length Cas-L completely abolishes its docking function with Smad6 and Smad7, suggesting that the natural structure of Cas-L is necessary for its association with Smad6 and Smad7. On the other hand, both N-terminal and C-terminal deletion mutants of Smad6 and Smad7 still retain their docking ability to Cas-L, suggesting that Smad6 and Smad7 possess several binding motifs to Cas-L. Moreover, Cas-L interaction with Mad-homology (MH)2 domain, but not with MH1 domain of Smad6 or Smad7, ameliorates TGF-beta-induced signaling pathway. Finally, depletion of Cas-L by small-interfering RNA oligo attenuates TGF-beta-induced growth inhibition of Huh-7 cells, with a concomitant reduction in phosphorylation of Smad2 and Smad3. These results strongly suggest that Cas-L is a potential regulator of TGF-beta signaling pathway.

The tetraspanin CD9 is preferentially expressed on the human CD4(+)CD45RA+ naive T cell population and is involved in T cell activation

Human CD4+ T cells can be divided into reciprocal memory and naive T cell subsets based on their expression of CD45 isoforms and CD29/integrin beta1 subunit. To identify unique cell surface molecules on human T cells, we developed a new monoclonal antibody termed anti5H9. Binding of anti5H9 triggers a co-stimulatory response in human peripheral blood T cells. Retrovirus-mediated expression cloning has revealed that the antigen recognized by anti5H9 is identical to the tetraspanin CD9. We now show that human CD9 is preferentially expressed on the CD4(+)CD45RA+ naive T cell subset, and that CD9(+)CD45RA+ T cells respond preferentially to the recombinant beta2-glycoprotein I, compared to CD9-CD45RA+ T cells. Furthermore, anti5H9 inhibits both the recombinant beta2-glycoprotein I- and the recall antigen tetanus toxoid-specific T cell proliferation. These results suggest that the tetraspanin CD9 plays an important role in T cell activation.

Ebastine inhibits T cell migration, production of Th2-type cytokines and proinflammatory cytokines

BACKGROUND

Cytokine imbalance and cellular migration to inflammatory sites are critical components of allergic diseases. Redirecting cytokine imbalance and inhibiting cell migration therefore represent important therapeutic strategies for the treatment of these disorders.

OBJECTIVES

To study the in vitro effect of ebastine, a novel non-sedating H1 receptor antagonist, on cytokine secretion and migration of activated T cells, as well as production of pro-inflammatory cytokines by macrophages.

METHODS

Peripheral T cells obtained from healthy volunteers were cultured in wells coated with the combination of anti-CD3 monoclonal antibody (mAb) and anti-CD26 mAb, anti-CD3 mAb and anti-CD28 mAb, or anti-CD3 mAb with PMA, in the presence or absence of ebastine. T cell proliferation and the production of cytokines were measured by [3H]thymidine incorporation assay and ELISA, respectively. In addition, transendothelial migration of T cells and production of pro-inflammatory cytokines by macrophages were examined.

RESULTS

Ebastine inhibited T cell proliferation and the production of IL-4, IL-5, IL-6, and TNF-alpha by T cells under each co-stimulatory condition tested, whereas it exhibited no effect on the production of IL-2 or IFN-gamma. In addition, T cell migration and the production of such pro-inflammatory cytokines as TNF-alpha and IL-6 by macrophages were inhibited by ebastine.

CONCLUSIONS

These results indicate that ebastine has a specific inhibitory effect on Th2-type cytokine production. Moreover, ebastine inhibited T cell migration and pro-inflammatory cytokine production by T cells and macrophages, suggesting that ebastine might be useful for the treatment of T cell-mediated allergic inflammatory disorders, including asthma, atopic dermatitis, and Th2-type autoimmune diseases.

Soluble CD26/dipeptidyl peptidase IV induces T cell proliferation through CD86 up-regulation on APCs

CD26 is a T cell costimulatory molecule with dipeptidyl peptidase IV enzyme activity in its extracellular region. We have previously reported that the addition of soluble CD26 (sCD26) resulted in enhanced proliferation of peripheral blood T lymphocytes induced by the recall Ag, tetanus toxoid (TT). However, the mechanism involved in this immune enhancement has not yet been elucidated. In this paper, we demonstrate that the enhancing effect of sCD26 on TT-induced T cell proliferation occurred in the early stages of immune response. The cells directly affected by exogenously added sCD26 are the CD14-positive monocytes in the peripheral blood. Mannose-6 phosphate interfered with the uptake of sCD26 into monocytes, suggesting that mannose-6 phosphate/insulin-like growth factor II receptor plays a role in the transportation of sCD26 into monocytes. When sCD26 was added after Ag presentation had taken place, enhancement in TT-induced T cell proliferation was not observed. In addition, enhancement of TT-mediated T cell proliferation by sCD26 does not result from trimming of the MHC-bound peptide on the surface of monocytes. Importantly, we also showed that exogenously added sCD26 up-regulated the expression of the costimulatory molecule CD86 on monocytes through its dipeptidyl peptidase IV activity, and that this increased expression of CD86 was observed at both protein and mRNA level. Therefore, our findings suggest that sCD26 enhances T cell immune response to recall Ag via its direct effect on APCs.

