The progesterone receptor antagonist mifepristone does not lower serum progesterone induced blocking factor (PIBF) in the presence of progesterone.

PURPOSE: To determine if mifepristone can lower serum levels of a progesterone (P) induced immunomodulatory protein believed to be needed for the fetus to escape immune surveillance. MATERIALS AND METHODS: A female volunteer had her serum P induced blocking factor (PIBF) increased by ingestion of oral micronized P. While remaining on P mifepristone, 200 mg/day was given for six days when another serum PIBF level was obtained. RESULTS: The serum PIBF was 273 ng/ml after five days of oral micronized P. It increased further to 737 ng/ml despite taking six days of 200 mg mifepristone. CONCLUSIONS: The mechanism for inducing abortion by mifepristone does not seem to be related to decreasing serum levels of PIBF. This does not eliminate the possibility that the mechanism involves reducing the intracytoplasmic PIBF levels.

Sunitinib mediates reversal of myeloid-derived suppressor cell accumulation in renal cell carcinoma patients.

PURPOSE: Immune dysfunction reported in renal cell carcinoma (RCC) patients may contribute to tumor progression. Myeloid-derived suppressor cells (MDSC) represent one mechanism by which tumors induce T-cell suppression. Several factors pivotal to the accumulation of MDSC are targeted by the tyrosine kinase inhibitor, sunitinib. The effect of sunitinib on MDSC-mediated immunosuppression in RCC patients has been investigated. EXPERIMENTAL DESIGN: Patient peripheral blood levels of MDSC and regulatory T-cell (Treg) and T-cell production of IFN-gamma were evaluated before and after sunitinib treatment. Correlations between MDSC and Treg normalization as well as T-cell production of IFN-gamma were examined. The in vitro effect of sunitinib on patient MDSC was evaluated. RESULTS: Metastatic RCC patients had elevated levels of CD33(+)HLA-DR(-) and CD15(+)CD14(-) MDSC, and these were partially overlapping populations. Treatment with sunitinib resulted in significant reduction in MDSC measured by several criteria. Sunitinib-mediated reduction in MDSC was correlated with reversal of type 1 T-cell suppression, an effect that could be reproduced by the depletion of MDSC in vitro. MDSC reduction in response to sunitinib correlated with a reversal of CD3(+)CD4(+)CD25(hi)Foxp3(+) Treg cell elevation. No correlation existed between a change in tumor burden and a change in MDSC, Treg, or T-cell production of IFN-gamma. In vitro addition of sunitinib reduced MDSC viability and suppressive effect when used at >/=1.0 microg/mL. Sunitinib did not induce MDSC maturation in vitro. CONCLUSIONS: Sunitinib-based therapy has the potential to modulate antitumor immunity by reversing MDSC-mediated tumor-induced immunosuppression.

Suppressive effects of cyclosporine A on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant ulcerative colitis.

An intravenous infusion of cyclosporine A (CsA) shows clinical benefits in patients with steroid-resistant ulcerative colitis (UC). To clarify its mechanisms, we investigated the ability of CsA to inhibit the functions of neutrophils and T cells. The cytotoxic activity by mucosal T cells was analyzed by anti-CD3-triggered cytotoxicity after lamina propria mononuclear cells were cultured with recombinant interleukin (IL)-2. The chemotactic response, the generation of superoxide, and the production of chemokines, IL-8, and macrophage inflammatory protein-1alpha by neutrophils were examined using a multiple-well chamber assay, a chemiluminescence method, and an enzyme-linked immunosorbent assay (ELISA), respectively. Mucosal chemokine activity was determined by an ELISA using the organ culture supernatant of mucosal biopsy tissues. Pretreatment with CsA caused consistent inhibitions of cytotoxic activity by mucosal T cells and chemotactic migration, superoxide generation, and chemokine production by neutrophils mostly in a dose-dependent manner. In patients who received an intravenous infusion of CsA, mucosal chemokine activity decreased after therapy in parallel with decreases in the numbers of neutrophils and mononuclear cells in the biopsy tissues. These results suggest that suppressive effects of CsA on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant UC.

Production and characterization of a monoclonal antibody specific for ubiquitin-like polypeptide responsible for nonspecific immune suppression.

Monoclonal nonspecific suppressor factor (MNSF) is a lymphokine product of a murine T cell hybridoma that inhibits the immune response in an antigen nonspecific manner. Recently, we found that a novel ubiquitin-like protein (Ubi-L), a subunit of MNSF, is responsible for its biological activity. We developed a monoclonal antibody with specific activity against Ubi-L. Inhibition experiments showed that this mAb, termed NA4, preferentially recognizes Ubi-L but not irrelevant proteins such as ubiquitin. With the use of NA4, we established an ELISA method for the quantitation of Ubi-L. By this ELISA system, approximately 40 ng/ml of MNSF was detected in the culture supernatants of concanavalin A (Con A)- or interferon gamma (IFN gamma)-activated splenocytes, whereas MNSF in the supernatant of IFN alpha- and IFN beta-stimulated splenocytes was nil. In addition, NA4 could abrogate the action of Ubi-L. Thus NA4 was confirmed to be a pertinent tool for elucidation of the underlying mechanism of action of MNSF.

