BCG masking phenomena might depend on the species of Mycobacterium.

This study investigated BCG masking dependency on the species of Mycobacterium through the immune response to the mycobacterial region of deletion 1 (RD-1) associated growth affecting proteins (GEP).To evaluate the effects of GEP, 8-week old female BALB/c mice were immunized with either the wild type Mycobacterium bovis (MBGEP) or the ATCC Mycobacterium avium subsp. avium (MAGEP) strain and then subjected to further exposure with Mycobacterium terrae or M. avium sub. avium. Mice immunized with MAGEP and those mice further exposed to M. avium subsp. avium had increased granulocytes (GRA) and monocytes to lymphocytes rate (MLR) compared to control mice. Immunization of mice with GEP induced an antibody response one month after primary immunization, as observed by cross-reactivity. Our findings suggest that MAGEP is related to a latent hypersensitivity reaction and an increased risk of mycobacterial infection susceptibility. According to the results of the present study, previous sensitization with NTM antigens results in varying immune reactions after contact with different NTM argued that masking phenomena may be dependent on the species of Mycobacterium.

Doxorubicin uptake in ascitic lymphoma model: resistance or curability is governed by tumor cell density and prolonged drug retention.

Background/Aims: Chemotherapy resistance of malignancies is a universal phenomenon which unfavorably affects therapeutic results. Genetic adaptations as well as epigenetic factors can play an important role in the development of multidrug resistance. Cytotoxic drug content in plasma of cancer patients is known to variate up to one hundred-fold regardless of the same dose injected per m2 body surface. The relationship between plasma concentrations, tissue uptake, and chemotherapy response is not completely understood. The main objective of this study was to investigate how the identical dose of Doxorubicin (Dox) can result in a different therapeutic response pattern depending on tumor size. Study Design: The study was performed on ascitic EL4 lymphoma in an exponential growth phase focusing on the rapidly changing tumor susceptibility to the Dox treatment. Well distinguishable tumor response patterns (curability, remission-relapse, resistance) were selected to unveil Dox intratumoral uptake and drug tissue persistence. Intratumoral Dox content within peritoneal cavity (PerC) in conjunction with systemic toxicity and plasma pharmacokinetics, were monitored at several time points following Dox injection in tumor bearing mice (TBM) with differing patterns of response. Results: Following intraperitoneal (i.p.) transplantation of 5x104 EL4 lymphoma cells rapid exponential proliferation with ascites volume and animal mass increase resulted in median survival of 14.5 days. The increase in tumor cell mass in PerC between day 3 and day 9 was 112.5-fold (0.2±0.03 mg vs 22.5±0.31 mg respectively). However, tumors at this time interval (day 3 to day 9 post-transplantation) were relatively small and constituted less than 0.05% of animal weight. An identical dose of Dox (15 mg/kg) injected intravenously (i.v.) on Day 3 lead to a cure whereas a TBM injected on day 9 exhibited resistance with a median survival time no different from the untreated TBM control. Injection of Dox resulted in noticeable differences of cellular uptake in PerC between all three groups of TBM ("cure", relapse", "resistance"). Larger tumors were consistently taking up less Dox 60 min after the 15 mg/kg i.v. bolus injection. Higher initial uptake resulted also in longer retention of drug in PerC cells. The area under the concentration curve in PerC cells AUC0-10d was 8.2±0.57 µg/g x h, 4.6±0.27 µg/g x h and 1.6±0.02 µg/g x h in "cure", "relapse" and "resistance" TBM respectively (p<0.05 "relapse" vs "cure" and p<0.001 "resistance" vs "cure"). No differences in plasma Dox pharmacokinetics or systemic hematological effects were observed in TBM following a single i.v. Dox push. Hematologic nadir was tested on day 2 and subsequent hematologic recovery was evaluated on day 10 following Dox administration. Hematologic recovery on day 10 coincided with complete drug efflux from PerC and rising tumor cell numbers in PerC of "relapse" TBM. Myelosuppression and hematological recovery patterns were identical in all surviving animal groups regardless of the tumor size on the day of Dox injection. Conclusions: Within a few days of exponential tumor growth, an identical dose of Dox produced dramatically different responses in the TBM with increasing resistance. Systemic toxicity and plasma pharmacokinetics were indistinguishable between all TBM groups. Initial uptake in tumor cells was found to be consistently lower in larger tumors. Drug uptake in tumor cells was regulated locally - a phenomenon known as inoculum effect in vitro. The duration of drug retention in cells was directly related to initial cellular uptake. The magnitude of Dox cellular retention could potentially play a role in determining tumor remission and relapse.