Recognition of cell surface GD3 by monoclonal antibody anti-6C2 in rheumatoid arthritis synovial fluid: expression on human T cells with transendothelial migratory activity

OBJECTIVE

We have previously reported that the anti-6C2 monoclonal antibody (mAb) defines a subset of human CD4+ memory T cells. The present study sought to determine the nature of the 6C2 molecule and the function associated with 6C2+ T cells, and to examine whether this T cell subset is involved in the pathophysiology of rheumatoid arthritis (RA).

METHODS

Cytofluorographic analysis was performed for identification of T cell surface molecules displaying a distribution similar to that of the 6C2 molecule. T cells in the synovial fluid of RA patients were examined for expression of the 6C2 molecule. Transendothelial migratory activity was assessed by assay using monolayers of human endothelial cells. Specific reactivity of the anti-6C2 mAb was determined by immunoblotting on gangliosides separated by thin-layer chromatography, and flow cytometric analysis of the cells transfected with complementary DNA (cDNA) was performed for determination of the glycosyltransferases involved in biosynthesis of the gangliosides.

RESULTS

On human peripheral T cells, the 6C2 molecule was distributed, by and large, in a pattern similar to that of CDw60, or O-acetyl-GD3. The majority (>70%) of synovial fluid T cells from patients with RA were found to be 6C2 positive, and those 6C2+ T cells exhibited a transendothelial migratory capacity that was inhibited by pretreatment of T cells with anti-6C2 mAb. Moreover, treatment of T cells with neuraminidase resulted in a loss of 6C2 expression as well as a reduction in the transendothelial migratory activity. Anti-6C2 mAb reacted specifically with GD3, but not with O-acetyl-GD3. The reactivity of anti-6C2 mAb was induced on the cell surface only by transfection with cDNA for GD3 synthase.

CONCLUSION

The 6C2 molecule is a disialoganglioside, GD3, and is present on a subset of T cells with transendothelial migratory capacity. The 6C2/GD3 molecules, as well as 6C2/GD3+ T cells, appear to play a role in T cell migration and in the inflammation of RA.

Human herpesvirus type 8 and epstein-barr virus-associated cutaneous lymphoma taking anaplastic large cell morphology in a man with HIV infection

Human herpesvirus type 8 (HHV-8, Kaposi's sarcoma-associated herpesvirus)-positive lymphoma taking anaplastic large cell morphology in the skin is described in a 46-year-old man with AIDS. Multiple erythematous nodules appeared on the trunk and extremities during the treatment of AIDS. Histological examination of cutaneous nodules showed dense infiltration of CD30 + atypical lymphoid cells in the deep dermis. Immunoglobulin JH gene rearrangement was detected in these lymphoma cells. Both Epstein-Barr virus-encoded small RNA and HHV-8 mRNA (T1.1/nut-1) were detected in these lymphoma cells by in situ hybridization. Remarkable retention of the pericardial fluid was observed at the same time that cutaneous lesions grew, and lymphoma cells in the pericardial fluid showed the same phenotype as the cutaneous lymphoma. Chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone effectively reduced both the cutaneous nodules and pericardial fluid. However, the patient died 4 months after diagnosis because of cytomegalovirus infection. As far as we know, this is the first report of an HHV-8-positive cutaneous lymphoma taking anaplastic large cell morphology. This case suggests the association of AIDS-related anaplastic large cell lymphoma with HHV-8.

Decreased dipeptidyl peptidase IV enzyme activity of plasma soluble CD26 and its inverse correlation with HIV-1 RNA in HIV-1 infected individuals

Human plasma contains soluble CD26/dipeptidyl peptidase IV (sCD26/DPPIV) although its physiological significance remains unclear. To determine whether the plasma sCD26 levels have clinical relevance in HIV-1 infected individuals, the concentration and DPPIV enzyme activity of plasma sCD26 were measured. While there is no significant difference between the plasma levels of sCD26 in 90 HIV-1 infected individuals and in 79 uninfected controls, specific DPPIV enzyme activity of sCD26 was significantly decreased HIV-1 infected individuals (P < 0.0001). Specific DPPIV enzyme activity was correlated with the levels of CD4+ T cells (r = 0.247; P < 0.02), CD8+ T cells (r = 0.236; P < 0.03), and adenosine deaminase (r = 0.227; P < 0.05) and had an inverse correlation with HIV-1 RNA (Spearman's r = 0.474; P = 0.0012). Furthermore, recombinant sCD26 enhanced the in vitro PPD-induced response of lymphocytes from HIV-1 infected individuals with decreased specific DPPIV enzyme activity. These results suggest that the specific DPPIV enzyme activity of plasma sCD26 may contribute to the immunopathogenesis of HIV infection.

