[Perspectives of the Cell Therapy in Ophthalmology1. The Application of Stem Cells in the Regeneration of Damaged Surface of the Eye]. / Perspektivy bunecné terapie v oftalmologii1. Vyuzití kmenových bunek v regeneraci poskozeného povrchu oka.

UNLABELLED: Regeneration of corneal epithelium is secured by a population of limbal stem cells (LSC), which are located in the basal part of the limbal epithelium. Deficiency in LSC leads to chronic inflammation, scarring and conjunctivization of cornea. Therapy of LSC deficiency consists in transplantation of limbal tissue, cultivated limbal epithelium or more recently in tranplantation of autologous cells including mesenchymal stem cells, oral mucosal epithelial cells or hair follicle-derived stem cells. A significant progress has been achieved in the field of cell therapy and also in the development of convenient scaffolds for the growth and transfer of cells on damaged cornea. KEY WORDS: ocular surface damage, stem cells, cell therapy.

[Perspectives of the Cell Therapy in Ophthalmology.2. The Potential of Stem Cells for the Retinal Diseases Treatment]. / Perspektivy bunecné terapie v oftalmologii2. Potenciál kmenových bunek pro lécbu onemocnení sítnice.

UNLABELLED: Retinal diseases represent a large group of hereditary and acquired diseases that often lead to loss of vision. There is currently no effective treatment of retinal degeneration, only supportive therapy is used for treating numerous diseases. Perspective treatment of retinal diseases represent a cell therapy using stem cells. Suitable candidates for the stem cell therapy are mesenchymal stem cells due to their differentiating properties, protective effect and also immunomodulation. KEY WORDS: retinal disease, therapy, stem cells, mesenchymal stem cells.

A low-molecular-weight dialysable leukocyte extract selectively enhances development of CD4⁺RORγt⁺ T cells and IL-17 production.

A low-molecular-weight (under 10 kDa) dialysable leukocyte extract (called transfer factor, TF) has been shown to be a prospective substance to improve or modulate immune response in autoimmunity, inflammation, infectious diseases or cancers. However, the use of TF has been limited by the absence of any data on the mechanism of its action. Here we show that TF prepared from peripheral blood leukocytes of healthy human donors displays multiple regulatory effects on individual parameters of the immune system. TF decreases proliferation of T and B lymphocytes and partially alters the production of cytokines and nitric oxide by activated macrophages. TF also inhibits production of T helper 1 (Th1) cytokines interleukin 2 (IL-2) and interferon γ, slightly stimulates production of Th2 cytokine IL-10 and considerably enhances the secretion of IL-17 by activated mouse spleen T cells. At the molecular level, TF enhances expression of genes for transcription factor RORγt and for IL-17. The enhanced expression of the RORgt gene corresponds with an increase in the number of RORγt⁺CD4⁺ Th17 cells and with enhanced IL-17 production. In contrast, the expression of the Foxp3 gene and the proportion of CD4⁺CD25⁺Foxp3⁺ regulatory T cells are not significantly changed in the presence of TF. These results suggest that the activation of pro-inflammatory Th17 cells, which have multiple immunoregulatory properties, could be the main mechanism of the immunomodulatory action of a low-molecular-weight leukocyte extract.

Polyomavirus EGFP-pseudocapsids: analysis of model particles for introduction of proteins and peptides into mammalian cells.

A vector for preparation of mouse polyomavirus capsid-like particles for transfer of foreign peptides or proteins into cells was constructed. Model pseudocapsids carrying EGFP fused with the C-terminal part of the VP3 minor protein (EGFP-VLPs) have been prepared and analysed for their ability to be internalised and processed by mouse cells and to activate mouse and human dendritic cells (DC) in vitro. EGFP-VLPs entered mouse epithelial cells, fibroblasts and human and mouse DC efficiently and were processed by both, lysosomes and proteasomes. Surprisingly, they did not induce upregulation of DC co-stimulation molecules or maturation markers in vitro; however, they did induce interleukin 12 secretion.

Prevention of corneal allograft rejection in a mouse model of high risk recipients.

