Aberrant uterine natural killer (NK)-cell expression and altered placental and serum levels of the NK-cell promoting cytokine interleukin-12 in pre-eclampsia

PROBLEM: Natural killer (NK) cells are the most abundant lymphocyte population at the maternal-fetal interface. They are suggested to be important during placentation by controlling trophoblast invasion. If placentation is suboptimal, pre-eclampsia can occur. METHOD OF STUDY: Decidual NK (dNK) cells were examined at delivery in 46 women, 22 pre-eclamptic women and 24 healthy controls, by staining for CD56 and CD94 with immunohistochemistry (IHC). Furthermore, we investigated the placental expression and the serum levels of the NK-cell activating cytokines interleukin(IL)-12, IL-15, IL-18 and the anti-inflammatory cytokine IL-10 by IHC and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: Pre-eclamptic women had higher number of CD56+ and CD94+ cells in the decidua, indicating an altered receptor expression of dNK cells. We also demonstrate for the first time that the villous trophoblasts show strong immunostaining for IL-12 in placentae from healthy controls, while women suffering from pre-eclampsia have significantly less IL-12. However, pre-eclamptic women had significantly elevated IL-12 and IL-15 levels in serum. CONCLUSION: Results show increased numbers and altered phenotype of dNK cells in pre-eclampsia, supporting the importance of these cells for a healthy pregnancy. The altered receptor expression of dNK cells together with diminished placental IL-12 expression could implicate an altered NK cell-regulation in pre-eclampsia.     

CC chemokines induce the generation of killer cells from CD56+ cells

We describe here that members of the CC chemokines exhibit biological activities other than chemotaxis. Macrophage inflammatory protein (MIP)-1α, MIP-1β, monocyte chemoattractant protein-1 and RANTES, but not interleukin (IL)-8, induce the generation of cytolytic cells, designated here as CHAK (CC chemokine-activated killer) cells to distinguish them from IL-2-activated (LAK) cells. Like IL-2, CC chemokines can induce the proliferation and activation of killer cells. While incubating CC chemokines with CD4⁺ or CD8⁺ cells did not generate CHAK activity, all CC chemokines were capable of inducing CHAK activity upon incubating with CD56⁺ cells, suggesting that the primary effectors are NK cells. However, the presence of other cell types, such as CD4⁺ or CD8⁺, are necessary to induce the proliferation of CD56⁺ cells. Confirming the involvement of T cell-derived factors in inducing the proliferation of these cells, anti-IL-2 and anti-interferon-γ, but not anti-IL-1β, anti-tumor necrosis factor-α, anti-IL-8, or anti-granulocyte/monocyte-colony-stimulating factor inhibited RANTES-induced proliferation of nylon wool column-nonadherent cells. Our results may have important clinical applications for the utilization of CHAK cells in the treatment of cancer and immunodeficient patients.     

CD3+CD56+ NK T cells are significantly decreased in the peripheral blood of patients with psoriasis

Psoriasis is a chronic, inflammatory, hyperproliferative skin disease, in which autoimmunity plays a great role. Natural killer T cells (NK T cells), are suggested to be involved in the pathogenesis of different autoimmune diseases. To examine the involvement of CD3+CD56+ NK T cells in the pathogenesis of psoriasis, we investigated the lymphocyte subpopulations obtained from blood samples of psoriatic patients before and after treatment, and of healthy controls, using two-colour flow cytometry. We found no significant differences between total T cells, total B cells, T helper cells, T cytotoxic cells and NK cells in patients with psoriasis before and after treatment and in controls. Increased percentage of memory T cells and decreased percentage of naive T cells was detected in psoriatic patients compared to controls, but these changes were not statistically significant. The CD3+CD56+ cells of psoriatic patients were significantly decreased relative to controls. The percentage of CD3+CD56+ cells increased after different antipsoriatic therapies, but remained significantly lower than those found in controls. CD3+CD56+ cells of healthy controls were capable of rapid activation, while in psoriatic patients activated NK T cells were almost absent. The decrease in the number of CD3+CD56+ cells may represent an intrinsic characteristic feature of patients with psoriasis, which is supported by the fact that after treatment NK T cells do not reach the values found in controls. In conclusion our results suggest that CD3+CD56+ NK T cells could be actively involved in the development of Th1 mediated autoimmune diseases.     

