Pattern Of Cytokine Production Research Articles

In Vitro Secretion of Cytokines by Human Bone Marrow: Effects of Age and Estrogen Status1

It has been proposed that cytokines mediate the acceleration of bone loss following menopause. Because of the intimate relationship between bone marrow stromal cells and bone tissue, it is possible that marrow cells and their products contribute to the bone microenvironment and influence the regulation of bone cell differentiation and activity. We examined the production of cytokines by bone marrow stromal cells from a total of 37 women and 15 men undergoing total hip replacement for noninflammatory joint disease. Low-density mononuclear cells were isolated from bone marrow and were cultured in phenol red-free alpha MEM medium supplemented with 10% FBS and antibiotics. Constitutive secretion of interleukin-6 (IL-6) was positively correlated with age in a series of 8 women and 5 men measured by bioassay (r = 0.98; P < 0.01) and in a series of 18 women and 10 men measured by immunoassay (r = 0.56; P < 0.01). The pattern of cytokine production by bone marrow stromal cells was examined in detail in 23 postmenopausal women, aged 49-88 yr. Basal secretion of immunoreactive IL-6 and IL-11, but not granulocyte-macrophage colony-stimulating factor, increased with time in culture. Exogenous IL-1 beta stimulated secretion of IL-6 and IL-11 in a saturable, dose-dependent manner. Secretion of soluble IL-6 receptor was not correlated with secretion of IL-6, either constitutively or in the presence of IL-1 beta. In 4 of 14 samples, IL-1 beta also stimulated secretion of granulocyte-macrophage colony-stimulating factor. IL-1 beta was undetectable in 7 of 9 cultures during the 2-week culture period. IL-6 did not stimulate secretion of IL-1 beta in the 7 cultures tested. Cells were dependent upon serum for viability and growth and were not sustained by a serum substitute (1% insulin-transferrin-selenium-BSA). Cells grown in medium with 10% FBS and supplemented with 1% insulin-transferrin-selenium-BSA secreted 10-fold more IL-6 than cells grown in serum alone. Marrow from 7 women receiving estrogen replacement therapy showed lower constitutive secretion of IL-6 (75%; P < 0.006) and IL-11 (43%; P < 0.05) than marrow from age-matched controls and had blunted stimulation of IL-6 and IL-11 secretion by exogenous IL-1 beta. These data indicate distinct patterns of cytokine production by human marrow stromal cultures dependent upon age and estrogen status.

CD30 EXPRESSION IDENTIFIES A NOVEL ALLOREACTIVE T CELL SUBSET THAT IS FOUND WITHIN REJECTING ALLOGRAFTS

100 Alloantigenic stimulation leads to the development of T cell subsets with immunoregulatory and effector function. The purpose of this study was to identify and characterize novel T cell subsets that participate in alloreactivity through the production of cytokines. On day 3 of human MLR we noted the development of a population of CD45R0+lymphocytes that express the CD30 antigen. Immunofluorescence and flow cytometry indicated that a significant proportion of CD4 (16.2±2.3%) and CD8 T cells(19.3±3.0%) express CD30 in response to alloantigen. Within the CD4 subset, CD30 cell reside in the CD4hi fraction. CD30 cells also express CD25 and CD28. However, CD30 is not a general marker of alloactivation since CD25+CD30- cells also arise in MLR. Fluorescence activated cell sorting was used to determine the functional properties of CD30 T cells. Purified alloactivated CD30+, CD30-, and unsorted alloactivated cells were restimulated with alloantigen or anti-CD3 mAbs for 48 h and cytokine production determined by ELISA. CD30+ cells produced significantly more IFN-γ (6.2 ng/ml) and IL-5 (5.5 ng/ml) than did the CD30- population (0.6 ng/ml and 2.1 ng/ml, respectively). however, CD30+ and CD30- cells produced comparable amounts of IL-10 (1.1 ng/ml and 1.9 ng/ml, respectively) when restimulated with anti-CD3 mAbs. Similar patterns of cytokine production were noted when cells were restimulated with alloantigen. An agonist anti-CD30 mAb (M44) synergized with anti-CD3 mAbs and led to enhanced production of IL-5 and IFN-γ but not IL-2. To examine the role of CD30 cells in allograft rejection we utilized the DA to Lewis orthotopic liver transplant model in which rejection typically occurs on day 12-14. Total RNA obtained from allograft tissue on days 2, 4, and 8 post-transplant were analyzed by RT-PCR for CD30 transcripts. CD30 mRNA could be detected as early as day 2 post-transplant and increased in intensity through day 8. Lewis to Lewis isografts did not contain CD30 mRNA. To determine if CD30 cells were found within the inflammatory infiltrate, liver infiltrating mononuclear cells (LIMC) were isolated from day 4 allografts and RT-PCR was performed. A prominent band corresponding to CD30 transcripts was evident in LIMC. To confirm the amplified sequence was derived from rat CD30 the PCR product was cloned into the pT-Adv vector and sequenced. Sequence analysis indicated that the molecule was 97.6% homologous with the previously published rat CD30 sequence. Taken together, these data indicate that CD30 acts as a signaling molecule in alloactivated T cells. Furthermore, CD30+ T lymphocytes may constitute a novel immunoregulatory population that participates in allograft rejection through the production of cytokines.