AIM: To determine the effectiveness of treatment with immunosuppressive drugs and monoclonal antibodies (mAb) after penetrating keratoplasty in two different models of high risk mouse recipients. METHODS: Corneas were grafted orthotopically in mouse models of high risk recipients with either neovascularisation of the graft bed or presensitisation to graft donor antigens. Recipients were treated with mAb against CD4(+) or CD8(+) cells or against T cells, or were treated with cyclosporin A (CsA) or mycophenolate mofetil (MMF), or a combination of both drugs. RESULTS: Control untreated recipients with neovascularised graft bed or presensitised to the graft donor antigens rejected corneal allografts in 12.5 (SD 2.3) and 9.9 (1.6) days, respectively. Treatment of graft recipients with a neovascularised graft bed with mAb anti-CD4 or anti-T cells, but not with mAb anti-CD8 or with immunosuppressive drugs, resulted in a significant prolongation of graft survival; 75% and 28.5%, respectively, of grafts survived for more than 45 days after grafting. However, none of the treatments were successful in presensitised recipients. CONCLUSIONS: Treatment of high risk recipients with mAb anti-CD4 is more effective in preventing corneal allograft rejection than the treatment with mAb anti-CD8 or the immunosuppressive drugs MMF and CsA. However, the effectiveness of the treatment depends on the recipients' pretransplantation risk type.

Quantitative evaluation of the corneal endothelium in the mouse after grafting.

BACKGROUND/AIM: Corneal graft survival depends critically on the quality of the endothelium. In this study the authors aimed to evaluate corneal endothelium in mice at different times after transplantation and to correlate endothelial integrity with corneal graft survival. METHODS: Syngeneic and allogeneic corneal grafts at various times (days 0-60) after engraftment were examined in flat mount preparation by confocal microscopy, by evaluating the hexagonal pattern of the endothelial monolayer using actin staining of the cell cortex. Corneas from untreated mice and from mice, who were grafted after removal of draining lymph nodes served as controls. RESULTS: In control corneas, more than 90% of the posterior surface was covered by endothelium. Syngeneic grafts were always covered by 54-99% of endothelium. In contrast, the posterior surface of corneal allografts showed great variation in the degree of endothelial cell coverage (0-98%). In addition, clinical opacity grading measure was not a reliable predictor of endothelial coverage. CONCLUSION: In corneal allografts there is progressive loss of endothelium over time, unlike with syngeneic grafts. However, in the early stages of allograft rejection, the grade of graft opacity does not accurately reflect the degree of endothelial cell coverage. Although corneal opacity grade is considered the main determinant of graft rejection, the data suggest that both the grade of corneal opacity plus a sufficient post-graft time duration (>8 weeks in the mouse) are required for the diagnosis of irreversible graft rejection.

Boar seminal immunosuppressive fraction attenuates the leptin concentration and restores the thymus mass during pregnancy in mice.

The immunosuppressive fraction (ISF) of boar seminal vesicle fluid was recently demonstrated to inhibit production of T helper (Th)1 cytokines and enhance production of Th2 cytokines. The present study shows the effect of the ISF on leptin concentrations in blood plasma and adipose tissue in mice during pregnancy. The ISF effect on thymus weight during pregnancy is also demonstrated. The leptin concentration in blood plasma and adipose tissue increased and remained high in the latter half of pregnancy. ISF treatment at the beginning of pregnancy significantly lowered the leptin concentration both in blood plasma and adipose tissue of pregnant mice. Thymus involution has been described previously in pregnant mice. ISF treatment compensated for the loss of thymus mass during the whole pregnancy in the ISF-treated mice. The treatment of pregnant mice with ISF did not affect pregnancy and litter size.

The alterations of immunological reactivity in heroin addicts and their normalization in patients maintained on methadone.

Drug addiction influences many physiological functions including reactions of the immune system. The higher occurence of infectious and other diseases in drug addicts has been explained by the depression of immunity due to the harmful effects of the drug. To test this assumption, we tested the proliferative responsiveness and cytokine production of PBL from a group of heroin addicts (N = 19), patients maintained on methadone (N = 15) and healthy controls (N=15). The results show that Con A-induced proliferation of PBL from heroin addicts was even enhanced in comparison with PBL from the control group. Similarly, production of IL-2, IL-10 and IFNgamma was higher in the group of heroin addicts than in healthy controls. The enhanced proliferation of PBL or the increased production of cytokines observed in heroin addicts was partially or completely normalized in the group of patients maintained on methadone. A significantly higher production of IL-6 was found in both unstimulated and stimulated PBL from heroin addicts and patients maintained on methadone, when compared with PBL from healthy controls. The results thus showed enhanced proliferative activity and increased production of various cytokines in heroin addicts and partial or complete adjustment of these alterations in patients maintained on methadone.

