Unsymmetrical Pd(II) Pincer Complexes with Benzothiazole and Thiocarbamate Flanking Units: Expedient Solvent-Free Synthesis and Anticancer Potential.

Driven by the growing threat of cancer, many research efforts are directed at developing new chemotherapeutic agents, where the central role is played by transition metal complexes. The proper ligand design serves as a key factor to unlock the anticancer potential of a particular metal center. Following a recent trend, we have prepared unsymmetrical pincer ligands that combine benzothiazole and thiocarbamate donor groups. These compounds are shown to readily undergo direct cyclopalladation, affording the target S,C,N-type Pd(II) pincer complexes both in solution and in the absence of a solvent. The solid-phase strategy provided the complexes in an efficient and ecologically friendly manner. The resulting palladacycles are fully characterized using nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy and, in one case, by single-crystal X-ray diffraction (XRD). The solvent-free reactions are additionally analyzed by powder XRD. The pincer complexes exhibit remarkable cytotoxicity against several solid and blood cancer cell lines, including human colorectal carcinoma (HCT116), breast cancer (MCF7), prostate adenocarcinoma (PC3), chronic myelogenous leukemia (K562), multiple plasmacytoma (AMO1), and acute lymphoblastic leukemia (H9), with the dimethylamino-substituted derivative being particularly effective. The latter also induced an appreciable level of apoptosis in both parental and doxorubicin-resistant cells K562 and K562/iS9, vindicating the high anticancer potential of this type of palladacycles.

(Aminoalkyl)diphenylphosphine sulfides: synthesis and application as building blocks in the design of multidentate ligands for cytotoxic Pd(II) complexes.

Amino-functionalized phosphoryl compounds are among the most useful molecular scaffolds in medicinal chemistry, while the potential of their thiophosphorylated analogs, especially those having an alkylamino moiety, is still uncovered. This is mainly due to the lack of convenient synthetic routes to these organophosphorus derivatives. To address this issue, we have suggested the facile approaches to α-(aminomethyl)- and substituted/unsubstituted α-(aminobenzyl)diphenylphosphine sulfides based on either the sequential transformations of (hydroxymethyl)diphenylphosphine sulfide, with the Staudinger reaction of an azide derivative as the key stage, or the addition of Ph2P(S)H to hydrobenzamides followed by the acid hydrolysis. The compounds obtained were reacted with picolinyl chloride to yield functionalized amides which readily underwent direct cyclopalladation, resulting in new representatives of non-classical N-metalated Pd(II) pincer complexes. The latter exhibit promising cytotoxic activity against several human cancer cell lines and apoptosis inducing ability along with the remarkable cytotoxic effects on doxorubicin-resistant cell sublines.

Modulation of the Cytotoxic Properties of Pd(II) Complexes Based on Functionalized Carboxamides Featuring Labile Phosphoryl Coordination Sites.

Platinum-based drugs are commonly recognized as a keystone in modern cancer chemotherapy. However, intrinsic and acquired resistance as well as serious side effects often caused by the traditional Pt(II) anticancer agents prompt a continuous search for more selective and efficient alternatives. Today, significant attention is paid to the compounds of other transition metals, in particular those of palladium. Recently, our research group has suggested functionalized carboxamides as a useful platform for the creation of cytotoxic Pd(II) pincer complexes. In this work, a robust picolinyl- or quinoline-carboxamide core was combined with a phosphoryl ancillary donor group to achieve hemilabile coordination capable of providing the required level of thermodynamic stability and kinetic lability of the ensuing Pd(II) complexes. Several cyclopalladated derivatives featuring either a bi- or tridentate pincer-type coordination mode of the deprotonated phosphoryl-functionalized amides were selectively synthesized and fully characterized using IR and NMR spectroscopy as well as X-ray crystallography. The preliminary evaluation of the anticancer potential of the resulting palladocycles revealed a strong dependence of their cytotoxic properties on the binding mode of the deprotonated amide ligands and demonstrated certain advantages of the pincer-type ligation.

The association between beverage-specific alcohol consumption and mortality among road users in Russia, 1965-2019.