Human T lymphocyte populations which bind to P- or E-selectin are enriched with cells expressing core 2 O-glycans

The present study was undertaken to investigate whether core 2 O-glycans are involved in binding of resting human T lymphocytes to P- or E-selectin and in recruitment of these cells to inflammatory sites. Freshly isolated human peripheral blood T lymphocytes were incubated with P- or E-selectin-coated dishes, and expression of core 2 O-glycans by the adherent and nonadherent cells was examined using the anti-1D4 mAb, which specifically recognizes human CD43 modified with core 2 O-glycans. The results indicated that both the P-selectin/adherent and E-selectin/adherent populations were significantly enriched with ID4+ cells, as compared with the initial population. An enrichment of ID4+ cells in the P- and E-selectin/adherent populations was observed in both CD4 and CD8 T cell subsets and even in the CD45RO+ memory CD4 T-cell subset. However, the anti-1D4 mAb did not inhibit binding of human T lymphocytes to P- or E-selectin, indicating that the 1D4 antigen itself is not directly involved in selectin binding. We also found that the percentage of ID4+ cells in synovial fluid T lymphocytes of rheumatoid arthritis patients was significantly increased as compared with normal peripheral blood T lymphocytes. Taken together, our results support the notion that core 2 O-glycans, which are located apart from the ID4 antigen, are involved in binding of human resting T lymphocytes to both P- and E-selectin, and these interactions may contribute to preferential recruitment of human memory CD4 T lymphocytes to inflammatory sites, including the synovium of rheumatoid arthritis patients.

CD26/dipeptidyl peptidase IV differentially regulates the chemotaxis of T cells and monocytes toward RANTES: possible mechanism for the switch from innate to acquired immune response

CD26, a 110 kDa cell surface glycoprotein, exhibits dipeptidyl peptidase IV (DPPIV; EC 3.4.14.5) enzyme activity and plays an important role in T cell co-stimulation. In the present study, the function of CD26/DPPIV in transendothelial migration was examined using beta-chemokines as chemoattractants. When soluble recombinant CD26 (sCD26/DPPIV+) was added to the transendothelial chemotaxis system, chemotactic migration of T cells toward RANTES was significantly enhanced. Addition of sCD26 to 50 ng/ml of RANTES enhanced the migratory response by a factor of two compared to RANTES alone, whereas mutant soluble CD26 (mCD26), lacking the DPPIV enzyme activity, had no enhancing effect on RANTES-induced T cell migration. In the process of analyzing the mechanisms of the enhancement of T cell migration by sCD26, we showed that RANTES was cleaved by sCD26 under physiologic conditions at the precise site characteristic of its enzyme specificity. However, synthesized RANTES which lacks two N-terminal amino acids showed a chemotactic activity equivalent to full-length RANTES on T cells. Furthermore, addition of sCD26 showed enhancement of T cell migration induced by both forms of RANTES. In contrast to T cells, the truncated RANTES is inactive in chemotaxis of purified monocytes and supplement of sCD26 but not mCD26 reduced the migratory response of monocytes to RANTES. These results suggest that CD26/DPPIV differentially regulate the chemotactic response of T cells and monocytes to RANTES.

Core 2-containing O-glycans on CD43 are preferentially expressed in the memory subset of human CD4 T cells

Human CD4 T cells can be divided into two functionally distinct subsets: a CD45RO+ memory subset and a CD45RA+ naive subset. In an attempt to identify novel cell surface molecules on these cells, we have developed a mAb, anti-1D4. The antigen defined by anti-1D4 was preferentially expressed on the memory subset of freshly isolated peripheral CD4 T cells and 1D4+ CD4 T cells functionally corresponded to memory T cells. Retrovirus-mediated expression cloning revealed that the 1 D4 antigen is human CD43. Transfection of CHO-leu cells, which stably express human CD43, with core 2 beta-1,6-N-acetylglucosaminyltransferase (C2GnT) conferred expression of the 1D4 antigen and mRNA of C2GnT was detected by RT-PCR only in 1D4+ T cells but not in 1D4- T cells, implying that the 1 D4 antigen is composed of core 2-containing O-glycans on CD43. Reactivity with anti-1 D4 was completely abolished when cells were treated with neuraminidase, while them remained weak binding of anti-T305, a previously described mAb which also reacts with CD43 modified with core 2-containing O-glycans. Moreover, anti-1D4 markedly reacted with NIH-3T3 cells expressing human CD43 and low levels of endogenous C2GnT, whereas anti-T305 reacted slightly. These results indicate that the 1D4 antigen is distinct from the epitope defined by anti-T305 and anti-1D4 is a more sensitive probe to detect core 2-containing O-glycans than anti-T305. Taken together, our results indicate that core 2-containing O-glycans, whose expression can easily be detected with anti-1D4, are preferentially expressed in the CD45RO+ memory subset of CD4 T cells.