Corneal stromal cells selectively inhibit production of anti-inflammatory cytokines by activated T cells.

The eye has been described as an immunologically privileged site where immunity is purely expressed. It has been demonstrated that administration of antigen into the eye induces only a weak immune response. However, the anterior part of the eye represents an important protective barrier against pathogens and other harmful invaders from the outer environment. Therefore, effective immune mechanisms, which operate locally, need to be present there. Because the cornea has been shown to be a potent producer of various cytokines and other molecules with immunomodulatory properties, we investigated a possible regulatory role for the individual corneal cell types on cytokine production by activated T cells. Mouse spleen cells were stimulated with the T cell mitogen concanavalin A in the presence of either corneal explants or cells of corneal epithelial or endothelial cell lines and the production of T helper 1 (Th1) or Th2 cytokines was determined by enzyme-linked immunosorbent assay (ELISA) or reverse transcription-polymerase chain reaction (RT-PCR). We found that the cornea possesses the ability to inhibit, in a dose-dependent manner, production of the inhibitory and anti-inflammatory cytokines interleukin (IL)-4 and IL-10 by activated T cells. The production of cytokines associated with protective immunity [IL-2, IL-1beta, interferon (IFN)-gamma ] was not inhibited under the same conditions. Corneal explants deprived of epithelial and endothelial cells retained the ability to suppress production of anti-inflammatory cytokines. This suppression was mediated by a factor produced by corneal stromal cells and occurred at the level of cytokine gene expression. We suggest that by this mechanism the cornea can potentiate a local expression of protective immune reactions in the anterior segment of the eye.

Effects of boar seminal immunosuppressive fraction on production of cytokines by Concanavalin A-stimulated spleen cells and on proliferation of B lymphoma cell lines.

PROBLEM: The immunosuppressive fraction (ISF) of boar seminal vesicle fluid has recently been demonstrated to inhibit mitogen-stimulated proliferation of lymphocytes and antibody response to corpuscular and soluble antigens. The effects of ISF on in vitro and in vivo production of cytokines as well as its possible inhibitory effect on proliferation of B lymphoma cells remain to be elucidated. METHODS: The effect of ISF on proliferation of normal mouse spleen cells stimulated by Concanavalin A (Con A) and on mouse B lymphoma cells was measured by 3H-thymidine incorporation. Cytokines were determined in the supernatants of mouse spleen cells stimulated with Con A in the presence or absence of ISF by enzyme-linked immunosorbent assay (ELISA). In vivo cytokine production in the sera samples of mice treated with ISF and immunized with keyhole limpet hemocyanin (KLH) was followed by ELISA, too. RESULTS: We confirmed the inhibitory effect of ISF on Con A-stimulated lymphocyte proliferation. ISF affected cytokine production in the Con A-stimulated spleen cells: production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) was lowered, but production of IL-4, IL-6, and IL-10 was enhanced. Similarly, in the sera samples of mice immunized with keyhole limpet hemocyanin (KLH), IL-2 and IFN-gamma levels were decreased by ISF. ISF inhibited proliferation of Ag 8 and X 63-IL-2 B lymphoma cells as well. CONCLUSIONS: ISF inhibited production of T helper1 (Th1) cytokines (IL-2 and IFN-gamma) and enhanced production of Th2 cytokines (IL-4, IL-6, and IL-10). ISF seems to shift the Th1/Th2 pattern in favor of Th2. ISF exhibited an antiproliferative activity on mouse B lymphoma cells.

[Opioids and their immunomodulatory properties]. / Opiáty a jejich imunomodulacní vlastnosti.

Opiates have been recently used for suppression of the neuropathic pain or to relieve pain in patients with cancer diseases. However, opiates are also used by drug abusers to achieve feeling of euphoria. These drugs influence not only the nervous system but they can also modulate many other physiological functions including those of the immune system. Since opioid receptors have been found on the surface of cells of the immune system, two possible mechanisms of opiate actions have to be considered. The first one represents a direct action of the opiates through the opioid receptors on immune cells; the second mechanism is mediated by the nervous system. The immunomodulatory properties of the opiates have been demonstrated in numerous models. Especially the enhanced sensitivity to viral and bacterial infections, observed in drug abusers, is accounted to the side effects of opiates. Experimental animal models have shown even more complex actions of opiates, which can lead to suppression as well as to stimulation of individual immunological parameters. Although proliferation of lymphocytes tested in vitro after application of opiates in vivo is generally reduced, production of the pro-inflammatory cytokines and some functions of macrophages can be enhanced. Effects of opiate action depend on the experimental model used, the drug dose, way of drug application, time of testing and on the tested immunological parameter. This article summarizes recent knowledge of effects of opiates on the functions of cells of the immune system. It also refers global problems of exploitation of illegal drugs and the importance of methadone in the substitution treatment.