A vast body of literature suggests a relationship between alcohol consumption and road traffic fatalities. Despite an impressive downward trend in road traffic fatalities in Russia, the death rate is still unacceptably high. Far fewer studies have differentiated the association by road users and types of alcoholic beverages. This population-based study aims to estimate the associations of total and beverage-specific alcohol per capita (15+) consumption (APC) based on official alcohol sales statistics and road traffic mortality using police data on the number of deaths by road users. The study covers the period 1965-2019. We employed a first-order difference linear regression model with robust and autocorrelation consistent standard errors, controlling for a level of motorisation. To examine the possible evolution of the phenomenon, we repeated models separately for three consecutive periods (1965-1984, 1985-2002, 2003-2019). The findings suggest that an annual 1-litre increase in APC (in litres of pure alcohol) associated with a corresponding increase in the death rates (per 100,000 inhabitants) of both unprotected road users and motor vehicle occupants by about 0.3 (p < 0.01) and 0.4 (p < 0.05), respectively. A beverage-specific analysis for 1965-2019 revealed a positive and significant association between mortality of pedestrians and cyclists and the consumption of strong alcoholic beverages (p < 0.05) as well as mortality of drivers and passengers and the consumption of weaker alcoholic beverages, primarily beer (p < 0.01). Various road safety strategies should be applied to prevent road traffic fatalities of road users.

Pincer-dipeptide and pseudodipeptide conjugates: Synthesis and bioactivity studies.

Following a recent trend on the application of different pincer scaffolds for the development of new metal-based antitumor agents, in this work, dipeptides and dipeptide surrogates based on picolinyl- and 4-chloropicolinylamides with S-donor amino acid residues (cysteine, homocysteine, or methionine) bearing glycinate, alaninate, or phosphonate moieties either at the C-terminus or in the S-donor side arm have been designed as nonclassical pincer ligands with central amide units and shown to smoothly undergo site-selective direct cyclopalladation under mild conditions, affording the target Pd(II) pincer complexes in good to high yields. The realization of S,N,N-coordination through the sulfur atom of the thioether group and nitrogen atoms of the pyridine and deprotonated amide units was unambiguously confirmed using different NMR techniques (1H, 13C, 31P, and 2D NMR methods, including 1H15N HMBC) and IR spectroscopy; the structure of one representative was elucidated by X-ray crystallography. The resulting pincer-(pseudo)dipeptide conjugates were screened for cytotoxicity against several cancer cell lines and noncancerous human embryonic kidney cells and at least some of them provided an appreciable level of activity comparable to that of cisplatin. The S-modified homocysteine-based derivatives exhibited also significant antiproliferative effects against doxorubicin-resistant transformed breast cells HBL100/Dox, implying the possibility of overcoming drug resistance. The complexes can induced apoptosis but did not affect mitochondria. The comparative DNA/protein binding studies of one of the most active pincer-(pseudo)dipeptide conjugates with the monoamino acid-based prototype revealed certain advantages of the former and gave further insights into the potential of this type of palladium-based antitumor agents.

Mechanochemistry for the synthesis of non-classical N-metalated palladium(II) pincer complexes.

The peculiarities of cyclopalladation of a series of non-classical pincer-type ligands based on monothiooxalyl amides bearing ancillary N- or S-donor groups in the amide units have been scrutinized both under conditions of conventional solution-based synthesis and in the absence of a solvent according to a solid-phase methodology including mechanochemical activation. Grinding the functionalized monothiooxamides with PdCl2(NCPh)2 in a mortar or vibration ball mill is shown to serve as an efficient and green alternative to the synthesis of these complex metal-organic systems in solution that can offer such advantages as the absence of any auxiliary and significant rate and yield enhancement, especially for the challenging ligands. The realization of S,N,N- or S,N,S-monoanionic tridentate coordination in the resulting pincer complexes has been confirmed by multinuclear NMR (including 2D NMR) and IR spectroscopy and, in some cases, X-ray diffraction. The course and outcome of the solid-phase reactions have been studied by a combination of different spectroscopic methods as well as SEM/EDS analysis. The preliminary evaluation of cytotoxic activity against several human cancer cell lines has revealed the high potency of some of the cyclopalladated derivatives obtained, rendering further development of solvent-free synthetic routes to this type of complexes very urgent.

Palladium(II) Pincer Complexes of Functionalized Amides with S-Modified Cysteine and Homocysteine Residues: Cytotoxic Activity and Different Aspects of Their Biological Effect on Living Cells.