Intratumoral Accumulation and Clonal Expansion May Not Be Decisive for Rejection of Allogeneic Tumors by CD8+ T-Lymphocytes.

BACKGROUND: The aim of this study was to analyze the spatial distribution and proliferation of adoptively transferred CD8+ T-lymphocytes sensitized against allogeneic tumors. MATERIALS AND METHODS: Transgenic ß-actin-luc mice that express luciferase were sensitized against allogeneic SL2 lymphoma. CD8+ T-lymphocytes from these mice were transferred to lymphocyte-deficient, recombination activating gene-deficient (Rag-/-) mice bearing SL2 tumors and were tracked using bioluminescence imaging. RESULTS: Two out of six Rag-/- mice rejected their tumors. There were no apparent differences in spatial distribution and proliferative intensity of adoptively-transferred CD8+ T-lymphocytes between the two Rag-/- mice that rejected allogeneic SL2 tumors and the four Rag-/- mice that did not. CONCLUSION: The pattern of distribution in the mouse body and proliferative intensity of CD8+ T-lymphocytes do not seem to be decisive factors influencing allogeneic tumor rejection.

Mycobacteria produce proteins involved in biofilm formation and growth-affecting processes.

The aim of this study was to determine the effect of mycobacterial proteins on mycobacterial biofilm formation and growth processes. We separated growth-affecting proteins (GEPs) from wild type of Mycobacterium bovis and ATCC strain of Mycobacterium avium subsp. avium. Our results showed that these mycobacteria-secreted GEPs are involved in biofilm formation, growth stimulatory, and inhibitory processes. Our findings suggest that GEP stimulated M. avium subsp. avium growth in vitro. Stimulation process was observed in mycobacteria affected with GEP extracted from M. avium subsp. avium. We found that both GEPs inhibited the growth of the M. bovis. Optical density measurement and visual analysis confirm that GEP plays an important role in biofilm formation process. Most of M. bovis GEP are associated with the type VII secretion and general secretion pathways. Our results contribute to a better understanding of the mechanisms underlying mycobacterial biofilm formation and growth-affecting processes and better characterization of mycobacterial proteins and their functions. It is noteworthy that this finding represents the first demonstration of GEP-mediated growth effects on a solid and liquid medium.

Parvovirus B19 infection modulates the levels of cytokines in the plasma of rheumatoid arthritis patients.

BACKGROUND: Parvovirus B19 (B19V) infection is associated with various autoimmune diseases. We investigated the levels of pro-inflammatory (IFNᵧ, TNFα, IL-2, IL-12) and anti-inflammatory (IL-4, IL-10) cytokines in the plasma of B19V DNA positive (B19+) and negative (B19-) rheumatoid arthritis (RA) patients in comparison with the control group (healthy persons). METHODS: Blood samples were collected from 118 patients with RA and 49 healthy voluntaries. B19V sequence was determined in whole blood and cell-free plasma DNA by nested PCR. The levels of cytokines in the plasma and cell culture medium from Concanavalin A (ConA) or B19V VP1 protein stimulated PBMC were determined by ELISA. RESULTS: The levels of IL-4, IL-10, IL-12, IL-2 and TNFα were higher in plasma of RA patients in comparison with control persons. B19+ controls and RA patients had lower levels of IFNᵧ in comparison with B19- controls and RA patients. Within RA patients the plasma levels of IFNᵧ were lower in patients with low RA disease activity or remission. Plasma level of IL-4 was increased and IL-10 level was decreased in B19+ RA patients in comparison with B19- RA patients and did not differ between B19+ and B19- controls. B19V infection did not affect plasma levels of IL-12, IL-2, and TNFα. ConA and B19 VP1 protein stimulated PBMC from RA patients produced less IFNᵧ than stimulated PBMC from the healthy controls. CONCLUSIONS: B19V infection could differently modulate the amount of cytokines in the plasma of healthy persons and RA patients. Decreased production of IFNᵧ and raised level of plasma IL-4 in RA patients could lower antiviral clearance.

Increased Numbers of CD4+CD25+ and CD8+CD25+ T-Cells in Peripheral Blood of Patients with Rheumatoid Arthritis with Parvovirus B19 Infection.