Negative regulation of the anti-human immunodeficiency virus and chemotactic activity of human stromal cell-derived factor 1alpha by CD26/dipeptidyl peptidase IV

Stromal cell-derived factor 1alpha (SDF-1alpha) is a chemokine that has been shown to prevent infection of T-tropic HIV strains and is a possible substrate of CD26/dipeptidyl peptidase IV (DPPIV). In this study, we show that SDF-1alpha was cleaved at the N-terminal region by CD26/DPPIV and as a result the inhibitory activity of SDF-1alpha against HIV infection disappeared. Moreover, the chemotactic activity of SDF-1alpha also disappeared specifically by DPPIV activity of recombinant soluble CD26. These results suggested that dissemination of T-tropic HIV strains in vivo may be facilitated by CD26/DPPIV via inactivation of functional SDF-1alpha.

Cytomegalovirus (CMV) retinitis and CMV antigenemia as a clue to impaired adrenocortical function in patients with AIDS

OBJECTIVE

To elucidate the relationship between the activity of CMV disease and adrenocortical function in patients with AIDS.

DESIGN AND PATIENTS

CMV retinitis and CMV antigenemia assay (CMV-Ag: numbers of polymorphonuclear leukocytes positive for CMV pp65 antigen per 1.5 x 10(5) cells) are the least invasive and easily accessible examinations to assess the CMV disease activity. All HIV-infected patients with CD4+ lymphocyte counts < 50 x 10(6)/l who were admitted to the Research Hospital of the Institute of the Medical Science (University of Tokyo) between May 1995 to April 1996 were included in this study.

METHODS

Fundoscopic examination on CMV retinitis and CMV-Ag were chosen as methods to assess CMV activity because of their simplicity. Adrenocortical function was evaluated by basal plasma adrenocorticotropin, plasma cortisol, plasma aldosterone, plasma renin activity, and responses of plasma cortisol and plasma aldosterone to 250 micrograms intravenous cosyntropin [rapid adrenocorticotropin test (RAT)].

RESULTS

Thirty patients were enrolled in this study with a maximum CD4+ lymphocyte count of 32 x 10(6)/l. Eleven out of 30 patients showed impaired RAT response (37%). Fourteen out of 30 patients had CMV retinitis. A significant correlation was found between the presence of CMV retinitis and subnormal cortisol response (P < 0.005). Sixteen out of the 30 patients were CMV-Ag-positive. A significant correlation was found between CMV-Ag positivity and subnormal cortisol response to RAT (P < 0.005). CMV-Ag levels in the patients with subnormal cortisol response to RAT were significantly higher than those with normal response (P < 0.001). Importantly, five patients with subnormal cortisol response but not overt adrenal insufficiency at the time of RAT developed overt disease shortly afterwards. Autopsy was performed in six patients with subnormal cortisol response and showed multiple inclusion bodies indicative of CMV adrenitis.

CONCLUSION

The adrenal gland is most frequently affected by CMV in AIDS patients. Our result suggests that CMV retinitis or CMV-Ag positivity independently serve as an indication of possible adrenal dysfunction.

[Clinical significance of anti-cardiolipin antibody in patients with systemic lupus erythematosus (SLE)]

Anti-cardiolipin antibody (aCL) in SLE patients reacts with cardiolipin/beta 2-GP1 complex. In order to disclose clinical significance of aCL in patients with SLE, aCL was determined by newly-developed anti-CL.beta 2-GP1 kit [Yamasa] EIA in 58 patients with SLE and the relationship between clinical manifestation of SLE and the presence of aCL was examined. Anti-cardiolipin antibody was positive in 20 patients (34.5%). In 20 SLE patients with positive aCL, livedo reticularis in 7, retinal vein thrombosis in 3, thrombophlebitis in 3 and other vasculo-occlusive episodes were observed as a characteristic clinical features of positive aCL. In contrast, a SLE patient complicated by ileal perforation due to necrotizing angiitis had negative aCL. Other clinical and laboratory features associated with aCL include recurrent fetal loss and thrombocytopenia.

Integrin VLA-5 negative primary plasma cell leukemia

We present a case of primary plasma cell leukemia with Bence Jones proteinuria. After combination chemotherapy, leukemic cells and the urinary levels Bence Jones protein were decreased. Small lytic bone lesions were detected only in the skull. Typical plasma cells were rarely seen in peripheral blood on the hyperleukocytic phase, however they were increased in the advanced stages. The most important diagnostic sign was persistent expression of CD38 antigen on leukemic cells throughout the entire course of the illness and these leukemic cells expressed very late antigen-4 (VLA-4) but not VLA-5.