In the search for potential new metal-based antitumor agents, two series of nonclassical palladium(II) pincer complexes based on functionalized amides with S-modified cysteine and homocysteine residues have been prepared and fully characterized by 1D and 2D NMR (1H, 13C, COSY, HMQC or HSQC, 1H-13C, and 1H-15N HMBC) and IR spectroscopy and, in some cases, X-ray diffraction. Most of the resulting complexes exhibit a high level of cytotoxic activity against several human cancer cell lines, including colon (HCT116), breast (MCF7), and prostate (PC3) cancers. Some of the compounds under consideration are also efficient in both native and doxorubicin-resistant transformed breast cells HBL100, suggesting the prospects for the creation of therapeutic agents based on the related compounds that would be able to overcome drug resistance. An analysis of different aspects of their biological effects on living cells has revealed a remarkable ability of the S-modified derivatives to induce cell apoptosis and efficient cellular uptake of their fluorescein-conjugated counterpart, confirming the high anticancer potential of Pd(II) pincer complexes derived from functionalized amides with S-donor amino acid pendant arms.

Highly Cytotoxic Palladium(II) Pincer Complexes Based on Picolinylamides Functionalized with Amino Acids Bearing Ancillary S-Donor Groups.

The reactions of picolinyl and 4-chloropicolinyl chlorides with methyl esters of S-methyl-l-cysteine, l- and d-methionine, and l-histidine afforded a series of functionalized carboxamides, which readily formed pincer-type complexes upon interaction with PdCl2(NCPh)2 in solution under mild conditions. The direct cyclopalladation of the ligands derived was also accomplished in the solid phase, in particular, mechanochemically, although it was complicated by the partial deactivation of the starting amides. The resulting complexes with 5,5- and 5,6-membered fused metallocycles were fully characterized by IR and NMR spectroscopy, including variable-temperature and 2D-NMR studies. In the case of some cysteine- and methionine-based derivatives, the realization of κ3-N,N,S-coordination was supported by X-ray diffraction. The cytotoxic effects of these complexes were examined on HCT116, MCF7, and PC3 human cancer cell lines as well as HEK293 as a representative of normal cells. The comparative studies allowed us to determine that the presence of the sulfide ancillary donor group is crucial for cytotoxic activity of this type of Pd(II) complexes. The main structure-activity relationships and the most promising palladocycles were outlined. The additional studies by gel electrophoresis revealed that 4-chloropicolinyl derivatives, despite the nature of an amino acid, can bind with DNA and inhibit topoisomerase I activity.

Chemical and biological properties of a supramolecular complex of tuftsin and cucurbit[7]uril.

Cucurbit[7]uril (CB7) is an uncharged and water-soluble macrocyclic host. CB7 binds to doubly protonated tuftsin, which is the tetrapeptide Thr-Lys-Pro-Arg, with moderate affinity (Ka=2.1×103M-1). In this study, the host-guest complexation was confirmed by fluorescence titration. This affinity would allow for easy release of the peptide under physiological conditions. According to density functional theory calculations, the structural binding motif involves hydrogen bonding. The most energetically stable form had the Arg side chain inside the CB7 cavity. The effects of the tuftsin-CB7 complex on the proliferation and cytokine activity of immune cells were studied. The complex had broader spectrum immunomodulation than free peptides, and caused statistically significant (p<0,05) changes in cytokine production (tumor necrosis factor-α, interleukin-2, interferon-γ, and interleukin-10) by mononuclear cells. By contrast, the free peptide only activated tumor necrosis factor-α production.

Differences of IL-1ß Receptors Expression by Immunocompetent Cells Subsets in Rheumatoid Arthritis.

IL-1ß is involved in the induction and maintenance of chronic inflammation in rheumatoid arthritis (RA). Its activity is regulated and induced by soluble and membrane-bound receptors, respectively. The effectiveness of the cytokine depends not only on the percentage of receptor-positive cells in an immunocompetent subset but also on the density of receptor expression. The objective of this study was to investigate the expression of IL-1ß membrane-bound receptors (IL-1R1 and IL-1R2) in terms of the percentage of receptor-positive cells and the number of receptors per cell in different subsets of immune cells in RA patients before and after a course of basic (excluding anticytokine) therapy and in healthy individuals. The resulting data indicate differences in the expression of IL-1ß receptors among T cells, B cells, and monocytes in healthy volunteers and in rheumatoid arthritis patients. The importance of determining both the relative percentage of cells expressing receptors to immunomodulatory cytokines and the number of membrane-bound receptors per cell is highlighted by evidence of unidirectional or multidirectional changing of these parameters according to cell subset and health status.

Solid-phase cyclopalladation in S,C,S'-pincer systems: rising alternative for synthesis in solution.