Augmented production of proinflammatory cytokines and accelerated allotransplantation reactions in heroin-treated mice.

Heroin treatment or abusive drug addiction influences many physiological functions, including the reactions of the immune system. Although suppression of various manifestations of the immune system after heroin (or morphine) administration has been reported, we show here that production of proinflammatory cytokines and nitric oxide (NO) was enhanced and allotransplantation reactions were accelerated significantly in heroin-treated recipients. Mice were treated by a subcutaneous administration of heroin (diacetylmorphine) given in one or repeated daily doses. The ability of spleen cells from treated mice to respond in vitro to alloantigens and to produce IL-2, IL-4, IL-10 and IFN-gamma, and the production of IL-1beta, IL-12 and NO by peritoneal macrophages, were tested. Within 2 h after heroin administration, proliferative responses to alloantigens and the production of IL-1beta, IFN-gamma, IL-12 and NO were enhanced significantly. In contrast, the production of anti-inflammatory cytokines IL-4 and IL-10 was at the same time rather decreased. As a consequence, skin allografts in heroin-treated mice were rejected more promptly than in untreated or vehicle-treated recipients. Similarly, the growth of allogeneic tumours induced by high doses of tumour cells was suppressed significantly in heroin-treated mice. The enhancing effects of heroin on the production of proinflammatory cytokines were antagonized by naltrexone, a specific inhibitor of classic opioid receptors. These results show that heroin treatment augments production of proinflammatory cytokines and accelerates allotransplantation reactions. The observations thus illustrate the complexity of the effects of heroin on the immune system and should be taken into account during medical treatment of opiate addicts and in the use of morphine to decrease pain in various clinical situations.

The effect of amphetamine sensitization on mouse immunoreactivity.

Recent studies indicate a role of the immune system in the behavioral effects of amphetamine in rodents. In the present study we attempted to find a connection between the behavioral changes induced by repeated, intermittent administration of amphetamine and some immunological consequences of sensitization to amphetamine in mice. Male Albino Swiss mice were treated repeatedly (for 5 days) with amphetamine (1 mg/kg, i.p.). On day 9, they received a challenge dose of amphetamine (1 mg/kg). Acute administration of amphetamine increased their locomotor activity by ca. 40%. In animals treated repeatedly with amphetamine, the challenge dose of the psychostimulant induced behavioral sensitization, i.e. the higher locomotor activation as compared with that after its first administration to mice. Immune functions were evaluated by the ability of splenocytes to proliferate and to produce cytokines such as interferon gamma (IFN-gamma), interleukin (IL)-4 and IL-10. Acute amphetamine administration significantly decreased, by ca. 30% and 25%, the proliferation of splenocytes in response to an optimal and a suboptimal dose of concanavalin A (Con A), respectively, and increased their ability to produce IL-4. Chronic intermittent treatment with amphetamine significantly decreased, by ca. 65% and 50%, the proliferative response of T cells to an optimal and a suboptimal dose of Con A, respectively, and diminished by 20% the metabolic activity of splenocytes. The above data showed that both acute and chronic amphetamine administration diminished some aspects of the cell-mediated immunity; nevertheless, immunosuppression was particularly evident in amphetamine-sensitized mice. Our findings seem to indicate possible importance of monitoring and correcting immune changes in the therapy of amphetamine addiction.

Reverse effect of indomethacin on the immunosuppressive activity of boar seminal immunosuppressive fraction.