Differentiation of human lambda I variable regions with a monoclonal antibody to a defined, germ-line-encoded idiotope correlates with V lambda Ia chemical structure

This article describes the characterization of a mouse monoclonal anti-idiotypic antibody (1H7B) prepared against a human monoclonal rheumatoid factor (RFSJ2) whose L chain utilized a V lambda I subgroup gene. The mAb 1H7B reacted with 6 of the tested 12 human V lambda I proteins, as well as with a newly produced lambda mAb whose V lambda gene usage has not as yet been determined. Because six of the 1H7B-positive mAb were heterogeneous with respect to both their VH gene utilization and antigenic specificity, and because mAb 1H7B did not react with any of the tested 43 kappa or 12 lambda proteins belonging to various subgroups other than V lambda I, mAb 1H7B appeared to be a V lambda I subgroup-specific reagent. The L chain specificity of mAb 1H7B was confirmed by Western blotting, and the inhibition of RFSJ2 binding to human Fc gamma by 1H7B provided additional evidence for the V region specificity of mAb 1H7B. The 11 sequenced V lambda I proteins used in this study were assigned to sub-subgroups by comparison with the previously published germ-line V lambda Ia, V lambda Ib, and V lambda Ic sequences. The mAb 1H7B only appeared to recognize V lambda Ia proteins as it reacted with five of the seven V lambda Ia, but not with three V lambda Ib or with one V lambda Ic protein. Because mAb 1H7B reacted with at least one V lambda Ia sequence in germ-line configuration, it appeared to be a marker for V lambda Ia sub-subgroup germ-line gene(s). The idiotope recognized by 1H7B was localized to the first framework region by inhibiting its binding to RFSJ2 with a synthetic peptide to the 11-24 amino acid region of V lambda Ia L chains. Comparison of the V lambda 1-24 region sequence of RFSJ2 with those of the two 1H7B-negative V lambda Ia mAb revealed a single amino acid difference at position 17, suggesting that the idiotope recognized by 1H7B encompassed this position.

Differentiation of human lambda I variable regions with a monoclonal antibody to a defined, germ-line-encoded idiotope correlates with V lambda Ia chemical structure

This article describes the characterization of a mouse monoclonal anti-idiotypic antibody (1H7B) prepared against a human monoclonal rheumatoid factor (RFSJ2) whose L chain utilized a V lambda I subgroup gene. The mAb 1H7B reacted with 6 of the tested 12 human V lambda I proteins, as well as with a newly produced lambda mAb whose V lambda gene usage has not as yet been determined. Because six of the 1H7B-positive mAb were heterogeneous with respect to both their VH gene utilization and antigenic specificity, and because mAb 1H7B did not react with any of the tested 43 kappa or 12 lambda proteins belonging to various subgroups other than V lambda I, mAb 1H7B appeared to be a V lambda I subgroup-specific reagent. The L chain specificity of mAb 1H7B was confirmed by Western blotting, and the inhibition of RFSJ2 binding to human Fc gamma by 1H7B provided additional evidence for the V region specificity of mAb 1H7B. The 11 sequenced V lambda I proteins used in this study were assigned to sub-subgroups by comparison with the previously published germ-line V lambda Ia, V lambda Ib, and V lambda Ic sequences. The mAb 1H7B only appeared to recognize V lambda Ia proteins as it reacted with five of the seven V lambda Ia, but not with three V lambda Ib or with one V lambda Ic protein. Because mAb 1H7B reacted with at least one V lambda Ia sequence in germ-line configuration, it appeared to be a marker for V lambda Ia sub-subgroup germ-line gene(s). The idiotope recognized by 1H7B was localized to the first framework region by inhibiting its binding to RFSJ2 with a synthetic peptide to the 11-24 amino acid region of V lambda Ia L chains. Comparison of the V lambda 1-24 region sequence of RFSJ2 with those of the two 1H7B-negative V lambda Ia mAb revealed a single amino acid difference at position 17, suggesting that the idiotope recognized by 1H7B encompassed this position.

The presence of anti-protein A antibodies in patients with rheumatoid arthritis

Sixteen patients with rheumatoid arthritis (RA) were examined for the presence of anti-protein A antibodies. The F(ab')2 preparations from five RA patients showed significant binding to IgG-free protein A on ELISA. The protein A binding was further examined by immunoblotting. The F(ab')2 preparations of high protein A-binding protein gave a specific reaction with IgG-free protein A on nitrocellulose paper. This demonstrates the presence of anti-protein A antibodies in patients with RA. Those RA patients with anti-protein A antibodies had more active disease as judged by the Lansbury's activity index. The level of serum rheumatoid factor (RAHA) was significantly higher in patients with anti-protein A antibodies than in those without anti-protein A antibodies.

Thrombotic thrombocytopenic purpura in two patients with systemic lupus erythematosus: clinical significance of anti-platelet antibodies

Thrombotic thrombocytopenic purpura (TTP) is a clinical syndrome of unknown etiology and has a high mortality rate due to disseminated platelet thrombi. However, the mechanism of platelet agglutination is not understood. Although an immunological mechanism has been suggested as the basis for the pathogenesis of TTP, any possible immune-mediated etiology remains unclear. The association of TTP with systemic lupus erythematosus (SLE) affords a unique opportunity to study such possibilities, because SLE is a prototype of autoimmune disease. This report describes two patients with SLE who developed TTP. The development of anti-platelet antibodies is one possible immunological mechanism for platelet agglutination in patients with SLE complicated by TTP. More importantly, patient J.Y., who had anti-platelet antibodies, responded dramatically to high doses of prednisolone.