AIM: To investigate T-cell subpopulations in peripheral blood of human parvovirus B19 DNA-positive (B19+) and -negative (B19-) patients with rheumatoid arthritis (RA) and healthy persons. PATIENTS AND METHODS: Blood samples were collected from 115 patients with RA and 47 healthy volunteers; 27 patients with RA and nine controls were B19+ Cluster of differentiation (CD) 4, 8, 25 and 45RA were analyzed on blood cells. CD25 expression on CD4+CD45RA+, CD4+CD45RA-, CD8+CD45RA+, CD8+CD45RA- subsets were analyzed by flow cytometry. RESULTS: The percentage of CD25low and CD25hi cells was increased on CD4+CD45RA+, CD4+CD45RA- T-cells and the percentage of CD25+ cells was increased on CD8+CD45RA+, CD8+CD45RA- T-cells of B19+ patients with RA in comparison with B19- patients and controls. CONCLUSION: Raised levels of CD4 and CD8 regulatory T-cells in B19+ RA patients could cause down-regulation of antiviral clearance mechanisms and lead to activation of persistent human parvovirus B19 infection in patients with RA.

Hospital Exemption for Advanced Therapy Medicinal Products: Issue in Application in the European Union Member States.

Regulation (EC) 1394/2007 of the European Parliament and the Council on advanced therapy medicinal products and amending Directive 2001/83/EC and Regulation (EC) No 726/2004 allowed the use of non - authorized advanced therapy medicinal products under the certain circumstances. This socalled hospital exemption rule needs to be applied in the each Member State of the European Union individually and for this purpose Member States should provide national procedures and control measures. The aim of this article is to clear up the criteria for hospital exemption listed in Regulation (EC) 1394/2007 and to contrast the difference in implementing hospital exemption rule into national legal regimes on examples of the United Kingdom, Lithuania and Poland.

Frequency and significance of parvovirus B19 infection in patients with rheumatoid arthritis.

The present study aims to clarify the possible involvement of parvovirus B19 (B19V) infection in rheumatoid arthritis (RA) pathogenesis by investigating the presence of B19V infection markers (genomic sequences and virus-specific antibodies) in association with the level of cytokines and RA clinical activity and aggressiveness. A total of 118 RA patients and 49 age- and sex-matched healthy volunteers were enrolled in the study. Nested PCR was used to detect B19V sequences in whole blood and cell-free plasma DNA, ELISA to detect virus-specific antibodies and cytokine levels in plasma and recomLine dot blot assay for antibodies to separate B19V antigens. The detection frequency of B19V DNA was higher in patients with RA (25.4 %) in comparison with healthy persons (18.4 %). B19V DNA in cell-free plasma (B19+p) was detected significantly often in RA patients in comparison with healthy controls (13.6 vs 2 %; P=0.0002). RA B19+p patients had higher disease activity and aggressiveness, decreased haemoglobin and increased erythrocyte sedimentation rates. IL-6 plasma levels were significantly higher in RA patients than in controls. Within the RA patients' group the IL-6 level was significantly increased in B19+p patients with disease activity scores of DAS28>5.2, high C-reactive protein and low haemoglobin. Contrary to the healthy controls, the majority of RA B19+p patients did not have antibodies to VP-1S (VP1u) and VP-N (N-terminal half of structural proteins VP1 and VP2), which correspond to the epitopes of neutralizing antibodies. These results indicate that B19V infection at least in some patients is involved in RA pathogenesis.

Reduction in Proportion of Senescent CD8+ T Lymphocytes During Chemotherapy of Children with Acute Lymphoblastic Leukemia.

AIM: To evaluate quantitative changes in B, NK and T lymphocyte subsets in peripheral blood of children with acute lymphoblastic leukemia (ALL) undergoing chemotherapy. PATIENTS AND METHODS: Children with ALL were treated according to NOPHO ALL 2008 protocol. Levels of B lymphocytes (CD19+), NK cells (CD3-CD56+) and subsets of T lymphocytes (CD3+CD4+, CD4+CD25+Foxp3+, CD3+CD8+, CD3+CD8+CD57+, CD3+CD8+CD57-) in peripheral blood were analyzed by flow cytometry prior and during treatment with cytotoxic drugs. RESULTS: Immunological analyses were performed in 25 children with ALL. Levels of B and NK lymphocytes decreased continuously during chemotherapy. In contrast, levels of most T lymphocyte subsets decreased only transiently and returned to pretreatment levels by days 78 to 85. The only T lymphocyte subset that did not return to the pretreatment level contained senescent CD3+CD8+CD57+ lymphocytes. CONCLUSION: Immunomodulating action of chemotherapy in children with ALL results in reduction of proportion of senescent CD8+ T lymphocytes.

