Modulation of T cell production of interferon-gamma by human monocytes: effect of engagement of CD14 on monocytes

Large-scale monocyte enrichment coupled with a closed culture system for the generation of human dendritic cells

Conventional methods for generating monocyte-derived dendritic cells (DC) for clinical trials utilize the property of plastic adherence to select monocytes from leukapheresis samples. This method is labor-intensive and has the potential for contamination at various steps. We evaluated a large-scale monocyte enrichment procedure using a cell selector (Isolex 300i(R)) followed by culture in a sterile bag system (Stericell(R)) for generation of DC. DC generated in tissue culture flasks after monocyte selection by plastic adherence were compared to those generated in Stericell(R) bags after monocyte enrichment by negative selection with the Isolex(R) 300i. DC were matured with lipopolysaccharide and pulsed with a peptide derived from the melanoma antigen gp100. Peptide-pulsed DC cultured by the two techniques were evaluated for phenotype, viability, ability to induce allogeneic and peptide-specific autologous proliferative responses as well as peptide-specific cytotoxic T-cell responses. The mean monocyte yield from leukapheresis collections was 17+/-2.4%, which increased to 52+/-11% after Isolex(R) selection. The DC yield of plated mononuclear cells from flasks or bags was 2.7+/-0.96% and 4.84+/-2.65%, respectively. DC cultured by both methods expressed high levels of CD86, CD80, CD40, CD83, CD44, CD11c and CD58, and was comparable in their ability to induce allogeneic and peptide-specific autologous proliferative responses as well as gp100 peptide-specific cytotoxic T-cell responses. These results indicate that potent monocyte-derived DC can be generated in a closed culture bag system after monocyte enrichment by immunomagnetic negative selection. Due to the closed nature of the enrichment and culture systems, the potential for contamination is minimized. This protocol is well suited for culturing large numbers of DC for clinical immunotherapy trials.

Regulation of human B cell function by sulfasalazine and its metabolites

Although sulfasalazine is a well-known disease-modifying antirheumatic drug (DMARD), the mechanisms of its action remain unclear. Indeed, it remains uncertain whether sulfasalazine itself or one of its metabolites is responsible for the antirheumatic effects of sulfasalazine. Since one of the characteristic features of rheumatoid arthritis (RA) is chronic stimulation of B cells, we compared the effects of sulfasalazine and its metabolites on the in vitro function of human B cells. Ig production was induced from highly purified B cells from healthy donors by stimulation with Staphylococcus aureus Cowan I (SA) plus IL-2. Sulfasalazine suppressed the production of IgM and IgG at its pharmacologically attainable concentrations (1-10 microg/ml). Of the metabolites of sulfasalazine, sulfapyridine (SP) and 5-aminosalicylic acid (5-ASA), but not 4-acethyl SP, also significantly suppressed the production of IgM and IgG at their pharmacologically relevant concentrations. By contrast, any of sulfasalazine, SP, 5-ASA and 4-acethyl SP did not suppress the IFN-gamma production of immobilized anti-CD3 stimulated CD4+ T cells. These results indicate that sulfasalazine and its metabolites preferentially suppress the function of B cells, but not that of T cells, at their pharmacologically attainable concentrations. The data therefore suggest that not only sulfasalazine, but its metabolites, might contribute to the beneficial effects of sulfasalazine.

Immunological changes in human skeletal muscle and blood after eccentric exercise and multiple biopsies

1. A role of the immune system in muscular adaptation to physical exercise has been suggested but data from controlled human studies are scarce. The present study investigated immunological events in human blood and skeletal muscle by immunohistochemistry and flow cytometry after eccentric cycling exercise and multiple biopsies. 2. Immunohistochemical detection of neutrophil- (CD11b, CD15), macrophage- (CD163), satellite cell- (CD56) and IL-1beta-specific antigens increased similarly in human skeletal muscle after eccentric cycling exercise together with multiple muscle biopsies, or multiple biopsies only. 3. Changes in immunological variables in blood and muscle were related, and monocytes and natural killer (NK) cells appeared to have governing functions over immunological events in human skeletal muscle. 4. Delayed onset muscle soreness, serum creatine kinase activity and C-reactive protein concentration were not related to leukocyte infiltration in human skeletal muscle. 5. Eccentric cycling and/or muscle biopsies did not result in T cell infiltration in human skeletal muscle. Modes of stress other than eccentric cycling should therefore be evaluated as a myositis model in human. 6. Based on results from the present study, and in the light of previously published data, it appears plausible that muscular adaptation to physical exercise occurs without preceding muscle inflammation. Nevertheless, leukocytes seem important for repair, regeneration and adaptation of human skeletal muscle.