CCA [N-(2-carboxyphenyl)-4-chloroanthranilic acid disodium salt], a newly developed immunomodulating drug, suppresses T-cell activation by acting on macrophages

The cellular mechanism of action of a newly developed drug, CCA, N-(2-carboxyphenyl)-4-chloroanthranilic acid disodium salt, on PHA-, autologous mixed lymphocyte reaction (AMLR)-, and phorbol myristate acetate (PMA)-stimulated T-cell proliferation was investigated. Addition of 50 micrograms of CCA per milliliter suppressed PHA- and AMLR-stimulated T-cell proliferation. In contrast, CCA failed to suppress PMA-stimulated macrophage-depleted T-cell proliferation. After treatment of T cells or macrophages with CCA for 12 h, recombined T cells and macrophages were stimulated with phytohemagglutinin. [3H]Thymidine incorporation by T cells was suppressed when macrophages but not T cells were treated with CCA. These results indicate that CCA suppresses T-cell proliferation by acting on macrophages. The mechanism involved in this suppression of CCA was due to the loss of Ia antigen on macrophages and the loss of interleukin-1 (IL-1) secretion from macrophages.

Suppression of in vitro production of anti-U1-ribonucleoprotein antibody by monoclonal anti-idiotypic antibody to anti-U1-ribonucleoprotein antibody

We produced monoclonal anti-idiotypic antibody against immunoaffinity purified anti-U1-ribonucleoprotein (RNP) antibody from a patient (K.T.), by the cell fusion procedure. The specificity of monoclonal anti-idiotypic antibody (IgG1, kappa) was determined by inhibition studies. With the monoclonal anti-idiotypic antibody, cross-reactive idiotypes on anti-U1-RNP antibodies from unrelated patients with anti-U1-RNP antibody was detected in 57% of the samples. The anti-idiotypic antibody specifically suppressed the in vitro production of anti-U1-RNP antibody by lymphocytes from the patient K.T., and unrelated patients with a cross-reactive idiotype, in whom idiotype-reactive T cells were demonstrated. The results indicate that anti-idiotypic antibody may modulate the regulation of in vitro anti-U1-RNP antibody production.

Cellular regulation of anti-nRNP antibody synthesis is different from that of anti-DNA antibody synthesis in patients with systemic lupus erythematosus

The cellular regulation of anti-nuclear ribonucleoprotein (nRNP) antibody synthesis in patients with systemic lupus erythematosus (SLE) was examined and compared with that of anti-double-stranded DNA (dsDNA) antibodies. In vitro antibody production by lymphocytes from SLE patients with antibodies to either dsDNA or nRNP alone was measured using dsDNA-specific and nRNP-specific solid-phase radioimmunoassays (RIA). Lymphocytes of SLE patients with only anti-dsDNA antibodies and normal individuals failed to synthesize anti-nRNP antibody with or without nRNP stimulation. In contrast, lymphocytes from SLE patients with anti-nRNP antibody alone in their sera synthesized in vitro a large amount of anti-nRNP antibody with or without nRNP stimulation. Experiments with reconstituted autologous lymphocytes indicated that B cells and T cells were required for anti-nRNP antibody synthesis. As expected, helper function for antibody synthesis by autologous B cells resided in the T4-cell population and suppressor function in the T8-cell population. T8 cells from SLE patients with anti-nRNP antibody alone suppressed anti-nRNP antibody synthesis by autologous B cells irrespective of clinical activity. This is in contrast to anti-dsDNA antibody production, which was not suppressed by autologous T8 cells. These results indicate that the cellular regulation of anti-nRNP antibody synthesis in SLE is different from that of anti-dsDNA antibody synthesis. Increased anti-nRNP antibody synthesis may be due to increased T4-helper cell function rather than defective T8-suppressor function.

Defects of autologous mixed lymphocyte reaction-activated immunoregulatory T cells in patients with systemic lupus erythematosus

The present study was undertaken to determine the nature of the immunoregulatory T-cell defect after autologous mixed lymphocyte reaction (AMLR) activation in patients with systemic lupus erythematosus (SLE). Although AMLR was decreased in patients with SLE compared with normals, there was no difference in major proliferative cells (T4 cells and T4+JRA+ subset) in response to AMLR. Functional activity of AMLR-stimulated T4 subsets in patients with SLE and normals was examined in helper and suppressor/inducer assay, using pokeweed mitogen (PWM)-driven IgG synthesis. The T4+JRA- (helper) subset from SLE patients showed no greater activity than normals. However the T4+JRA+ (suppressor/inducer) subset from SLE patients showed decreased suppression induction compared with normals. This defect in the suppressor/inducer function was demonstrated even in patients with inactive SLR or in remission.