Oral Delivery of Homologous and Heterologous Strains of Rotavirus to BALB/c Mice Induces the Same Profile of Cytokine Production by Spleen Cells

In this work, we wanted to clarify if differences in antibody (Ab) and particularly in secretory immunoglobulin A (IgA) responses following homologous or heterologous rotavirus infection could be explained by different priming of specific T helper (Th) cells. We compared the Ab responses from suckling BALB/c mice orally inoculated with either a heterologous simian (SA11) or bovine (RF) rotavirus or a homologous murine rotavirus (EHPw), as well as the profile of cytokines produced by spleen cells afterin vitrorestimulation. Oral inoculation of EHPwand SA11 induced a similar pattern of Ab with mucosal and serum IgA associated with serum IgG with equal levels of IgG1 and IgG2a, whereas RF elicited a weak humoral response. We found that these strains induced the same mixed Th1/Th2 pattern of cytokine production by spleen cells with IFN-γ and IL-5 as well as IL-10, but not IL-2 or IL-4. These findings suggest that the induction of immune response is probably not different between these strains. Other factors such as the amount of antigen, strain immunogenicity, and other cytokines, particularly produced in effector sites, remain to be considered in order to better explain the differences in secretory IgA following homologous or heterologous rotavirus infection.

Immunization of mice with phosphatidylcholine drastically reduces the parasitaemia of subsequent Plasmodium chabaudi chabaudi blood-stage infections.

It has been suggested that phospholipids and antibodies directed against phospholipids are important in the pathology of malaria. We have investigated the influence of immunizations with phospholipids on the course of subsequent blood-stage Plasmodium chabaudi chabaudi infections in ICR inbred mice. We observed a significant reduction in the parasitaemia following immunization with phosphatidylcholine (PC), but not with phosphatidylethanolamine (PE) immunization. At the peak of the infection, PC-immunized mice displayed a T-helper 2 (Th2)-type cytokine production pattern, whereas PE-immunized or non-treated controls displayed a cytokine production pattern of the T-helper 1 (Th1) type. Serum immunoglobulin transfer from PC-immunized mice protected naive mice in a similar fashion to PC-immunization, demonstrating that the observed reduction of parasitaemia was caused by the presence of PC-specific antibodies.

Immunocytochemical detection of cytokines and chemokines in Langerhans cells and in vitro derived dendritic cells

We have developed a direct immunocytochemical technique to identify cytokine and chemokine production in epidermal Langerhans cells (LC) and in vitro derived CD14−, CD1a+, CD83+, CD40+ dendritic cells (DC) at the single cell level. Formaldehyde fixation combined with saponin permeabilization preserved cellular morphology and generated a characteristic juxtanuclear staining signal due to the accumulation of cytokine to the Golgi organelle. This approach was used for the assessment of TNF- α, IL-6, IL-8, IL-10, IL-12, GM-CSF, MIP-1 α, MIP-1 β and RANTES producing cells. In contrast, a diffuse cytoplasmic staining was evident for IL-1ra, IL-1 α and IL-1 β production. IL-1ra and IL-1 α were expressed in 10–25% of unstimulated cultured cells, while all the other cytokines were undetectable. IL-1ra, IL-1 α and IL-1 β were also the dominating cytokines, expressed in up to 85% of the DC, after 3 h of LPS stimulation. A significantly lower number of cells (0–5%) synthesized TNF- α, IL-6, IL-10, IL-12 and GM-CSF. The incidence of chemokine producing cells (IL-8, RANTES, MIP-1 α, MIP-1 β) peaked 10 h after LPS stimulation in up to 60% of the DC. Both immature CD83− and mature CD83+ DC as well as LC had a similar cytokine production pattern. Thus, in comparison to monocytes, LPS stimulation of DC generated a lower incidence of TNF- α, IL-6, IL-10 and IL-12 producing cells while IL-1 was expressed in a comparable number of cells.