Inhibition of human B cell activation by a novel nonsteroidal anti-inflammatory drug, indometacin famesil

Indometacin farnesil (INF) is a prodrug of indomethacin (IND) designed to reduce the occurrence of side-effects by esterification of the carboxyl group on IND with farnesol. Previous studies have shown that INF has the characteristics of disease-modifying anti-rheumatic drug (DMARD) in that it has a component of slow-acting effect in treatment of rheumatoid arthritis (RA), in which abnormal B cell functions are considered to be involved. The current studies therefore examined the effects of INF on human B cells. Ig production was induced from highly purified B cells obtained from healthy donors by stimulation with Staphylococcus aureus Cowan I (SA) plus IL-2. T cell proliferation and IFN-gamma production were induced from highly purified T cells by stimulation with immobilized mAb to CD3. At pharmacologically attainable concentrations, INF, but not IND, suppressed the production of IgM and IgG of B cells, whereas neither suppressed the T cell proliferation and IFN-gamma production. The inhibition of Ig production by INF is not due to its IND structure, but is most likely due to its farnesil component, since farnesol alone comparably suppressed the Ig production. INF and farnesol did not suppress the expression of early activation markers, including CD98, CD25, and CD71, on SA-stimulated B cells, but appeared to inhibit the maturation of B cells following the initial activation. These results indicate that INF preferentially suppresses the human B cell functions. Thus, the data suggest that INF may have more beneficial effects than IND in treatment of RA.

Synergistic inhibition of human B cell activation by gold sodium thiomalate and auranofin

The mechanism of action of gold compounds, which are effective in the treatment of rheumatoid arthritis (RA), has not been clearly identified. Since one of the characteristic features of RA is chronic stimulation of B cells, the current studies compared the effects of parenteral gold (gold sodium thiomalate; GST) and orally active gold (auranofin; AUR) on human B cells. IgM production was induced from highly purified B cells obtained from healthy donors by stimulation with Staphylococcus aureus Cowan I (SA) plus IL-2. T cell proliferation and IFN-gamma production was induced from highly purified T cells by stimulation with immobilized mAb to CD3. AUR as well as GST suppressed B cell IgM production at much lower concentrations than those that suppressed T cell proliferation or IFN-gamma production. Thus, as little as 0.01 microg/ml AUR (0.015 microM) markedly suppressed IgM production, but neither T cell proliferation nor IFN-gamma production. AUR as well as GST is required at the initiation of cultures to exert optimal suppressive effects on IgM production. Moreover, AUR as well as GST suppressed the expression of CD98 and CD71 on SA-stimulated B cells. Of note, AUR and GST exerted a synergistic inhibitory effect on B cell production of IgM and IgG in a manner which was reversed by catalase, but not by ascorbate. The synergistic inhibitory effect is most likely to be due to thiomalate components of GST, since AUR and thiomalate exerted comparable synergistic inhibitory effects on B cell function. Finally, AUR and bucillamine, another antirheumatic drug with thiol groups, also showed synergistic inhibition of B cell function. These results indicate that AUR and GST preferentially inhibit the function of B cells by interfering with the initial activation of B cells. More importantly, the data indicate that AUR synergizes with GST or thiols to inhibit B cell function in a manner that depends upon the generation of hydrogen peroxide. These synergistic inhibitory effects of AUR and compounds with thiols on in vitro human B cell activation suggest the therapeutic efficacy of combinations of these compounds in RA.

Suppressive influences of methotrexate on the generation of CD14(+) monocyte-lineage cells from bone marrow of patients with rheumatoid arthritis

An adequate supply of peripheral blood monocytes, granulocytes, and platelets is necessary for an optimal inflammatory process. We have previously demonstrated that the generation of CD14(+) monocyte lineage cells from the bone marrow is accelerated in patients with rheumatoid arthritis (RA). The current studies examined the influences of methotrexate (MTX), a potent disease modifying antirheumatic drug (DMARD), on the capacity of bone marrow progenitor cells to generate CD14(+) cells in patients with RA, in order to delineate its mechanism of action. CD14(-) cells purified from bone marrow specimens of 14 patients with active RA were cultured in the presence or the absence of pharmacologically attainable concentrations of MTX (0.2 microM). After incubation for 14 days, the cells were analyzed by flow cytometry for expression of CD14 and HLA-DR. The generation of CD14(+) cells from RA bone marrow CD14(-) progenitor cells was significantly suppressed by MTX. However, the expression of HLA-DR on bone marrow-derived CD14(+) cells was not significantly influenced by MTX. There was no significant difference in the effect of MTX on the generation of CD14(+) cells between patients with prednisolone and those without prednisolone. The production of IL-12 in bone marrow cell cultures was not inhibited, but was rather enhanced, by MTX, suggesting that the suppression of the generation of CD14(+) cells might not be due to the inhibition of cytokine production. The results are consistent with the hypothesis that one of the effects of DMARDs may involve the interference with monocyte differentiation in the bone marrow. Moreover, the data suggest that the generation of CD14(+) cells and the expression of HLA-DR on such marrow-derived CD14(+) cells are regulated by different mechanisms.