Skeletal Muscle-Derived Stem/Progenitor Cells: A Potential Strategy for the Treatment of Acute Kidney Injury.

Skeletal muscle-derived stem/progenitor cells (MDSPCs) have been thoroughly investigated and already used in preclinical studies. However, therapeutic potential of MDSPCs isolated using preplate isolation technique for acute kidney injury (AKI) has not been evaluated. We aimed to characterize rat MDSPCs, compare them with bone marrow mesenchymal stem cells (BM-MSCs), and evaluate the feasibility of MDSPCs therapy for gentamicin-induced AKI in rats. We have isolated and characterized rat MDSPCs and BM-MSCs. Characteristics of rat BM-MSCs and MDSPCs were assessed by population doubling time, flow cytometry, immunofluorescence staining, RT-PCR, and multipotent differentiation capacity. Gentamicin-induced AKI model in rat was used to examine MDSPCs therapeutic effect. Physiological and histological kidney parameters were determined. MDSPCs exhibited similar immunophenotype, stem cell gene expression, and multilineage differentiation capacities as BM-MSCs, but they demonstrated higher proliferation rate. Single intravenous MDSPCs injection accelerated functional and morphological kidney recovery, as reflected by significantly lower serum creatinine levels, renal injury score, higher urinary creatinine, and GFR levels. PKH-26-labeled MDSPCs were identified within renal cortex 1 and 2 weeks after cell administration, indicating MDSPCs capacity to migrate and populate renal tissue. In conclusion, MDSPCs are capable of mediating functional and histological kidney recovery and can be considered as potential strategy for AKI treatment.

Bioluminescence Imaging of Adoptively Transferred Lymphocytes During Allogeneic Tumor Rejection.

AIM: The aim of the present study was to analyze the survival, spatial distribution and proliferation of adoptively transferred lymphocytes in allogeneic tumor rejection. MATERIALS AND METHODS: Transgenic ß-actin-luc mice that express luciferase were sensitized against SL2 tumors and were used as lymphocyte donors to study the anti-tumor effect in SL2 tumor-bearing lymphocyte-deficient RAG(-/-) mice. Whole-body bioluminescence images of recipient mice were obtained to track the adoptively transferred lymphocytes. Proliferation of lymphocytes was estimated by quantification of photon emission. RESULTS: T lymphocytes sensitized against allogeneic SL2 tumors cured the majority of SL2 tumor-bearing RAG(-/-) mice. Bioluminescence imaging showed that transferred T lymphocytes survived in the spleen and lymph nodes. Tumor rejection was associated with lymphocyte proliferation and migration to the tumor site. CONCLUSION: Sensitized T lymphocytes from transgenic ß-actin-luc mice reject allogeneic SL2 tumors in RAG(-/-) mice and can be tracked in vivo using bioluminescence imaging.

Melatonin inhibits granulocyte adhesion to ICAM via MT3/QR2 and MT2 receptors.

Neutrophils are cells of the innate immune system that first respond and arrive to the site of infection. Melatonin modulates acute inflammatory responses by interfering with leukocyte recruitment. It is known that melatonin modulates granulocyte migration though the endothelial layer thereby acting on the endothelial cell. Here we investigated whether melatonin could modulate granulocyte infiltration by acting directly on granulocytes. Granulocyte infiltration into the peritoneal cavity was investigated in mice kept at normal light/dark conditions and mice kept under constant lighting. To induce migration of neutrophils from the blood into the injury site via the endothelial layer, a bacterial product N-formyl-l-methionyl- l-leucyl- l-phenylalanine (fMLP) was injected into the peritoneal cavity. We found that the number of infiltrated granulocytes during the dark time was lower than that during the light time. It did not depend on circadian time. Moreover, the expression of an adhesion molecule, CD18, on granulocytes, was also lower during the dark time as compared with the light time. We have found that melatonin inhibited fMLP-induced CD18 up-regulation. Importantly, melatonin also inhibited the integrin-mediated granulocyte adhesion to intercellular adhesion molecule-coated plates. This study additionally showed that melatonin receptors MT2 and MT3/quinone reductase 2 (QR2) are expressed on granulocytes. Interestingly, melatonin increases the expression of its MT3/QR2 receptor. The fMLP-mediated CD18 up-regulation was inhibited by melatonin via MT2 receptor and the integrin-mediated granulocyte adhesion was inhibited by melatonin via MT3/QR2 and MT2 receptors. In conclusion, we show that melatonin suppresses granulocyte migration via endothelium by acting directly on granulocytes.