Different pattern of cytokine production and mRNA expression by lymphoid and non-lymphoid cells isolated from human palatine tonsil.

To investigate the cytokines involved in the interaction between circulating (B and T lymphocytes) and non-circulating (stromal cells) elements present in lymphoid tissue, highly purified populations were isolated from human tonsils and the cytokine production and mRNA expression (interleukin-1 alpha, -2, -4, -5, -6, -8, -10, leukocyte inhibitory factor, granulocyte-macrophage colony-stimulating factor, and interferon-gamma) were assessed both by immunoassay and reverse transcriptase polymerase chain reaction under resting conditions and after activation with tumor necrosis factor-alpha. Under basal conditions most cytokines were not detected, except for interleukin-8 which was produced by T lymphocytes and lymphoid cells. Activation by tumor necrosis factor-alpha induced interleukin-8 production by B lymphocytes. Tonsillar T lymphocytes expressed mRNA for interleukin-1 alpha, -8, -10, -4, leukocyte inhibitory factor, and interferon-gamma, only interleukin-4 was expressed by resting peripheral blood T lymphocytes. Tonsillar B lymphocytes were mRNA positive for interleukin-1 alpha, -8, -10, leukocyte inhibitory factor, and interferon-gamma, these were not expressed by peripheral blood B lymphocytes. Stromal cells constitutively produce interleukin-6 whose levels increased 5 times upon tumor necrosis factor-alpha activation Granulocyte-macrophage colony-stimulating factor and interleukin-8 were detected only after tumor necrosis factor-alpha activation. Only stromal cells constitutively express interleukin-6 and granulocyte-macrophage colony-stimulating factor and show a cytokine pattern different from that described for other non-lymphoid cells, such as follicular dendritic cells. These data indicate that in the human tonsil population, lymphoid and non-lymphoid cells can be distinguished by different patterns of cytokine expression.

Kinetics of cytokine and NFAT gene expression in human interleukin-2-dependent T lymphoblasts stimulated via T-cell receptor.

T cells respond to mitogenic or antigenic stimulation by proliferation and by turning on cytokine gene expression. Here we have analysed the kinetics and nature of cytokine production in human peripheral blood-derived T lymphoblasts stimulated with anti-CD3 antibodies or Lens culinaris lectin (LCL). T cells were purified from peripheral blood mononuclear cells (PBMC) and primarily activated with anti-CD3 antibodies and cultured in the presence of interleukin-2 (IL-2). Anti-CD3-restimulated T cells (mainly CD8+) produced IL-2, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) and low levels of IL-4 and IL-10 transcripts and proteins. No IL-6 gene expression was observed. In LCL-stimulated cells the cytokine production pattern was very similar. Steady-state mRNA levels of IL-2, IL-10 and IFN-gamma peaked at 3 hr after anti-CD3 stimulation and declined rapidly thereafter. The kinetics of TNF-alpha mRNA expression was faster, being at its peak level 1 hr after stimulation. Anti-CD3-stimulated IL-2 gene expression was down-regulated by protein synthesis inhibitor, whereas IL-10, IFN-gamma and TNF-alpha genes were readily induced independent of ongoing protein synthesis. T-cell receptor stimulation also induced a very rapid expression of c-jun, c-fos and NFATc1 (NFATc) genes, the gene products of which are involved in cytokine gene expression. In conclusion, the cytokines synthesized by IL-2-dependent T cells were predominantly IL-2, IFN-gamma and TNF-alpha.

Long-Lived Th2 Clones Specific for Seasonal and Perennial Allergens Can Be Detected in Blood and Skin by Their TCR-Hypervariable Regions

We investigated the longevity of allergen-specific Th cells derived from patients suffering from either allergic rhinitis or atopic dermatitis. T cell clones (TCC) specific for seasonal and perennial allergens were raised. To determine whether these TCC were long-lived in vivo, PBMC and allergen-specific polyclonal T cell lines, collected and established inside a period of up to 4 years, were screened for the TCC of interest. For this purpose, a T cell tracing protocol was established in which oligonucleotides specific for the TCR beta-chain hypervariable junctional region were used as tools to identify each particular TCC. Seven pollen-specific TCC and two house dust mite-specific TCC, with a Th2-like cytokine production pattern in vitro, were demonstrated to be long-lived memory T cells in vivo. Specificity of the tracing protocol was ascertained by TCR sequence analysis. We conclude that allergen-specific TCC can persist for years, evidence for which can be monitored in blood, but also in the target organ of the allergic disorder. The data indicate that in vitro-characterized, allergen-specific, long-lived TCC may well reflect a repertoire of T lymphocytes of pathogenetic importance in vivo.