Tumor necrosis factor antibody treatment of septic baboons reduces the production of sustained T-cell suppressive factors.

Post-traumatic septic complications result from impaired cell-mediated immune function, which is caused in part by circulating T-cell suppressive factors (TSFs). We examined whether tumor necrosis factor alpha (TNF-alpha) antibody treatment in a baboon sepsis model influences the production of TSFs, including interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta). Sepsis was induced in anesthetized baboons by Escherichia coli infusion, and caused an increase in plasma levels of TNF, TSF activity, IL-10, and active TGF-beta, as well as a decrease in latent TGF-beta. TNF antibody pretreatment reduced TNF levels by 98%. Transient TSF activity (0-4 h) was only marginally influenced, while sustained TSF activity (8-24 h) was markedly reduced. TSF activity at 24 h correlated with peak TNF levels. IL-10 levels, coinciding with early TSF activity, remained unchanged by anti-TNF treatment. Levels of active TGF-beta and the drop in latent TGF-beta were decreased. We conclude that anti-TNF treatment reduces sustained TSF activity and may partially restore impaired cell-mediated immune function.

Induction of serum-borne immunomodulatory factors in B6C3F1 mice by carbon tetrachloride. I. Carbon tetrachloride-induced suppression of helper T-lymphocyte function is mediated by a serum borne factor.

Following carbon tetrachloride-induced liver injury, hepatotrophic factors are synthesized and released into the serum to facilitate the regeneration of damaged hepatic tissue. We investigated the possibility that immunosuppression could be mediated through induction of a serum factor(s) because in vivo exposure of B6C3F1 mice to carbon tetrachloride selectively inhibits T-cell-dependent immune responses. Addition of mouse serum (5% by volume) obtained from mice treated with carbon tetrachloride (250 or 500 mg/kg/day for 7 days) to naive spleen cell cultures markedly suppressed the sheep red blood cell antibody-forming cell response compared to controls (P < 0.01). Immunosuppression was observed in mice sensitized with sheep red blood cells 48 h, but not 24 or 72 h, following one dose of carbon tetrachloride (1000 mg/kg). Only serum isolated from mice 48 h following exposure to a single dose of carbon tetrachloride (1000 mg/kg) suppressed the antibody-forming cell response when added in vitro to spleen cell cultures. Biodistribution studies using [14C]-labelled carbon tetrachloride demonstrated that accumulation of the [14C]-label was primarily associated with excretory organs (liver, kidneys and lungs) but not with the serum, red blood cells, or spleen. Surprisingly, 24 and 48 h following exposure to [14C]-labelled carbon tetrachloride, an increase in radioactivity was detected in the thymus. The distinct profile of immunosuppressive activity associated with serum isolated from carbon tetrachloride-treated mice and the biodistribution studies clearly demonstrating a negligible amount of carbon tetrachloride or metabolites in the serum strongly implicate the role of a carbon tetrachloride-induced serum borne immunosuppressive factor.

[The significance of a natural inhibitory factor in the pathogenesis of disseminated sclerosis]. / Znachenie estestvennogo ingibiruiushchego faktora v patogeneze rasseiannogo skleroza.

Results indicate that during exacerbation patients with multiple sclerosis showed marked T-lymphopenia, decrease of histamine-sensitive RFC while active RFC exhibited varied changes of their content; increase of the circulating immune complexes, absence or low NIF level. The effect of corticosteroid therapy on the NIF dynamics was evaluated and its level was found to be increased due to hormone treatment. Prednisolone furthers T-cell immunodeficiency and also reduces the intensity of autoimmune reactions in multiple sclerosis. NIF may be used as a prognostic criterion for the evaluation of completeness and duration of the remission. Prolonged functioning of NIF leads to suppression of the patient's immune reactivity requiring immunocorrection.

L-5-hydroxytryptophan stimulated cortisol escape from dexamethasone suppression in melancholic patients.

The dexamethasone suppression test (DST) was carried out in 62 depressed patients. At 0800 the postdexamethasone cortisol values were determined and 125 mg L-5-hydroxytryptophan (L-5-HTP) was administered. The second cortisol sample at 0930 revealed a significant enhancing effect for L-5-HTP on the postdexamethasone cortisol values in melancholic patients, whereas no effects were detected in minor depressives. Our results show that L-5-HTP converts some DST suppressors into nonsuppressors, whereas the escape from dexamethasone in some nonsuppressors is markedly stimulated. The L-5-HTP-stimulated 0930 postdexamethasone cortisol values performed markedly better than the 0800 DST results: at a cut-off value of greater than or equal to 5 micrograms/dl the sensitivity for melancholia increased from 46% to 68%, and the specificity remained unchanged (96%).