Uncoupling activation-induced modulation of CD16 and CD69 in CD56+ cells during AIDS

The immune system of HIV+ patients is chronically activated, which has been associated with a detrimental effect on both innate and acquired immunity during AIDS. We analyzed the expression and modulation of the triggering markers CD69 and CD16 in CD56+ cells from 18 asymptomatic HIV+ individuals and 8 AIDS patients, compared with 21 seronegative subjects. We observed a diminished PMA-induced CD16 downregulation in AIDS patients (p<0.01), associated with low numbers of CD4+ cells (p<0.02). Furthermore, an enhanced unstimulated expression of CD69 in asymptomatic HIV+ patients (p<0.05) was shown. AIDS patients could not efficiently upregulate PHA-dependent CD69 expression (p<0.05), which correlated with low CD4+ counts (p< 0.05). These abnormalities in CD16 and CD69 modulation were recorded in patients under highly active antiretroviral therapy (HAART). Our results demonstrate an altered modulation of two functionally relevant receptors in CD56+ cells from AIDS patients, contributing to our understanding of the immunopathogeny of NK cell dysfunction during disease progression.     

Proliferative and cytotoxic capabilities of CD16+CD56- and CD16+/-CD56+ natural killer cells

Natural killer (NK) cells can be divided into several subpopulations according to their expression of the surface antigens CD16 and CD56. The modest quantity of NK cells in the blood available for functional analysis has been a limitation in studies of NK cell subpopulations. In the present study, epinephrine infusion was used to induce lymphocytosis before immunomagnetic methods were applied to isolate CD16+/-CD56+ and CD16+CD56- CD3- NK cells. These subpopulations were compared according to their proliferative and cytotoxic capabilities in 10 human immunodeficiency virus (HIV)-infected individuals and 5 healthy controls. The CD16+CD56- NK cell subgroup had a higher proliferative capacity, whereas the CD16+/-CD56+ NK cell subgroup was mainly cytotoxic, and unaffected by HIV serostatus. This study thus suggests that NK cell phenotypes more strongly predict NK cell function than HIV serostatus. This assertion should be considered when studying NK cell function in subjects with a deviating composition of NK cells.     

Accumulation of CD16-CD56+ natural killer cells with high affinity interleukin 2 receptors in human early pregnancy decidua.

Most human peripheral blood natural killer (NK) cells express the phenotype CD16+CD56+. However, a very minor subset of NK cells express CD16-CD56+, and these NK cells bear both interleukin 2 receptor (IL-2R)alpha (p55) and IL-2R beta (p75) (high affinity IL-2 receptors). In this report, we demonstrate that in human early pregnancy decidua--an interface between maternal immunocompetent cells and fetus (placenta)--abundant (approximately 83%) CD16-CD56+ NK cells with high affinity IL-2 receptors were present, and these cells responded to low amounts of IL-2 (4.5 pM). These CD16-CD56+ NK cells significantly expressed an early activation antigen, CD69, in vivo, whereas peripheral CD16-CD56+ NK cells did not express CD69. These findings suggest that CD16-CD56+ NK cells in early pregnancy decidua may be activated in vivo, and may play an important role in immunoregulation during early pregnancy. Also, decidual lymphocytes may be useful materials to study the mechanism of MHC-unrestricted cytotoxicity of this type of NK cells.     

Aberrant expression of CD95 and CD69 molecules among CD56 cells in women with endometriosis

PROBLEM: Activated lymphocytes can be eliminated by Fas/Fas ligand (FasL)-induced cell death. Endometrial cells express FasL. The aim of our study was to determine the expression of CD56+ cells (natural killer and natural killer T cells) Fas antigen CD95 and the early activation molecule CD69 in the peritoneal fluid of women with endometriosis. METHOD: Two-colour flow cytometry was used. RESULTS: In the early stages of endometriosis, more CD56+ cells expressed CD69 and CD95 molecules when compared with the control group. However, in case of severe endometriosis the percentage of CD95+CD56+ cells in peritoneal fluid was similar to that of the control group, but the expression of CD69 molecules remained high. CONCLUSION: Because of Fas/FasL mechanisms, in the initial stages of endometriosis the activated peritoneal fluid CD56+ cells can be intensively eliminated, thus providing conditions for the survival of ectopic endometrial cells and the development of the disease.     