Administration to mouse of endotoxin from gram-negative bacteria leads to activation and apoptosis of T lymphocytes.

Lipopolysaccharide (LPS) from gramnegative bacteria is a well-known T cell-independent B lymphocyte mitogen and macrophage/monocyte activator. While the conventional view holds that LPS is ignored by T cells, we report here that administration of LPS to mice activates all B cells, but also engages most CD4 and CD8 T cells, as measured by the expression of the activation markers CD69 and CD25 and by size increase. T cells recruited in endotoxin-treated mice showed, following in vitro stimulation by concanavalin A, altered patterns of cytokine production. In vivo, massive T cell apoptosis was evidenced in the days following LPS exposure. The present observation may contribute novel insights into the mechanisms of endotoxin shock and of the immunological consequences of gram-negative infections.

Disease Specific Patterns of Cytokine Production by T-Lymphocytes in Coronary Atherosclerosis: Evidence for a Role of Infectious Agents in the Pathogenesis of Unstable Angina?

Disease Specific Patterns of Cytokine Production by T-Lymphocytes in Coronary Atherosclerosis: Evidence for a Role of Infectious Agents in the Pathogenesis of Unstable Angina?

Altered pattern of cytokine production by peripheral blood CD2+ cells from B chronic lymphocytic leukemia patients.

To determine if activation-induced cytokine production is altered in CD2+ lymphocytes from B-CLL patients, cytokine levels were determined by ELISA in supernatants of PHA-stimulated cultures of CD2+ cells from 33 B-CLL patients and 22 healthy controls. The production of Interferon gamma (IFN-gamma) and Tumor Necrosis Factor (TNF-alpha) by mitogen-activated CD2+ lymphocytes from B-CLL patients was higher than that found in healthy controls, while no differences were found in TNF-beta production. IFN-gamma and TNF-alpha levels determined at 72 h in PHA-stimulated CD2+ cell cultures from B-CLL patients statistically correlated with the percentages of CD3+CD45RO+ and CD3-CD56+ lymphocytes, respectively. Although there were differences in the production kinetics of interleukins (ILs) 2 and 4 between B-CLL patients and the healthy controls, no differences were found at the time when the levels of both interleukins peak. The production of both IFN-gamma and IL-4 by PHA-stimulated CD2+ lymphocytes from non-smouldering B-CLL patients was significantly higher than that from smouldering B-CLL patients while no significant differences were found in the production of IL-2, TNF-alpha, and TNF-beta between the two B-CLL patient groups. These data suggest that functional alterations in the production of cytokines by CD2+ cells from B-CLL patients could help to explain the expansion of leukemic cells in B-CLL patients.

Advances in the Immunogenetics of Coeliac Disease. Clues for Understanding the Pathogenesis and Disease Heterogeneity

Recent studies using the technique of the human genome screening in families with multiple siblings suffering from coeliac disease have suggested the presence of at least four different chromosomes in the predisposition to suffer from coeliac disease. Two loci in chromosome 6 appear to be important in disease susceptibility. Other studies based on cytokine gene polymorphisms have found a strong association with a particular haplotype in the TNF locus. This haplotype carries a gene for a high secretor phenotype of TNF !. The finding may be important in understanding the heterogeneity of inflammatory response. Evidence has been presented in favour of a predominantly Th1 pattern of cytokine production by the coeliac disease associated HLA-DQ restricted T cell clones. HLA-DQ2 and -DQ8 restricted gliadin-specific T cells have been shown to produce IFN- n , which appears to be an indispensable cytokine in the damage to enterocytes encountered in the small intestine, since the histological changes can be blocked by anti-IFN- n antibodies in vitro. TNF- α , also produced by several T cell clones, may in conjunction with IFN- n have a toxic effect or enhance the IFN- n -induced increase of HLA-class II expression on surface enterocytes. In the lamina propria this leads to an increased expression of adhesion molecules such as ICAM-1 on T lymphocytes and macrophages. Th1 cells also activate cytotoxic CD8+ T cells that migrate in the epithelial layer, and stimulate further LPL macrophages to produce IFN- n and TNF- α enhancing the inflammatory response. During this process autoreactive T cells proliferate, creating a situation which is very similar to the process that takes place in autoimmune diseases. Occasionally, this inflammatory destruction of the small intestinal integrity initiated by gluten peptides goes further and develops into a proper autoimmune disease which requires the use of immunosuppressive drugs in addition to a gluten-free diet.