The inhibitory activity of seminal immunosuppressive fraction (ISF) on mitogen-stimulated lymphocyte proliferation and on production of antibody to a soluble antigen was modified by indomethacin or monoclonal antibody to ISF. The ability of indomethacin or monoclonal antibody to ISF to reverse the ISF-induced inhibition of mitogen-stimulated lymphocyte proliferation was estimated by measuring bromodeoxyuridine incorporation into replicated DNA. Splenocytes from mice treated with indomethacin or monoclonal antibody to ISF prior to the application of ISF were tested. The ability of indomethacin or monoclonal antibody to ISF to reverse ISF-induced suppression of antibody production was estimated by measuring antibody titers by ELISA in the blood sera from mice immunized with keyhole limpet hemocyanin (KLH). These animals were treated with indomethacin or monoclonal antibody to ISF prior to the application of ISF. The results showed that both indomethacin and monoclonal antibody to ISF reversed the inhibitory effect of ISF on mitogen-stimulated lymphocyte proliferation as well as on antibody production.Recently, we have identified ISF as a complex of the major seminal glycoproteins PSP I and PSP II. PSP II is the part that is responsible for immunosuppressive properties of the complex. To learn whether the ISF immunosuppressive effect is associated with its protein or saccharide part, we examined the deglycosylated PSP II for its antiproliferative effect on mitogen-stimulated mouse lymphocytes. The results suggest that deglycosylation of PSP II did not affect its antiproliferative activity. This suggest that PSP II immunosuppressive properties are associated with the protein and not the saccharide part of the molecule.

Alloantigen-induced, T-cell-dependent production of nitric oxide by macrophages infiltrating skin allografts in mice.

The immunological rejection reaction occurring after organ or tissue transplantation is characterized by a strong infiltration of the graft by T cells and macrophages. Since the rejection reaction is highly specific, we tested the role of T cells in the activation of macrophages and in the induction of nitric oxide (NO) production during graft rejection. The rejection of both MHC and non-MHC antigen-disparate skin allografts was associated with a significantly increased production of NO in the graft. The kinetics of NO production after transplantation correlated with the rejection reaction and with the fate of the allograft. A significant reduction in NO production was found in immunologically hyporeactive mice treated with cyclosporine, and no specific production of NO was found in tolerated skin allografts from neonatally tolerant mice. The production of NO was completely suppressed in graft explants from mice with depleted CD4(+) cells, but remained at a normal level in skin allografts from mice treated with anti-CD8 monoclonal antibody. The treatment of recipients of fully allogeneic skin grafts with 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), a specific inhibitor of the inducible NO synthase, resulted in a significant prolongation of graft survival. The results thus show CD4(+) T-cell-dependent, alloantigen-induced production of NO by graft-infiltrating macrophages and the role of NO in the rejection reaction. We suggest that this pathway may represent one of the local effector mechanisms of graft rejection.

Evaluation of corneal graft rejection in a mouse model.

Corneal graft rejection presents clinically and in experimental models as opacification and is considered to be the result of endothelial cell dysfunction or loss. However, recovery from opacification can occur suggesting either (a) that new endothelial cells can regenerate if the original cells were lost, or (b) that sufficient numbers of original cells can regain function if the opacification was due to temporary dysfunction. In this perspective, previous experimental studies of allograft rejection plus some new data are reviewed to support the latter mechanism.

Immunosuppressive effects of vermiculine in vitro and in allotransplantation system in vivo.

Vermiculine, a macrocyclic aglycosidic dilactone isolated from Penicillium vermiculatum, has been shown to have immunomodulatory properties. Here, we tested the effects of vermiculine on selected parameters of cell-mediated immunity in vitro and on skin allograft survival in vivo. Vermiculine inhibited in a dose-dependent manner the proliferation of mouse spleen cells stimulated with Concanavalin A ((Con A), i.e. T-cell mitogen), bacterial lipopolysaccharide ((LPS), B-cell mitogen) or with irradiated allogeneic cells. In addition, vermiculine dose-dependently inhibited the production of Thl (IL-2, IFN-gamma) and Th2 (IL-4, IL-10) cytokines and suppressed the production of nitric oxide (NO) by activated macrophages. When compared with cyclosporine (CsA), vermiculine was less inhibitory for IL-2 gene expression and IL-2 synthesis, comparably suppressive on IL-10 production and even more inhibitory for NO synthesis. These observations suggest that vermiculine and CsA inhibit immune reactions by different mechanisms. Treatment of graft recipients with vermiculine or CsA prolonged survival of skin allografts in a mouse model. The combination of both drugs enhanced the survival of allografts significantly more than either drug alone. The results thus suggest that vermiculine is a potential immunosuppressive drug acting by a mechanism distinct from that of CsA, and thus it may be used alone or in combination with other drugs for immunoregulatory purposes.