ß-Glucan from Saccharomyces cerevisiae Induces IFN-γ Production In Vivo in BALB/c Mice.

AIM: ß-Glucan is one of the most abundant polymers in nature and has been established as an immunomodulator. This compound has notable physiological effects on mammalian immune systems, including anti-tumor and anti-infective activities and can activate the immune response. It is considered that the immune-stimulating activities of ß-glucan can depend on physicochemical parameters, such as molecular size. Saccharomyces cerevisiae, also known as baker's yeast, is a frequently used source of ß-glucan. The aim of the experiments was to investigate how different Saccharomyces cerevisiae ß-glucan preparations with different molecular size affect interferon-gamma (IFN-γ) production in BALB/c mice. MATERIALS AND METHODS: In vivo and in vitro BALB/c mouse models were used for the investigations. Different ß-glucan preparations were orally administrated in the in vivo experiments. IFN-γ production in BALB/c mice was analyzed by enzyme-linked immunosorbent assay and measuring interferon-γ RNA concentration. RESULTS: The results showed that orally-administered ß-glucan from S. cerevisiae enhanced IFN-γ production in BALB/c mice in the in vivo model, but not by mouse leukocytes in vitro. Moreover, water-soluble ß-glucan enhanced IFN-γ production more effectively than did particulate ß-glucan. CONCLUSION: IFN-γ plays an important role in immunity against viral and bacterial infections. Our experiments have shown that ß-glucan preparations enhance IFN-γ production in BALB/c mice and can be potentially used for immune system stimulation in mammals. Current results may be used to develop soluble ß-glucan nutritional supplements.

Influence of circadian time and lighting conditions on expression of melatonin receptors 1 and 2 in murine lymphocytes.

AIM: To investigate the expression of membrane melatonin receptors in murine thymocytes, CD4(+) T-cells, bone marrow cells and B-cells according to melatonin concentration in the blood. MATERIALS AND METHODS: The levels of mRNA of melatonin receptors were investigated in the cells isolated during the day or during the night, corresponding to low and high melatonin concentrations in the blood. RESULTS: Low levels of Mtnr1 and Mtnr2 transcripts were detected in thymocytes and splenic B-cells. The expression of membranous melatonin receptors in B-cells corresponds to melatonin concentration in the blood. CONCLUSION: The expression of Mtnr1 and Mtnr2 in murine lymphocytes is very weak. Melatonin may be involved in regulation of the expression of Mtnr1 and Mtnr2 in murine B-cells.

The expression of MTNR3 and nuclear receptors in murine leucocytes.

AIM: The aim of this study was to investigate the expression of melatonin receptor MTNR3 and nuclear receptors in murine lymphocytes and their dependence on lighting conditions and circadian time. MATERIALS AND METHODS: The mRNA levels of melatonin receptors were investigated in cells isolated from thymus, spleen, lymph nodes and bone marrow during the day or during the night. RESULTS: The expression of MTNR3 in B-cells and bone marrow cells was much higher than in thymocytes and T-cells. Retinoic acid receptor-related orphan receptor A (Rora) was found mostly in thymocytes and cluster of differentiation 4 positive (Cd4(+)) T cells. Rorc was detected in thymocytes; its expression in peripheral T-cells was very low. Rorb was not detected in lymphocytes. MTNR3 transcripts in B-cells and Rorc transcripts in thymocytes increased during the day and decreased during the night. CONCLUSION: Circadian time and lighting could be involved in the regulation of the expression of melatonin receptors MTNR3 and Rorc.

The change in the amount of immunoglobulins as a response to stress experienced by soldiers on a peacekeeping mission.

PURPOSE: Recent studies have demonstrated various changes in systemic and mucosal immunity in people undergoing psychological stress. This study was designated for an assay of associations between the stress experienced by Lithuanian soldiers as a response to changed job conditions (deployment to Afghanistan) and level of immunoglobulins. Salivary and sera immunoglobulin concentrations were assessed and compared before and after the military mission; the associations between the deployment-related stress and the immunoglobulin level were examined. METHODS: Special questionnaires covering state of health and strain experienced were used. Quantitative detection of immunoglobulins was performed by sandwich ELISA. RESULTS: Comparison of the medians at three time points (before, after the deployment and 1 year after the mission) showed an increased level of salivary secretory immunoglobulin A (S-IgA) in association with deployment. Chi-square test of independence indicated statistically significant relationship between the stress and S-IgA amount. Correlation analysis using different health control methods revealed masked fear of soldiers to be expelled from the military service. CONCLUSIONS: The results indicated that salivary S-IgA is the most sensitive representative of mucosal immunity system to psychological stress related to changed job conditions in military service.