Human Th1 responses driven by IL-12 are associated with enhanced expression of CD40 ligand

IL- 12 is the prominent inducer of Th1 responses in humans and in the mouse. CD40 ligand (CD40L) plays important roles in regulation of immune responses, including T cell-dependent activation of B cells and cytokine production by monocytes and dendritic cells. The present study examined the influences of IL-12 on the CD40L expression of activated human CD4+ T cells. IL-12 enhanced CD40L expression on CD4+ T cells stimulated with immobilized anti-CD3 in the complete absence of accessory cells, whereas IL-4 and IL-10 decreased it. Exogenous interferon-gamma (IFN-gamma) did not increase CD40L expression on immobilized anti-CD3 stimulated CD4+ T cells at any time up to 168 h of culture. The IL-12-induced enhancement of CD40L expression on anti-CD3 activated CD4+ T cells was not influenced in the presence of a metalloproteinase inhibitor KB8301, which up-regulated CD40L expression by preventing the processing of membrane-bound CD40L, or B cells, which down-regulated CD40L expression by receptor-mediated endocytosis. These results indicate that IL-12 enhances the CD40L expression of activated CD4+ T cells independently of the IFN-gamma production. The data thus suggest that Th1 responses induced by IL-12 might play an important role in the regulation of humoral immune responses through up-regulated CD40L expression.

Differential influences of gold sodium thiomalate and bucillamine on the generation of CD14+ monocyte-lineage cells from bone marrow of rheumatoid arthritis patients

An adequate supply of peripheral blood monocytes, granulocytes, and platelets is necessary for an optimal inflammatory process. We have previously demonstrated that the generation of CD14(+) monocyte-lineage cells from the bone marrow is accelerated in patients with rheumatoid arthritis (RA). The current studies examined the influences of gold sodium thiomalate (GST) and bucillamine (BUC), two potent disease-modifying antirheumatic drugs (DMARDs), on the capacity of bone marrow progenitor cells to generate CD14(+) cells in patients with RA, in order to delineate their mechanisms of action. CD14(-) cells purified from bone marrow specimens of 13 patients with active RA who were not taking DMARDs were cultured in the presence or absence of pharmacologically attainable concentrations of GST (25 microM) or intramolecular disulfide form of bucillamine (BUC-ID, 3 microM), a major metabolite of BUC. After incubation for 14 days, the cells were analyzed by flow cytometry for expression of CD14, HLA-DR, and CD54. The generation of CD14(+) cells from RA bone marrow CD14(-) progenitor cells was significantly suppressed by GST, but not by BUC-ID. The expression of HLA-DR on the bone marrow-derived CD14(+) cells was also significantly inhibited by GST, but not by BUC-ID. Of note, neither GST nor BUC-ID influenced the expression of CD54 on the bone marrow-derived CD14(+) cells, indicating that the expression of HLA-DR and CD54 on the bone marrow-derived CD14(+) cells is regulated by different mechanisms. The results are consistent with the hypothesis that one of the effects of DMARDs may involve the interference with monocyte differentiation in the bone marrow. Moreover, the data emphasize that in contrast with BUC, GST is a potent inhibitor of monopoiesis in RA patients.

Comparative inhibitory effects of bucillamine and D-penicillamine on the function of human B cells and T cells

OBJECTIVE

Clinical trials have suggested that the efficacy of bucillamine (BUC) in rheumatoid arthritis (RA) may be superior to that of D-penicillamine (DP), although the basis of the differences remains unclear. Previous studies have revealed that BUC has unique immunomodulatory effects that depend upon its capacity to form an intramolecular disulfide (BUC-ID). We therefore examined the effects of BUC-ID on the in vitro function of human B cells and T cells compared with those of DP, at their pharmacologically attainable concentrations.

METHODS

IgM production was induced in highly purified B cells from healthy donors by stimulation with Staphylococcus aureus Cowan 1 (SAC) plus interleukin-2 (IL-2) or with immobilized anti-CD3-activated CD4+ T cells. Interferon-gamma (IFN gamma) production was induced in CD4+ T cells by stimulation with immobilized anti-CD3.

RESULTS

BUC-ID suppressed IgM production induced by SAC+IL-2 as well as that induced by immobilized anti-CD3-activated CD4+ T cells, whereas DP suppressed the latter more markedly than the former. DP (3 micrograms/ml) significantly suppressed IFN gamma production by immobilized anti-CD3-stimulated CD4+ T cells, but not IgM production induced by SAC + IL-2 stimulation. By contrast, BUC-ID (0.3 microgram/ml) significantly suppressed IgM production induced by SAC + IL-2, but not T cell IFN gamma production. Of note, BUC-ID did not suppress IL-6 production by SAC-activated B cells.

CONCLUSION

These results indicate that the target cells of BUC and DP in vivo might be different, with the former inhibiting the function of B cells and the latter that of T cells. The data suggest the possibility that BUC may have a different effect in RA patients compared with the effect of DP, and may be effective in patients who do not respond to DP.