In pursuit of a new and simple approach to complex organometallic systems, the possibility of formation of a palladium-carbon bond in the solid state via direct cyclopalladation has been studied toward several S,C,S'-pincer ligands with thione sulfur donors of different nature. It is found that mixtures of the ligand and PdCl2(NCPh)2 obtained by the manual grinding of reactants in a mortar efficiently undergo solid-phase cyclometalation upon heating in open test tubes without the addition of a solvent to afford the desired pincer-type products in high yields. In the case of the most active bis(thiocarbamoyl) ligand, solid-phase cyclopalladation proceeds even at room temperature. For the challenging bis(thiophosphoryl) derivative, the preformed non-metallated complexes can be successfully used as a starting material to essentially enhance the yield of the desired pincer complex compared to the conventional synthesis in solution. The solid-phase transformation is followed by IR spectroscopy and SEM analysis. The results obtained show that the suggested solid-phase methodology can serve as a powerful alternative to conventional synthesis of pincer complexes in solution.

The first solid phase synthesis of pincer palladium complexes.

Both dimeric µ-chlorine bridged and monomeric bidentate Pd(II) complexes with SCN hybrid pincer-type ligands, bearing thiophosphoryl group and imine moiety of the benzothiazole ring as coordination arms, formed in the reaction with (PhCN)(2)PdCl(2) under kinetic control (20 °C, dichloromethane solution) were readily converted into the corresponding SCN pincer complexes via solid phase synthesis (neat, 200 °C, 15 min). The synthesis of pincer complexes can be performed also by heating (200 °C, 5 min) of a homogeneous mixture of the initial reactants, namely, the ligand and (PhCN)(2)PdCl(2), obtained by manual grinding in a mortar. The efficacy of solid phase approaches is comparable with the analogous synthesis in solutions under severe conditions.

High-dose immunosuppressive therapy with autologous hematopoietic stem cell transplantation as a treatment option in multiple sclerosis.

High-dose immunosuppressive therapy (HDIT) with autologous hematopoietic stem cell transplantation (auto-HSCT) is a new and promising approach to the treatment of multiple sclerosis (MS) patients because currently there are no effective treatment methods for this disease. In this article, we present results of a prospective clinical study of efficacy of HDIT + auto-HSCT in MS patients. The following treatment strategies were employed in the study: "early," "conventional," and "salvage/late" transplantation. Fifty patients with various types of MS were included in this study. No toxic deaths were reported among 50 MS patients; transplantation procedure was well-tolerated by the patients. The efficacy analysis was performed in 45 patients. Twenty-eight patients achieved an objective improvement of neurological symptoms, defined as at least 0.5-point decrease in the Expanded Disability Status Scale (EDSS) score as compared to the baseline and confirmed during 6 months, and 17 patients had disease stabilization (steady EDSS level as compared to the baseline and confirmed during 6 months). The progression-free survival at 6 years after HDIT + auto-HSCT was 72%. Magnetic resonance imaging data were available in 37 patients before transplantation showing disease activity in 43.3%. No active, new, or enlarging lesions were registered in patients without disease progression. In conclusion, HDIT + auto-HSCT suggests positive results in management of patients with different types of MS. Identification of treatment strategies based on the level of disability, namely "early," "conventional," and "salvage/late" transplantation, appears to be feasible to improve treatment outcomes.

Alternative splicing of mRNA of mouse interleukin-4 and interleukin-6.

Interleukin-4 and interleukin-6 are multifunctional regulatory proteins, which participate both in haemopoiesis and in immunopoiesis. The alternative splicing of these interleukins in humans is known to proceed in a tissue-specific manner. Additionally, changes in splicing can also be dependent on tissue pathology. In this work, we report on the presence of alternatively spliced mRNA (IL-4delta2mRNA), lacking exon 2, in mouse bone marrow and spleen cells. We find that in unstimulated cells IL-4mRNA levels strongly dominate over IL-4delta2mRNA levels. Both increase in response to stimulation, with the concentration of the alternative variant rising earlier and faster than that of the full-length variant. In all other tissues studied dominance of IL-4delta2mRNA over the full-length variant was not observed. In addition, we find expression of three forms of IL-6 mRNA: the full-length IL-6 mRNA, IL-6Delta3 mRNA, and IL-6Delta5 mRNA in the second and third trimester placenta tissue and in the spleen of mice immunized with a high dose of sheep erythrocytes. It is anticipated that translation of these mRNA variants can generate proteins capable of binding to some subunits of the IL-6 receptor, thus possessing effector function. Alternative splicing is discussed as a source of cytokines with new regulatory properties.