Antiviral cell-mediated immune responses during hepatitis B and hepatitis C virus infections.

Cell-mediated immune responses to hepatitis B (HBV) and hepatitis C virus (HCV) antigens are vigorous and multispecific in acute, self-limited infections. Moreover, the prevalent cytokine pattern of circulating virus-specific T cells from patients who recover spontaneously from acute hepatitis is Th1-like. Longitudinal analysis of the T cell response to HCV antigens from the early stages of HCV infection in patients who recover from hepatitis and those who do not indicates that weaker responses and a prevalent Th2 pattern of cytokine production is associated with viral persistence and chronic evolution of disease. Although similar sequential studies are missing in hepatitis B, the observation that HBV-specific T cell responses are very weak or totally undetectable in the peripheral blood of patients with long-lasting chronic hepatitis B suggests that strength and quality of virus-specific T cell responses at the early stages of infection may influence the final outcome of both hepatitis B and C. While T cell hyporesponsiveness seems to be an important determinant for HBV persistence once chronic hepatitis has developed, this mechanism appears to be less critical in chronic HCV infection, because the vigor and quality of HCV-specific T cell responses seem to improve as a function of the duration of infection. This is shown by the finding that HCV-specific CD4- and CD8-mediated responses are easily detectable in the peripheral blood of patients with long-lasting chronic hepatitis C and that production of Th1 cytokines predominates within their livers. HCV therefore seems to be able to persist even in the face of an active T cell response and to acquire the capacity to survive within a host environment apparently unfavorable to its persistence. The high variability of HCV may explain its efficiency in escaping immune surveillance.

A distinct pattern of cytokine production from blood mononuclear cells in multitransfused patients with β-thalassaemia: Salsaa B, Zoumbos NC. Clin Exp Immunol 107:589–592, 1997

A distinct pattern of cytokine production from blood mononuclear cells in multitransfused patients with β-thalassaemia: Salsaa B, Zoumbos NC. Clin Exp Immunol 107:589–592, 1997

IFN-gamma in human Chagas' disease: protection or pathology?

An apparently paradoxical role for IFN-gamma in human Chagas' disease was observed when studying the pattern of cytokine production by peripheral blood mononuclear cells (PBMC) obtained from two groups of chagasic patients after specific stimulation with Trypanosoma cruzi-derived antigens. The groups studied were 1) patients treated with benznidazole during the acute phase of Trypanosoma cruzi infection and 2) chronically infected untreated patients. In the treated group, higher levels of IFN-gamma were produced by PBMC from individuals cured after treatment when compared to non-cured patients. In contrast, in the chronically infected group (not treated) higher levels of IFN-gamma were produced by PBMC from cardiac patients in comparison with asymptomatic (indeterminate) patients. This apparently paradoxical role for IFN-gamma in human Chagas' disease is discussed in terms of the possibility of a temporal difference in IFN-gamma production during the initial stages of the infection (acute phase) in the presence or absence of chemotherapy. The maintenance of an immune response with high levels of IFN-gamma production during the chronic phase of the infection may favor cure or influence the development of the cardiac form of the disease.

The Effect of Oral Feeding of Lactobacillus casei Strain Shirota on Immunoglobulin E Production in Mice

We investigated the effect of oral feeding of heat-killed Lactobacillus casei strain Shirota on immunoglobulin E (IgE) production in mice. The strain was orally administered to BALB/c mice that had been preinjected intraperitoneally with ovalbumin, and the level of IgE in serum was determined. Results indicated that the oral feeding of L. casei strain Shirota was effective in inhibiting IgE production in serum, and the IgE production in response to ovalbumin was significantly inhibited in the mice. The in vitro production of IgE by the spleen cells from mice fed L. casei strain Shirota in response to restimulation with ovalbumin was inhibited in contrast to that of spleen cells from the control group.We also examined the pattern of cytokine production by spleen cells from mice fed L. casei strain Shirota followed by restimulation with ovalbumin in vitro. In the mice fed L. casei strain Shirota, the production by the spleen cells of Th1 cell-associated cytokines, such as interferon-γ and interleukin-2, was higher than that by the spleen cells from the control group. In contrast, the production of Th2 cell-associated cytokines, such as interleukin-4, interleukin-5, interleukin-6, and interleukin-10, by spleen cells in the group fed L. casei strain Shirota was lower than that by the cells from the control group. Furthermore, the interleukin-12 production of the spleen cells from mice fed L. casei strain Shirota was also higher than that of the control group.