Simple enumerations of peripheral blood natural killer (CD56+ NK) cells, B cells and T cells have no predictive value in IVF treatment outcome

BACKGROUND: To evaluate the association between the absolute counts of the peripheral natural killer (NK) cells (including total CD56(+) NK cells, CD56(dim) NK cells and CD56(bright) NK cells), B cells and T cells on the implantation rate and miscarriage rate after IVF treatment. METHODS: This was a prospective observation study. A total of 138 patients who underwent IVF treatment from December 2002 to July 2003 were recruited to the study. Blood samples were obtained on the day of vaginal oocyte retrieval prior to the procedure. The absolute counts of lymphocytes, NK cells, B cells and T cells were identified by flow cytometry. These absolute counts and their relationships to IVF treatment outcome and miscarriage rate were analysed. RESULTS: There were no significant differences with regard the mean values of absolute lymphocyte count, T cell count, B cell count and NK cell count (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells) between the pregnant and non-pregnant groups and also between the ongoing pregnancy and miscarriage groups. The cause of infertility, duration of infertility, basal FSH levels, number of previous failed IVF treatments, number of previous miscarriages and stimulation characteristics were not significantly different between the pregnant and non-pregnant groups. Previous studies have suggested that women with a history of recurrent miscarriage and those with infertility accompanied by recurrent failed IVF treatments are associated with a peripheral blood NK cell percentage >12%, therefore further analysis of peripheral CD56(+) NK cell levels <12% (group A) and >12% (group B) was performed. There was no significant difference in implantation rate (group A: 17.0%; group B: 23.2%), pregnancy rate (group A: 36.6%; group B: 47.7%) or miscarriage rate (group A: 23.3%; group B: 28.6%). CONCLUSION: There were no significant differences between simple enumerations of peripheral blood NK cells (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells), B cells and T cells with IVF treatment outcome and pregnancy outcome. Women who had a peripheral NK cell level >12% did not have higher number of previous pregnancy losses. Importantly their pregnancy rate was not reduced and their miscarriages were not increased compared to women who had a peripheral NK cells level <12%.     

Aberrant expression of CD7, CD56, and CD79a antigens in acute myeloid leukemias

The prognostic significance of selected markers of leukemic cells is well known. CD7 and CD56 expression at diagnosis has been associated with low remission rates and biological aggressiveness in a significant proportion of acute leukemias. Among 46 patients with acute myeloid leukemia, we found CD7 expression in 15 cases (32.6%) and CD56 positivity in 10 patients (21.7%). Six of these myeloid leukemia cases (13%) showed expression of both CD7 and CD56. Four of 46 (8.7%) patients expressed CD79a. Among the 10 that were acute myeloblastic leukemia, 8 expressed CD7, 4 expressed CD56, and 4 were positive for CD79a. Thus, these markers were expressed early in hemopoietic ontogeny in the lesser-differentiated acute myeloid leukemia subtypes, including FAB M0, M1, and M2. Whereas CD7 and CD56 were each positive in 4 cases of acute myelomonocytic leukemia (FAB M4 subtype), there was no CD79a expression in the M4 cases. CD7 is expressed by mature T cells, NK cells, and an immature myeloid cell subset. NK cells and a T cell subset express CD56. By contrast, CD79a is a B cell marker that is assigned a high score of 2.0 in the differentiation of acute leukemias of ambiguous lineage in the WHO classification. The aberrant expression of CD7, CD56, and CD79a, representing the capacity of these leukemias for trilineal expression of leukocyte differentiation antigens, portends a poor prognosis.     

Separation methods of T cells, natural killer, and dendritic cells from peripheral blood of cancer patients using interleukin-2 and functional analysis of natural killer cells after separation

We aimed to induce three different immune cell subsets from a single blood sample from cancer patients to target different biological characters of cancer cells. In the presence of 6000 IU/ml IL-2, natural killer (NK) cells adhere to plastic. By using this ability, we could separate dendritic cells, T cells, and NK cells from peripheral blood mononuclear cells. The cultured NK cells demonstrated higher nonspecific cytotoxicity against tumor cell lines than did the T cells. Furthermore, adherent NK cells demonstrated higher cytotoxicity than nonadherent NK cells, although there was no difference between adherent and nonadherent NK cells in natural cytotoxicity receptors (NKp30, NKp44, NKp46) and NKG2D expression. With these results, we confirmed that we could induce dendritic cell, T cell, and higher cytotoxic NK cells from a single blood draw, and this methodology facilitates to the use of these cells for clinical grade conditions.     