DNA-daunorubicin complexes specifically suppress in vitro spontaneous anti-DNA antibody production in lymphocytes of patients with systemic lupus erythematosus

Elevated production of anti-DNA antibody in patients with systemic lupus erythematosus (SLE) is a central problem in the pathogenesis of tissue injury. In the present study, we attempted to manipulate anti-DNA antibody production through the antigen-cytotoxic drug conjugates, DNA-daunorubicin complexes. The effect of DNA-daunorubicin complexes was determined by examining SLE lymphocytes for spontaneous in vitro production of anti-DNA antibody. These complexes, at 2 micrograms/ml, suppressed anti-DNA antibody production, but not total IgG production, which suggests that specific suppression of anti-DNA antibody production was achieved at this concentration. We believe that the DNA-daunorubicin complexes affected mainly B cells, since such suppression was obtained by treating B cells, as well as B plus T cells. Furthermore, the complexes had no effect on the proliferative responses of SLE T cells to DNA, phytohemagglutinin, or concanavalin A. These results indicate that DNA-daunorubicin complexes may have the potential for selectively suppressing anti-DNA antibody production in patients with SLE.

Direct demonstration of immunoregulatory T-cell defects in patients with systemic lupus erythematosus

The present study was undertaken to determine directly whether immunoregulatory T cells have a defective suppressor function in patients with systemic lupus erythematosus (SLE), and whether anti-T-cell antibodies are essential for immunoregulatory T-cell defects. Peripheral blood T cells and T-cell subsets were determined in 52 SLE patients. The ratio of T4 to T8 cells was distributed over a wider range in patients with SLE than in the controls. Patients with SLE were divided into three groups (low, normal and high) by the T4/T8 ratio. Lymphocytes from 12 SLE patients (7 with low and 5 with high T4/T8 ratios) were studied extensively. Their disease was inactive or in remission. Anti-T-cell antibodies were not detected, and yet the patients had immunological abnormalities characterized by the presence of antinuclear antibodies and hypergammaglobulinaemia. The SLE patients with high T4/T8 ratios had a decreased number of T8 cells, and defective suppressor-effector cells. In contrast, patients with low T4/T8 ratios had decreased T4 cells and/or increased T8 cells, and defective suppressor-inducer cells. Two patients with low T4/T8 ratios had both suppressor-effector and suppressor-inducer cell defects. These results indicate that immunoregulatory circuits in SLE patients are heterogeneous and that immunoregulatory defects exist even when the disease is inactive or in remission. Anti-T-cell antibodies were not essential for such immunoregulatory defects. Thus, immunoregulatory T-cell defects and the development of SLE may be independent conditions due to other unknown causes.

[Comparative studies on immunological property of thyroglobulins obtained from the thyroid tumor and the adjacent tissue]

The immunological properties of thyroglobulins (Tg) of individual patients, obtained from a thyroid tumor and its adjacent tissue were compared, using conventional or monoclonal antibodies against human Tg. The thyroid tumors studied were non-functioning thyroid carcinomas and functioning thyroid adenomas. In contrast to non-functioning tumors, Tg from the functioning tumors was generally iodinated at a level close to that of normal tissue, and Tg from the tissue adjacent to the tumors had a very low iodine content. The conventional antiserum and monoclonal antibodies, B2F, seemed to recognize the conformation of Tg, while C6G showed a high affinity to Tg even when unfolded or denatured. In most cases, Tg isolated from the tissue adjacent to a tumor showed a higher affinity to antibodies than Tgs of the tumor tissue, as determined by the inhibitional effect of these Tgs against the binding of standard Tg and antibody. Furthermore, the Tg of the adjacent tissue was immunologically different in nature from the standard Tg obtained from a normal thyroid gland. From these results, Tgs of tumor and the adjacent tissue in individual patients were heterogeneous in immunological property, regardless of iodine content.

Suppression of rheumatoid factor synthesis by antiidiotypic antibody in rheumatoid arthritis patients with cross-reactive idiotypes

The effect of antiidiotypic antibody on the in vitro production of rheumatoid factor was studied in rheumatoid arthritis patients with cross-reactive idiotypic determinants. Antiidiotypic antibodies (ascites IgG) were developed against monoclonal rheumatoid factor (Ka m-RF) by a cell fusion procedure. These antibodies were idiotype-specific, since: 1) they reacted only with F(ab')2 fragment of Ka m-RF; 2) they failed to react with normal IgM without rheumatoid factor activity; and 3) their F(ab')2 fragment inhibited the rheumatoid factor activity of Ka m-RF. The antiidiotypic antibody strongly suppressed the in vitro production of rheumatoid factor by lymphocytes from unrelated rheumatoid arthritis patients with cross-reactive idiotypes. The suppression was specific, since ascites IgG failed to suppress in vitro anti-keyhole limpet hemocyanin antibody production by the lymphocytes. These results indicate that antiidiotypic antibody may influence the regulation of rheumatoid factor production in patients with rheumatoid arthritis.