Leukocytosis as a prognostic marker in the development of fetal inflammatory response syndrome.

OBJECTIVE: To identify and evaluate the correlation between leukocyte count in maternal blood and the risk of developing fetal inflammatory response syndrome (FIRS). PATIENTS AND METHODS: The study involved 158 infants born at 22 - 34 weeks of gestation and their mothers. Umbilical cord blood cytokines were evaluated in immunoassay tests and maternal blood was tested for the leukocyte formula. RESULTS: The period of gestation was significantly shorter in the FIRS group compared to the control group (29.5±3.1 vs. 32.2±2.4 weeks, p<0.001). Gestational age was ≤30 weeks for 53.8% of the newborns in the FIRS group and 15.8% of the newborns in the control group (p<0.001). The number of leukocytes in maternal blood before and during labor was significantly higher in the FIRS group than in the control group (p=0.034 and 0.004, respectively). The study determined the correlation between the total leukocyte count in maternal blood and IL-6 concentration during labor (p=0.05) and tumor necrosis factor (TNF-α) concentration in umbilical cord blood before and during labor (p=0.02 and 0.007, respectively). CONCLUSION: Leukocytosis in the FIRS group was significantly higher than in the control group before and during labor. According to our data, one of the possible indicators of intrauterine infection could be the number of leukocytes in maternal blood.

Purification and partial characterization of a novel ß-1,3-endoglucanase from Streptomyces rutgersensis.

A ß-1,3-endoglucanase produced by Streptomyces rutgersensis was purified to a homogeneity by the fractional precipitation with ammonium sulfate, ion exchange chromatography on Q-Sepharose and hydrophobic chromatography on Butyl Sepharose. A typical procedure provided 11.74-fold purification with 12.53 % yield. SDSPAGE of the purified protein showed one protein band. The exact molecular mass of the enzyme obtained by mass spectrometry was 41.25 kDa; the isoelectric point was between pH 4.2­4.4. The optimal ß-glucanase catalytic activity was at pH 7 and 50 °C. An enzyme was only active toward glucose polymers containing ß-1,3 linkages and hydrolyzed Saccharomyces cerevisiae cell wall ß-glucan in an endo-like way: reaction products were different molecular size ß-glucans, which were larger than glucose.

Melatonin secretion in children with epilepsy.

This study examined melatonin (MLT) system in children with epilepsy. Diurnal patterns of salivary MLT, urinary metabolite 6-sulphatoxymelatonin, core body temperature, pulse and blood pressure were measured in 51 children with epilepsy (6.6-17.9 years) and 29 comparison children (5.5-17.3 years). The children with epilepsy preserved MLT and other circadian rhythms. In nine children with epilepsy (17.6%), peak salivary MLT concentrations were very high. There were no associations between MLT secretion/excretion parameters (diurnal profile, peak nocturnal concentrations, area under the time curve, duration of elevated concentrations, acrophase) and seizure characteristics (time, type of seizures, antiepileptic medications). The study observations are important for understanding of the MLT system in epilepsy and for exploring the potential for seizure treatment with melatonin.

Expanded effector memory T-lymphocytes in DBA/2 mice do not inhibit the growth of SL2 tumours.

BACKGROUND: The aim of this study was to analyse changes in levels of memory T-lymphocytes during growth of SL2 tumours in DBA/2 mice and to evaluate whether these lymphocytes may have an inhibitory effect on tumour growth. MATERIALS AND METHODS: Percentages of naïve (CD8+CD44lowCD62L+), central memory (CD8+CD44high CD62L+) and effector memory (CD8+CD44highCD62L-) lymphocytes in the CD8+ subset in peripheral blood, spleen and lymph nodes of tumour-bearing and control mice were analysed by flow cytometry. RESULTS: The percentage of effector memory lymphocytes in the CD8+ subset increased during growth of tumours, whereas that of naïve CD8+ lymphocytes decreased. No correlation between the levels of effector memory lymphocytes in peripheral blood and the mass of tumours was found. CONCLUSION: SL2 tumours induce expansion of effector memory lymphocytes in DBA/2 mice. However, expanded effector memory lymphocytes do not inhibit the growth of tumours.