CD244抑制活动性肺结核患者CD8+T细胞细胞因子分泌的实验研究

目的 探讨表面受体CD244在活动性肺结核患者CD8+T细胞中的功能.方法 密度梯度离心法提取活动性肺结核患者和健康对照者的外周血单个核细胞,通过流式细胞术检测CD244在CD3+ CD8+细胞中的表达;通过细胞内染色方法检测CD244与细胞因子IFN-γ和TNF-α表达的关系.结果 CD244在活动性肺结核患者CD8+T细胞表达强度显著高于健康对照者(P=0.0003);复治肺结核患者的CD244表达强度显著高于新发肺结核患者(P=0.0011);CD244-细胞表达IFN-γ比例显著高于CD244+细胞(P=0.0013);CD244-细胞表达TNF-α比例显著高于CD244+细胞(P =0.0016).结论 CD244抑制活动性肺结核患者CD8+T细胞的细胞因子分泌表达.     

Interleukin-7 activates p56lck and p59fyn,two tyrosine kinases associated with the p90 interleukin-7 receptor in primary human T cells

We have investigated signaling events associated with the cloned 90-kDa (p90) interleukin-7 receptor (IL-7R) to determine whether changes in the signaling pathways initiated by this molecule can explain the ability of T cells to proliferate to IL-7 following activation. Using in vitro kinase assays we find that the p90 IL-7R in both unstimulated and activated human T cells is physically associated with two molecules with intrinsic kinase activity. Western blotting analysis reveals these proteins to be the src kinase enzymes, p59^fyn and p56^lck. Binding of human recombinant IL-7 to the p90 IL-7R results in increased activity of both receptor-associated kinases in both resting and activated mature T cells. Thus, the signaling pathways initiated via the p90 IL-7R-associated src kinases are unlikely to be solely responsible for the proliferation of only activated T cells in response to IL-7. Additional signals, which may derive from other IL-7R-associated molecules such as the γc, are clearly required for IL-7-driven proliferation of activated primary T cells.     

Pentoxifylline suppresses interleukin-2-mediated activation of immature human natural killer cells by inhibiting endogenous tumor necrosis factor-alpha secretion

We recently reported that immature human peripheral blood-derived natural killer (NK) cells, the free NK subset, can be activated by interleukin-2 (IL-2) to become killer cells and to undergo proliferation. Activation by IL-2 is dependent on endogenous secretion of tumor necrosis factor-alpha (TNF-) by the free cells. Because pentoxifylline (PTX) inhibits TNF- synthesis and secretion in monocytes, we hypothesized that PTX may also inhibit TNF- secretion by NK cells and thus would inhibit IL-2-mediated activation of free cells. The free NK cells were separated from purified NK cells by flow cytometry and cell sorting of non-target binding cells. IL-2-mediated secretion of TNF- by the free cells was inhibited by PTX. In the presence of PTX, IL-2-mediated activation of free cells into cytotoxic function, proliferation, and recruitment of binder and killer cells was markedly inhibited. Also, PTX inhibited IL-2-triggered upregulation of the expression of CD69, CD25, ICAM-1, and p75TNF-R on the cell surface. These findings demonstrate that PTX has a marked suppression on IL-2-mediated activation of immature free NK cells and that the suppression is due, in large part, to PTX-mediated inhibition of endogenous TNF- secretion. The implication of these findings in the clinical use of PTX for therapy is discussed.     

Gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas

BackgroundBreast carcinoma is one of the most common tumors in women. The immune microenvironment, especially T cell infiltration, is related to the occurrence and prognosis of breast carcinoma.ObjectiveThis study investigated the gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas.MethodsThe gene expression data and corresponding clinical phenotype data from the Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) were downloaded. The stromal and immune score were calculated using ESTIMATE. The differentially expressed genes (DEGs) with a high vs. low stromal score and a high vs. low immune score were screened and then functionally enriched. The tumor-infiltrating immune cells were investigated using the Cibersort algorithm, and the CD4+ and CD8+ T cell-related genes were identified using a Spearman correlation test of infiltrating abundance with the DEGs. Moreover, the miRNA-mRNA pairs and lncRNA-miRNA pairs were predicted to construct the competing endogenous RNAs (ceRNA) network. Kaplan-Meier (K-M) survival curves were also plotted.ResultsIn total, 478 DEGs with a high vs. low stromal score and 796 DEGs with a high vs. low immune score were identified. In addition, 39 CD4+ T cell-related genes and 78 CD8+ T cell-related genes were identified; of these, 14 genes were significantly associated with the prognosis of BRCA patients. Moreover, for CD4+ T cell-related genes, the chr22-38_28785274-29006793.1–miR-34a/c-5p–CAPN6 axis was identified from the ceRNA network, whereas the chr22-38_28785274-29006793.1–miR-494-3p–SLC9A7 axis was identified for CD8+ T cell-related genes.ConclusionsThe chr22-38_28785274-29006793.1–miR-34a/c-5p–CAPN6 axis and the chr22-38_28785274-29006793.1–miR-494-3p–SLC9A7 axis might regulate cellular activities associated with CD4+ and CD8+ T cell infiltration, respectively, in BRCA.     

Gene expression analysis of activating and inhibitory receptors of natural killer cells in patients with acute myeloblastic leukemia

PurposeNatural killer (NK) cells are cytotoxic lymphocytes, which have long been known to play an essential role in immune surveillance of tumor cells. The results of several clinical studies imply evidence of impaired activity of NK cells in acute myeloblastic leukemia (AML). The aim of this study was to investigate the gene expression of activating and inhibitory receptors of NK cells in patients with newly diagnosed AML before and after induction therapy using 7 + 3 regimen in comparison to healthy donors.Materials and methodsSixteen AML patients aged 16–64 years as well as 16 matched healthy individuals were studied. Peripheral blood samples from patients were obtained in two steps, namely, in newly diagnosed patients and 28 days after receiving induction therapy. Real-time PCR was performed to evaluate the expression levels of activating receptors, including DNAM-1 and NKp46 as well as inhibitory receptors of KIR2DL1 and NKG2A.ResultsOur results demonstrated that the newly diagnosed patients showed over 50% decrease in NKp46 expression and a 6-fold increase in KIR2DL1 expression compared to healthy controls. The mRNA expression analysis in patients after induction therapy suggested a significant decrease in mRNA expressions of KIR2DL1 and NKG2A in comparison to newly diagnosed patients.ConclusionHerewith, we show a statistical difference in mRNA expression levels of activating (NKp46) and inhibitory receptors from NK cells in newly diagnosed AML patients when compared with healthy controls or patients who received induction therapy, supporting the findings of researchers who reported the impaired NK cells cytotoxicity in AML patients.     

Increased frequency of CD56Bright NK‐cells,CD3−CD16+CD56− NK‐cells and activated CD4+T‐cells or B‐cells in parallel with CD4+CDC25High T‐cells control potentially viremia in blood donors with HCV

A detailed phenotypic analysis of major and minor circulating lymphocyte subsets is described in potential blood donors with markers of hepatitis C virus (HCV), including non‐viremic and viremic groups. Although there were no changes in the hematological profile of either group, increased the levels of pre‐NK cells (CD3^?CD16⁺CD56^?) and a lower frequency of mature NK cells (CD3^?CD16⁺CD56⁺) characterized innate immunity in the non‐viremic group. Both non‐viremic and viremic groups displayed significantly increased levels of CD56^Bright NK cells. Furthermore, this subset was significantly elevated in the viremic subgroup with a low viral load. In addition, an increase in the NKT2 subset was observed only in this subgroup. An enhanced frequency of activated CD4⁺ T‐cells (CD4⁺HLA‐DR⁺) was a characteristic feature of the non‐viremic group, whereas elevated CD19⁺ B‐cells and CD19⁺CD86⁺ cell populations were the major phenotypic features of the viremic group, particularly in individuals with a low viral load. Although CD4⁺CD25^High T‐cells were significantly elevated in both the viremic and non‐viremic groups, it was particularly evident in the viremic low viral load subgroup. A parallel increase in CD4⁺CD25^High T‐cells, pre‐NK, and activated CD4⁺ T‐cells was observed in the non‐viremic group, whereas a parallel increase in CD4⁺CD25^High T‐cells and CD19⁺ B‐cells was characteristic of the low viral load subgroup. These findings suggest that CD56^Bright NK cells, together with pre‐NK cells and activated CD4⁺ T‐cells in combination with CD4⁺CD25^High T‐cells, might play an important role in controlling viremia. Elevated CD56^Bright NK cells, B‐cell responses and a T‐regulated immunological profile appeared to be associated with a low viral load. J. Med. Virol. 81:49–59, 2009. © 2008 Wiley‐Liss, Inc.     