[The immunochemical properties of thyroglobulin in human thyroid tumors in reaction to rabbit anti-human normal thyroglobulin-serum]

Interactions between antiserum (rabbit anti-human normal thyroglobulin-serum) and human thyroglobulin preparations (obtained from the tissues of the normal thyroid gland, thyroid adenoma, and carcinoma) were compared by inhibition effect with the binding between 131I-labeled standard thyroglobulin and antiserum, set up by a double antibody RIA. Thyroglobulins isolated from normal glands (designated as Nor-Tg) have a high affinity to the antiserum. In contrast, thyroglobulins in follicular adenoma or adenomatous goiter (designated as Ad-Tg) decrease the potency of the affinity to the antiserum. Furthermore, thyroglobulins in papillary or follicular carcinoma (designated as Ca-Tg) markedly decrease such a potency. With the t-test, the inhibition curves of Nor-Tgs are almost parallel to each other. Most of the inhibition curves of Ad-Tgs and Ca-Tgs are not parallel to the curve of Nor-Tg 1 (P-value for non-parallelism less than or equal to 0.05). Therefore, it seems that Tg preparations obtained from tumor tissue are heterogeneous in terms of specificity and/or affinity to antiserum, judging from the results of the non-parallel inhibition curves. The present results also show that the contribution of iodine content in Tg has little or no effect on the nature of Tg-immunogenicity.

Cellular mechanism of DNA-specific antibody synthesis by lymphocytes from systemic lupus erythematosus patients

The cellular mechanism of anti-DNA antibody synthesis in patients with systemic lupus erythematosus (SLE) was studied by DNA-specific solid-phase radioimmunoassay. Anti-DNA antibody synthesis in response to DNA was T-dependent, and the experiments with reconstituted lymphocytes from identical twins discordant for SLE showed that B cells and T cells from SLE patients must cooperate to synthesize anti-DNA antibody. Anti-DNA antibody synthesis by lymphocytes from patients with inactive SLE was enhanced by T4 cells and suppressed by T8 cells in response to DNA. Although T4 cells from patients with active SLE could enhance anti-DNA antibody synthesis by autologous B cells, their T8 cells could not suppress anti-DNA antibody synthesis by autologous B cells. These results indicate that elevated anti-DNA antibody synthesis in response to DNA in patients with active SLE is due to abnormalities of both SLE B cells and SLE T cells. They further indicate that dysfunction of T8 cells from patients with active SLE may, in part, be responsible for deficient regulation of anti-DNA antibody synthesis.

Suppressor T cell function in patients with rheumatoid arthritis complicated by vasculitis

Concanavalin A (Con A)-induced suppressor T cell activity was determined in 10 rheumatoid arthritis (RA) patients with vasculitis, 34 RA patients without vasculitis, and 10 healthy individuals. The percent Con A-induced suppression in RA patients with vasculitis was 24.6. In contrast, it was 68.4% in those RA patients without vascular lesions. Further, the proportion of T cells reactive with OKT8 monoclonal antibody was also decreased in RA patients with vasculitis. Accordingly, the reduced Con A-induced suppressor T cell activity in these RA patients resulted, in part, from the reduction in the number of cells of the suppressor T cell subset. Those patients with vascular lesions also had a higher percentage of positive antilymphocytotoxic antibodies than RA patients without vasculitis. Since the differences in Con A-induced suppressor T cell activity and frequency of positive antilymphocytotoxic antibodies were so great, we believe RA patients with vasculitis could be recognized as a disease group distinct from RA patients without vasculitis.

Anti-idiotypic antibodies in a patient with monoclonal rheumatoid factor after pneumococcal bacteremia

A 51-yr-old Japanese female patient with monoclonal IgM gammopathy with rheumatoid factor activity was admitted because of pneumococcal bacteremia. About 2 wk after admission, her rheumatoid factor activity became undetectable by RAHA test and radioimmunoassay, subsequent to the initial marked elevation. The suppressive capacity of the patient's IgG fraction on the rheumatoid activity of her monoclonal IgM on January 11 was determined. The IgG fraction obtained on February 22 blocked the binding of the rheumatoid factor to rabbit IgG. The suppressive activity in the IgG fraction of February 22 was shown to be localized within the F(ab')2 fragment. Furthermore, the specificity of the suppressive serum factor was shown by the inability to block the binding of SRBC coupled with diazotized phosphorylcholine to anti-pneumococcal antibody. Thus, the marked reduction of rheumatoid factor activity was considered to result from anti-idiotypic antibody transiently appearing in her serum after pneumococcal bacteremia.

Anti-idiotypic antibodies in a patient with monoclonal rheumatoid factor after pneumococcal bacteremia

A 51-yr-old Japanese female patient with monoclonal IgM gammopathy with rheumatoid factor activity was admitted because of pneumococcal bacteremia. About 2 wk after admission, her rheumatoid factor activity became undetectable by RAHA test and radioimmunoassay, subsequent to the initial marked elevation. The suppressive capacity of the patient's IgG fraction on the rheumatoid activity of her monoclonal IgM on January 11 was determined. The IgG fraction obtained on February 22 blocked the binding of the rheumatoid factor to rabbit IgG. The suppressive activity in the IgG fraction of February 22 was shown to be localized within the F(ab')2 fragment. Furthermore, the specificity of the suppressive serum factor was shown by the inability to block the binding of SRBC coupled with diazotized phosphorylcholine to anti-pneumococcal antibody. Thus, the marked reduction of rheumatoid factor activity was considered to result from anti-idiotypic antibody transiently appearing in her serum after pneumococcal bacteremia.