The role of asymmetry of nervous and immune systems in the formation of cellular immunity of (CBaxC57Bl/6) F1 mice.

We have previously shown the existence of functional asymmetry of the immune system and the role of brain hemispheres and different lobes of thymus in the development of humoral immune response in (CBA x C57Bl/6) F1 mice. The role of asymmetry of the nervous and immune systems in the formation of the cellular immune response [delayed-type hypersensitivity (DTH) reaction] in these mice has been studied in our work. In order to test the influence of asymmetry of the primary immune organs, thymus, on the cellular immune response, mice were thymectomized and then we studied the effect of the injection of cells from contralateral thymus lobes of right-dominant and left-dominant donors by motor asymmetry on how pronounced the DTH reaction in the back left paw was. The injection of thymocytes from right-dominant donors appeared to result in significant differences in DTH reaction between left- and right-handed mice. At the same time, our experiments failed to discover any pronounced role of thymus asymmetry in the formation of DTH reaction. In order to test the influence of asymmetry of peripheral immune organs, regional lymph nodes, on the regulation of cellular immune response, we compared the DTH reaction in left and right paws of mice. We found that the intensity of the DTH reaction to sheep red blood cells in the front paws of (CBA x C57Bl/6) F1 mice depends not only on whether the antigen is injected into the left or right paw but also on the motor asymmetry of the hemispheres. While comparing the DTH reaction in the back left and right paw of mice we showed that in both right- and left-handed mice it was much more pronounced in the left paw than in the right one. The data obtained testify to the functional asymmetry of bilateral lymph nodes located near the forming cellular immune reaction. Thus, the results obtained show that the intensity of DTH reaction in (CBA x C57Bl/6) F1 mice depends on the functional asymmetry of regional lymph nodes and motor of brain hemispheres. The thymus functional asymmetry is of slight importance in DTH reaction.

Production of hemo- and immunoregulatory cytokines by erythroblast antigen+ and glycophorin A+ cells from human bone marrow.

BACKGROUND: Erythroid nuclear cells (ENC) of the bone marrow (BM) have not previously been considered as important producers of wide spectrum of haemo- and immunoregulatory cytokines. The aim of the current work was to confirm the production of the main hemo- and immunoregulatory cytokines in human ENC from BM. RESULTS: We used native human BM ENC in our experiments. We for the first time have shown, that the unstimulated erythroblasts (Gl A+ or AG-EB+) produced a wide spectrum of immunoregulatory cytokines. Human BM ENC produce cytokines such as interleukin (IL)-1beta, IL-2, IL-4, IL-6, interferon (IFN)-gamma, transforming growth factor (TGF)-beta1, tumor necrosis factor (TNF)-alpha and IL-10. They can be sub-divided into glycophorin A positive (Gl A+) and erythroblast antigen positive (AG-EB+) cells. To study potential differences in cytokine expression between these subsets, ENC were isolated and purified using specific antibodies to Gl A and AG-EB and the separated cells were cultivated for 24 hours. The cytokine contents of the supernatant were measured by electrochemiluminescence immunoassay. Quantitative differences in TGF-beta1 and TNF-alpha production were found between Gl A+ and AG-EB+ BM ENC. Furthermore, in vitro addition of erythropoietin (EPO) reduced IFN-gamma and IL-2 production specifically by the AG-EB+ ENC. Thus, Gl A+ and AG-EB+ ENC produce IL-1beta, IL-2, IL-4, IL-6, IFN-gamma, TGF-beta1 and TNF-alpha. Gl A+ ENC also produce IL-10. CONCLUSION: Cytokine production by erythroid nuclear cells suggests that these cells might be involved in regulating the proliferation and differentiation of hematopoietic and immunocompetent cells in human BM.

Erythroid cells in immunoregulation: characterization of a novel suppressor factor.

