Immunophenotyping analysis of peripheral blood, splenic, and thymic lymphocytes in male and female rats

Sex-dependent responses to high concentration of binge ethanol in spleen of adolescent F344 rats

BACKGROUND

We previously reported that binge ethanol induces atrophy of the spleen, a key immune organ, in adolescent male F344 rats. Because there are significant sex effects in immune function, we investigated whether binge ethanol exerts sex-dependent effects on the spleen, including producing splenic atrophy.

METHODS

We gave F344 rats ethanol (4.8 g/kg/day; 52% w/v; i.g.) on postnatal days [PND] 36 ~ 38 and sacrificed them on PND 39 for spleen collection. We performed immunophenotyping analysis of splenic cells and examined the expression of 158 genes related to alcohol metabolism, epigenetic modification, and immune regulation in the spleens of adolescent (PND 39) male and female rats.

RESULTS

Following a 3-day ethanol exposure, a loss of body weight, and absolute and relative spleen weight, was seen only in male adolescent rats. Ethanol altered the relative proportions of lymphocyte subtypes in both sexes with different patterns. We also found that 3-day ethanol exposure induced sex-dependent gene expression changes in spleen. Among the 158 genes studied, the expression of only three genes was significantly increased in female rats. However, the expression of 30 genes was significantly increased/decreased in male rats. Female rats had greater expression of alcohol metabolizing enzyme genes in the spleen under physiological conditions and when stimulated by binge ethanol. The genes are involved in epigenetic modification were differentially expressed in a sex-dependent manner.

CONCLUSION

We found that male adolescent rats were more sensitive to binge ethanol than female rats. Differential expression of the genes related to alcohol metabolism and epigenetic modification (of DNA methyltransferase and histone deacetylases) between the sexes could account for the observed sex-dependent responses to binge ethanol in adolescent rats.

Ritonavir nanosuspensions prepared by microfluidization with enhanced solubility and desirable immunological properties

The objective of this study was to develop ritonavir (RTV) nanosuspensions (NSs) by microfluidization method. Particle size (PS) measurements were performed by photon correlation spectroscopy. Amorphous properties of the particles were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dissolution studies were conducted in fed state simulated intestinal fluid (FeSSIF) medium. The flow cytometry was utilized to determine the lymphocyte sub-groups and immune response of NSs. RTV NSs were obtained with 400-500 nm PS. The crystal properties of RTV remain unchanged. The solubility of NS was enhanced five times. 57% and 18% of RTV were dissolved in FeSSIF medium for NSs and coarse powder. According to immunological studies, the prepared NSs did not significantly alter the ratio of CD4⁺/CD8⁺. Therefore, NSs may be a beneficial approach for the oral administration of RTV.

Preclinical assessment of thrombin-preconditioned human Wharton's jelly-derived mesenchymal stem cells for neonatal hypoxic-ischaemic brain injury

Hypoxic-ischaemic encephalopathy (HIE) is a type of brain injury affecting approximately 1 million newborn babies per year worldwide, the only treatment for which is therapeutic hypothermia. Thrombin-preconditioned mesenchymal stem cells (MSCs) exert neuroprotective effects by enriching cargo contents and boosting exosome biogenesis, thus showing promise as a new therapeutic strategy for HIE. This study was conducted to evaluate the tissue distribution and potential toxicity of thrombin-preconditioned human Wharton's jelly-derived mesenchymal stem cells (th-hWJMSCs) in animal models before the initiation of clinical trials. We investigated the biodistribution, tumorigenicity and general toxicity of th-hWJMSCs. MSCs were administered the maximum feasible dose (1 × 105 cells/10 µL/head) once, or at lower doses into the cerebral ventricle. To support the clinical use of th-hWJMSCs for treating brain injury, preclinical safety studies were conducted in newborn Sprague-Dawley rats and BALB/c nude mice. In addition, growth parameters were evaluated to assess the impact of th-hWJMSCs on the growth of newborn babies. Our results suggest that th-hWJMSCs are non-toxic and non-tumorigenic in rodent models, survive for up to 7 days in the brain and hold potential for HIE therapy.