Subtypes of type I IFN differentially enhance cytokine expression by suboptimally stimulated CD4+ T cells

Human type I interferons (IFNs) include IFN‐β and 12 subtypes of IFN‐α. During viral infection, infiltrating memory CD4 ⁺ T cells are exposed to IFNs, but their impact on memory T‐cell function is poorly understood. To address this, we pretreated PBMCs with different IFNs for 16 h before stimulation with Staphylococcus aureus enterotoxin B and measured cytokine expression by flow cytometry. IFN‐α8 and ‐α10 most potently enhanced expression of IFN‐γ, IL‐2, and IL‐4. Potency among the subtypes differed most at doses between 10 and 100 U/mL. While enhancement of IL‐2 and IL‐4 correlated with the time of preincubation with type I IFN, IFN‐γ production was enhanced best when IFN‐α was added immediately preceding or simultaneously with T‐cell stimulation. Comparison of T‐cell responses to multiple doses of Staphylococcus aureus enterotoxin B and to peptide libraries from RSV or CMV demonstrated that IFN‐α best enhanced cytokine expression when CD4 ⁺ T cells were suboptimally stimulated. We conclude that type I IFNs enhance Th1 and Th2 function with dose dependency and subtype specificity, and best when T‐cell stimulation is suboptimal. While type I IFNs may beneficially enhance CD4 ⁺ T‐cell memory responses to vaccines or viral pathogens, they may also enhance the function of resident Th2 cells and exacerbate allergic inflammation.     

Regulation of interleukin-12 receptor β1 chain expression and interleukin-12 binding by human peripheral blood mononuclear cells

The interleukin-12 receptor (IL-12R)β1 chain is an essential component of the functional IL-12R on both human T and natural killer cells. In this report it is shown that activation of human peripheral blood mononuclear cells (PBMC) with anti-CD3 monoclonal antibody (mAb) or phytohemagglutinin resulted in the up-regulation of IL-12Rβ1 expression and IL-12 binding. Kinetic studies revealed that maximum expression of IL-12Rβ1 and IL-12 binding occurred on days 3–4. Anti-CD3-induced expression of IL-12Rβ1 chain and IL-12 binding by PBMC was augmented by anti-CD28 mAb, indicating that the potentiating effect of anti-CD28 on T cell responses to IL-12 could be mediated, at least in part, by the enhancement of IL-12R expression. Among 16 cytokines tested, IL-2, IL-7 and IL-15 markedly induced IL-12Rβ1 expression and IL-12 binding on resting PBMC, whereas IL-1α and tumor necrosis factor-α had a minimal enhancing effect. In contrast, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, interferon (IFN)-α, IFN-γ, granulocyte/macrophage colony-stimulating factor and transforming growth factor (TGF)-β2 had no detectable enhancing effect. Anti-CD3-induced expression of IL-12Rβ1 and of low-affinity IL-12 binding sites was partially inhibited by TGF-β2, IL-10 and IL-4; however, TGF-β2 and IL-10 completely abolished anti-CD3-induced expression of high-affinity IL-12 binding sites. Consistent with the reduction of high affinity IL-12 binding sites, PBMC activated with anti-CD3 mAb in the presence of TGF-β2 or IL-10 failed to produce IFN-γ or to proliferate in response to IL-12. These results suggest that Th2 cell-derived cytokines can inhibit IL-12-induced biological functions by inhibiting IL-12R expression and that expression of a second subunit of the IL-12R (IL-12Rβ2), required for the formation of high-affinity IL-12 binding sites, may be more highly regulated by TGF-β2 and IL-10 than is expression of IL-12Rβ1.