Kinetics of leukocyte and myeloid cell traffic in the murine corneal allograft response.

BACKGROUND: Little information exists on the trafficking of myeloid and lymphoid cells between the transplanted cornea and the secondary lymphoid tissue. This study reports on changes in the cornea and the draining lymph node (DLN) from the time of graft emplacement. METHODS: Using a mouse corneal graft model (C57BL/10Sn to BALB/c), eyes and submandibular DLN were examined by immunohistochemistry and three-color flow cytometry for evidence of T cell activation and dendritic cell (DC) conditioning (up-regulation of costimulatory molecules) at various times (15 min to 24 days; n=4 for each time). RESULTS: In the DLN, early (2 hr) DC conditioning was sustained throughout allograft rejection whereas a remarkable drop in percentage of activated CD4+ and CD8+ T cells (P <0.001) was followed by a biphasic rise in activated CD4+ and, to a lesser extent, CD8+ T cells (24 hr, P <0.001 and 6 days, P <0.01). CD11b+ and MOMA-2+ macrophages, MHC Class II+ cells, CD86+ DC, and neutrophils were the earliest cells infiltrating the cornea (at 24 hr), whereas T cells appeared after 2 days, with CD4+ T cells being confined largely to the graft recipient border. CONCLUSIONS: Immediate and rapid changes in T cell and DC populations in the DLN correlate with the type of cellular infiltration in the corneal graft. The data are consistent with a model in which CD4+ T cell help for CD8+ cytotoxic T cells could be provided by sequential two-way activation of T cells and DC in the DLN. The majority of cells infiltrating the graft were macrophages and neutrophils, with fewer DC and T cells.

Prolonged desipramine treatment increases the production of interleukin-10, an anti-inflammatory cytokine, in C57BL/6 mice subjected to the chronic mild stress model of depression.

BACKGROUND: Depression is associated with activation of the inflammatory response system (IRS). In humans, antidepressants significantly increase the production of interleukin-10 (IL-10), a negative immunoregulatory cytokine. The aims of the present study were to examine the effects of desipramine, a tricyclic antidepressant, on the IRS in C57BL/6 mice with and without exposure to chronic mild stress (CMS). METHODS: We examined the effects of desipramine on the cytotoxic activity of natural killer (NK) cells, the proliferative responses of lymphocytes after stimulation with IL-1, IL-2, lipopolysaccharide (LPS), concanavaline-A (Con-A), phytohaemagglutinin-P (PHA), pokeweed mitogen (PWM), and anti-CD3 monoclonal antibodies, the production of IL-2, IL-4, IL-10 and interferon-gamma (IFNgamma) by T lymphocytes and the ability of B cells to proliferate after stimulation by lipopolysaccharide (LPS). RESULTS: Prolonged treatment of C57BL/6 mice subjected to CMS with desipramine increases the ability of T cells to produce IL-10 and the ability of B cells to proliferate after stimulation with LPS; and significantly decreases the cytotoxic activity of NK cells and the proliferative responses of lymphocytes after stimulation with Con-A, PHA and anti-CD3 monoclonal antibodies. Repeated administration of desipramine to non-stressed mice increases the activity of T lymphocytes, lowers that of B lymphocytes, increases the production of IL-10 by T cells and has no significant effect on the activity of NK cells. CONCLUSION: Prolonged desipramine treatment of stressed and non-stressed C57BL/6 mice induces an increase in the production of IL-10, an anti-inflammatory cytokine.

Immunoreactivity in kainate model of epilepsy.

Seizure-related changes in function of the peripheral immune system, especially in its cell component are poorly recognized. In the present study, we examined the effect of seizures induced by intraperitoneal injection of kainate to mice and rats on weight of central and secondary immunological organs and metabolic activity of splenocytes (MTT test). In kainate-injected mice the production of cytokines: interleukin 2 (IL-2) and IL-10 was also estimated. Seventy two hours after kainate administration, the mice and rats showed a marked decrease in the thymus weight by 36% and 50%, respectively, whereas the spleen weight tended to decrease in rats only. Splenocytes of kainate-injected mice and rats showed significant increase in metabolic activity. The ability of splenocytes of kainate-injected mice to produce IL-2 and IL-10 was reduced but only the former effect reached statistical significance. The results suggest a decrease in T helper-cell dependent immunoreactivity and enhanced phagocytic activity of macrophages in kainate-treated rodents.