Immunological comparison of pregnant Dahl salt-sensitive and Sprague-Dawley rats commonly used to model characteristics of preeclampsia

The pregnant Dahl salt-sensitive (S) rat is an established preclinical model of superimposed spontaneous preeclampsia characterized by exacerbated hypertension, increased urinary protein excretion, and increased fetal demise. Because of the underlying immune system dysfunction present in preeclamptic pregnancies in humans, we hypothesized that the pregnant Dahl S rat would also have an altered immune status. Immune system activation was assessed during late pregnancy in the Dahl S model and compared with healthy pregnant Sprague-Dawley (SD) rats subjected to either a sham procedure or a procedure to reduce uterine perfusion pressure (RUPP). Circulating immunoglobulin and cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA) and Milliplex bead assay, respectively, and percentages of circulating, splenic, and placental immune cells were determined using flow cytometry. The pregnant Dahl S rat exhibited an increase in CD4+ T cells, and specifically TNFα+CD4+ T cells, in the spleen compared with virgin Dahl S rats. The Dahl also had increased neutrophils and decreased B cells in the peripheral blood as compared with Dahl virgin rats. SD rats that received the RUPP procedure had increases in circulating monocytes and increased IFN-ɣ+CD4+ splenic T cells. Together these findings suggest that dysregulated T cell activity is an important factor in both the pregnant Dahl S rats and SD rats after the RUPP procedure.

Naïve, Regulatory, Activated, and Memory Immune Cells Co-exist in PVATs That Are Comparable in Density to Non-PVAT Fats in Health

Perivascular adipose tissue (PVAT), the fat surrounding peripheral blood vessels, is protective and reduces the contraction of blood vessels in health. PVAT is composed of adipocytes, stromal cells, and immune cells. Recent work supports eosinophils as one of the cell types key to the anti-contractile nature of PVAT in health. Hence, we hypothesized that there exists a basally activated immune cell community in healthy PVAT that is distinctly different from non-PVAT fats. PVATs were from around mesenteric resistance vessels (MRPVAT – white fat) and thoracic aorta (APVAT – brown fat). Non-PVATs included retroperitoneal (RP fat – white fat) and subscapular (SS fat – brown fat) while the spleen was a positive control. Tissues were harvested from adult male and female Sprague Dawley rats. Six primary immune cell types were identified in PVATs. T cells (CD4 and CD8), B cells, natural killer (NK) cells, macrophages, mast cells, and neutrophils in the stromal vascular fraction of each fat were identified using nine-color flow cytometry. PVATs contained a higher number of total immune cells vs. their respective non-PVAT fats in females. Females had a higher number of T cells in MRPVAT vs. males. Females also had a greater number of T cells and total immune cells in APVAT vs. males. Further, activation, differentiation, and/or polarization of various immune cell types were similarly determined by flow cytometry. PVATs were similar to their respective non-PVAT fats in density of recently activated B cells (B220+ CD25+). However, MRPVAT in females had a higher number of naïve CD4 T cells vs. MRPVAT in males and APVAT in females. MRPVAT also had denser naïve CD8 T cells vs. APVAT in females. Overall, this research for the first time has identified a community of discrete populations of immune cells (naive/recently activated/regulatory/memory) in healthy PVATs. Contrary to our hypothesis, PVATs are more similar than different in density to their respective non-PVAT fats.

Effects of long term oral acrylamide administration on alpha naphthyl acetate esterase and acid phosphatase activities in the peripheral blood lymphocytes of rats

Acrylamide is an important industrial chemical; it also is formed in starch-rich foodstuffs during baking, frying and roasting. Most acrylamide exposure occurs by ingestion of processed foods. We investigated possible immunotoxic effects of extended administration of low doses of acrylamide in rats. To do this, we measured alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (ACP-ase) activities in peripheral blood lymphocytes. Male and female weanling Wistar rats were administered 2 or 5 mg acrylamide/kg/day in drinking water for 90 days. Peripheral blood was sampled at the end of the administration period. We found ANAE staining in eosinophils and T-lymphocytes, but not in monocytes, platelets, B-lymphocytes and neutrophils. ACP-ase was found in B-lymphocytes. We found a significant reduction of the ratio of ANAE:ACP-ase in lymphocytes of the experimental animals compared to controls. We found no statistically significant differences between the doses or sexes. We found that acrylamide ingested in processed foods might affect the immune system adversely by decreasing the population of mature T- and B-lymphocytes.

Immunophenotyping: Application to Safety Assessment

A continuing education course entitled “What You Always Wanted to Know About Immunotoxicology in Pharmaceutical Development…But Were Afraid to Ask” was offered at the Society of Toxicologic Pathology (STP) 36th annual symposium in Montreal. This article summarizes some key points made during the presentation dedicated to immunophenotyping. It describes how clusters of differentiation (CDs) are well-defined antigens used to characterize cell subsets, and how lymphocyte subsets in humans and different rodent and nonrodent species can be defined by detection of various combinations of CDs. It provides an overview of immunophenotyping study design considerations and applications to safety assessment.