Disease specific patterns of cytokine production by T-lymphocytes in coronary atheroscierosis: evidence for a role of infections agents in the pathogenesis of ustable Angina?

Disease specific patterns of cytokine production by T-lymphocytes in coronary atheroscierosis: evidence for a role of infections agents in the pathogenesis of ustable Angina?

Engrafted maternal T cells in human severe combined immunodeficiency: Evidence for a T H2 phenotype and a potential role of apoptosis on the restriction of T-cell receptor variable β repertoire

1. Street MD, Donovan GR, Baldo BA, Sutherland S. Immediate allergic reactions to Myrmecia ant stings; immunochemical analysis of Myrmecia venoms. Clin Exp Allergy 1994;24:590-7. 2. Donovan GR, Baldo BA, Sutherland S. Molecular cloning and characterisation of a major allergen (Myr p 1) from the venom of the Australian jumper ant. Biochim Biophys Acta 1993;1171:272-80. 3. Weiner JM, Baldo BA, Donovan GR, Sutherland SK. Allergy to jumper ant (Myrmecia pilosula) stings in south-eastern Australia [abstract]. Ann Allergy Asthma Immunol 1995;74:60. 4. Stuckey M, Cobain T, Sears M, Cheney J, Dawkins RL. Bee venom hypersensitivity in Busselton [letter]. Lancet 1982;2:41.

Immune responses of IL-5 transgenic mice to parasites and aeroallergens.

Eosinophils have long been thought to be effectors of immunity to helminths but have also been implicated in the pathogenesis of asthma. Patterns of cytokine production in the host may influence the pathogenesis of these diseases by regulating the activities of eosinophils and other components of the immune response. Mice which constitutively over-express IL-5 have profound and life-long eosinophilia in a restricted number of tissues. Although eosinophils from IL-5 transgenics are functionally competent for a number of parameters considered to be important in inflammation, untreated animals are overtly normal and free of disease. In addition, the responses of these animals when exposed to aeroallergens and helminths present a number of apparent paradoxes. Eosinophil accumulation in tissues adjacent to major airways is rapid and extensive in transgenics exposed to the aeroallergen, but even after treatment with antigen over many months these mice show no evidence of respiratory distress or pathology. Helminth-infected IL-5 transgenics and their non-transgenic littermates develop similar inflammatory responses at mucosal sites and are comparable for a number of T cell and antibody responses, but they differ considerably in their ability to clear some parasite species. The life-cycle of Nippostrongylus brasiliensis is significantly inhibited in IL-5 transgenics, but that of Toxocara canis is not. Our results also suggest that eosinophilia and/or over-expression of IL-5 may actually impair host resistance to Schistosoma mansoni and Trichinella spiralis. The pathogenesis of diseases in which eosinophils are involved may therefore be more complex than previously thought.

Cytokine production by lymphocytes in pregnancy.

In the presence of progesterone lymphocytes of pregnant women release a 34-kDa protein named the progesterone-induced blocking factor (PIBF). PIBF mediates the immunomodulatory and anti-abortive effects of progesterone and its presence is related to the outcome of pregnancy. PIBF induces production of Th2 type cytokines by activated lymphocytes. The in vivo relationship between PIBF- and cytokine production of pregnancy lymphocytes and the outcome of pregnancy was investigated. Interleukin (IL)-12 and IL-10 production and PIBF expression in peripheral lymphocytes of 111 healthy pregnant women and 120 women at risk for premature pregnancy termination were detected by immunocytochemistry. We found increased IL-12 and low PIBF and IL-10 expression on lymphocytes of "risk" patients, and a high rate of IL-10 and PIBF positivity on lymphocytes from healthy pregnant women. The cytokine production pattern of the lymphocytes was related to the presence or absence of previous abortions as well as to the outcome of pregnancy. These data suggest the involvement of an altered cytokine production pattern in the immunologic effects of progesterone.