Nucleated erythroid cells (EC) have been previously reported to possess a potent natural suppressor (NS) activity for B-cell responses. In this study, we demonstrate that murine EC are able to reduce not only lipopolysaccharide (LPS)-driven B-cell proliferation, but also proliferative and cytotoxic T-cell responses generated in a primary allogeneic mixed lymphocyte culture (MLC); and that a soluble low molecular weight factor may be involved in such EC-derived immunoregulation. In addition, the erythroid cell-derived suppressor factor (ESF) was found to be capable of effectively reducing the allergen-driven proliferation of peripheral blood mononuclear cells (PBMC) isolated from allergic patients. From the data presented herein, it appears that ESF is heat-stable (80 degrees C for 20 min) and has molecular weight (MW) lower or close to 0.5 kDa. ESF activity is resistant to both enzyme (trypsin plus chymotrypsin) proteolysis and action of the enzymes such as lipase and phospholipase C. On the other hand, ESF is effectively inactivated by neuraminidase treatment, suggesting the presence in its structure of sialic residue(s). The neuraminidase-sensitive, ESF-like activity is readily detected in the medium conditioned with normal mouse bone marrow (BM) cells. On fractionation of low MW erythroid products on a reversed-phase C16 column in a linear acetonitrile gradient (5-95%), ESF activity is detected in the first peak alone with the shortest time of its retention by the column. The results suggest that (1) by producing ESF, EC may regulate both B- and T-cell-mediated immune processes and (2) based on its physicochemical and biological characteristics, ESF can be distinguished from each of earlier characterised suppressor mediators of bone marrow origin.

Transplantation treatment of spinal cord injury patients.

The minimally manipulated cells from fetal nervous and hemopoietic tissues (gestational age 16-22 weeks) were subarachnoidally implanted into 15 patients (18-52 years old) with severe consequences of traumatic spinal cord injury (SCI) at cervical or thoracic spine level. The times after SCI were from 1 month to 6 years. Each patient underwent from one to four cell transplantations (CT) with various time intervals. In 11 of 15 cases, CT was combined with an operative partial disruption of a connective tissue cyst and with implantation into a spinal cord lesion of a spinal cord fragment together with olfactory ensheathing cells. Before CT the patients showed complete motor and sensory function disorder consistent with a grade A of SCI according to Frankel classification. With CT treatment, six patients improved their neurological status from A to C grade of SCI, exhibiting incomplete restoration of both motor and sensory function. The status of other five CT-treated patients became consistent with SCI grade B and was characterized by appearance of contracting activity in some muscles and incomplete restoration of sensitivity. The remaining four patients did not exhibit any clinical improvements. No serious complications of CT were noted. The results suggest a clinical relevance of the CT-based approach to treating severe consequences of SCI.

Quantitative analysis of human immunoregulatory cytokines by electrochemiluminescence method.

Quantitative analysis of human immunoregulatory cytokines in physiological media and cell cultures plays an important role in fundamental and clinical research. Here we describe the quantification of interleukin (IL)-2, IL-4, IL-10 and interferon-gamma (IFN-gamma) in human serum and peripheral blood mononuclear cell (PBMC)-conditioned medium by electrochemiluminescence method (ECL). We demonstrate that this approach allows to detect cytokine concentration from 1 pg/ml. The high sensitivity in combination with accuracy and wide range of determined concentration indicates that ECL meets the standards of quantitative analysis of cytokines. Simplicity and short time of procedure, small assay volume and high reproducibility make ECL method competitive in practical use with conventional quantitative methods of cytokine detection.

Production of IL-10, TNF-alpha, IFN-gamma, TGF-beta1 by different populations of erythroid cells derived from human embryonal liver.

It has previously been determined that erythroid cells of mice are capable of expressing such cytokines as interleukin (IL) 1 alpha and beta, IL-4, IL-6, interferon gamma (IFN-gamma), granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor beta (TGF-beta). It has been shown that glycophorin A(+) (GlA(+)) and antigen erythroblasts (AG-EB(+)) (both human erythroid cells of embryonic origin) are also capable of producing a series of cytokines such as IL-1 beta, IL-2, IL-4 and IL-6. The aim of this work was to study the capacity of erythroid cells from human embryonic liver to produce such cytokines as IFN-gamma, TGF-beta1, tumour necrosis factor alpha (TNF-alpha) and IL-10. The erythroid cells were isolated by means of antibodies specific to erythroblasts (GlA and AG-EB), as well as those from single erythroid colonies. The production level of some cytokines varies insignificantly under the action of erythropoietin (Epo) and quantitatively differs in GlA(+) and AG-EB(+) erythroid cells. Hence, the erythroid cells express IFN-gamma, TGF-beta1, TNF-alpha and IL-10. The erythroid cells could be involved through the production of these cytokines in the regulation of such processes as self-renewal, proliferation and differentiation of cells of other blood-forming sites.