Xenogeneic Mesenchymal Stromal Cells Improve Wound Healing and Modulate the Immune Response in an Extensive Burn Model

Major skin burns are difficult to treat. Patients often require special care and long-term hospitalization. Besides specific complications associated with the wounds themselves, there may be impairment of the immune system and of other organs. Mesenchymal stromal cells (MSCs) are a recent therapeutic alternative to treat burns, mainly aiming to accelerate the healing process. Several MSC properties favor their use as therapeutic approach, as they promote angiogenesis, stimulate regeneration, and enhance the immunoregulatory function. Moreover, since patients with extensive burns require urgent treatment and because the expansion of autologous MSCs is a time-consuming process, in this present study we chose to evaluate the therapeutic potential of xenogeneic MSCs in the treatment of severe burns in rats. MSCs were isolated from mouse bone marrow, expanded in vitro, and intradermally injected in the periphery of burn wounds. MSC-treated rats presented higher survival rates (76.19%) than control animals treated with PBS (60.86%, p < 0.05). In addition, 60 days after the thermal injury, the MSC-treated group showed larger proportion of healed areas within the burn wounds (90.81 ± 5.05%) than the PBS-treated group (76.11 ± 3.46%, p = 0.03). We also observed that CD4(+) and CD8(+) T cells in spleens and in damaged skin, as well as the percentage of neutrophils in the burned area, were modulated by MSC treatment. Plasma cytokine (TGF-β, IL-10, IL-6, and CINC-1) levels were also altered in the MSC-treated rats, when compared to controls. Number of injected GFP(+) MSCs progressively decreased over time, and 60 days after injection, few MSCs were still detected in the skin of treated animals. This study demonstrates the therapeutic effectiveness of intradermal application of MSCs in a rat model of deep burns, providing basis for future regenerative therapies in patients suffering from deep burn injuries.

Aflatoxin B1 modulates the expression of phenotypic markers and cytokines by splenic lymphocytes of male F344 rats

Aflatoxin B1 (AFB1) is immunotoxic to animals and a suspected immunosuppressant in humans. In this study, we investigated the effects of AFB1 on splenic lymphocyte phenotypes and the inflammatory cytokine expression in male F344 rats. Exposure of animals to AFB1 [5-75 µg kg(-1) body weight (BW)] for 1 week showed dose-dependent decreases in the percentage of splenic CD8(+) T cells and CD3(-) CD8a(+) NK cells. A general inhibition of the expression of interleukin (IL)-4 and interferon (IFN)-γ by CD4(+) T cells, IL-4 and IFN-γ by CD8a(+) cells, and tumor necrosis factor (TNF)-α expression by natural killer (NK) cells was also found; however, no concurrent histological changes in spleen tissue were present, suggesting acute immunosuppression without overt toxicity. Five-week exposure with AFB1 significantly increased the percentages of CD3(+) and CD8(+) T cells, especially at low doses (≤ 25 µg kg(-1)). AFB1 treatment significantly decreased the anti-inflammatory cytokine IL-4 expression by CD4(+) T cells and significantly increased the pro-inflammatory cytokine IFN-γ expression by CD4(+) T cells and TNF-α expression by NK cells. These results indicated that repeated AFB1 exposure promotes inflammatory responses by regulating cytokine expression. Our data provides novel insights into the mechanisms by which AFB1 exposure differentially modulates the cell-mediated immune responses and suggests the involvement of an inflammatory response upon repeated exposure.

The dose-dependent immunoregulatory effects of the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester in rats with sub-acute peritonitis

BACKGROUND

Chronic inflammation accompanied by arginine deficiency, immune dysfunction, and excess nitric oxide (NO) production is a clinical condition found in patients with peritonitis. A previous study showed that the nonselective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) may facilitate the metabolism of the immune nutrient arginine without altering NO homeostasis in rats with sub-acute peritonitis. Here, we investigated the effects of L-NAME on the immunocytic subpopulation distribution and response.

MATERIALS AND METHODS

Male Wistar rats with cecal puncture-induced peritonitis were administered parenteral nutrition solutions supplemented with 0 (CPP group), 5 (LNA group), 25 (MNA group) or 50 (HNA group) mg · kg(-1) · day(-1) of L-NAME for 7 days. Parenteral-fed sham-operated rats (TPN group) and orally-fed healthy rats (R group) were included as controls.

RESULTS

The TPN group had significantly increased spleen weights and levels of plasma nitrite/nitrate (NOx), circulating white blood cells (WBC), and splenocytic T cells, as well as significantly decreased levels of cytotoxic T- and B-leukocytes and B-splenocytes compared to the R group. The CPP group had significantly decreased levels of plasma NOx and concanavalin (Con) A-stimulated interferon (IFN)-γ and interleukin (IL)-2 production by leukocytes and significantly increased production of Con A-stimulated tumor necrosis factor (TNF)-α and lipopolysaccharide (LPS)-stimulated IFN-γ in the leukocytes. In addition, the LNA and MNA groups had significantly decreased spontaneous IL-6 and Con A-stimulated TNF-α and IFN-γ production by the leukocytes while the HNA group had significantly increased LPS-stimulated TNF-α and Con A-stimulated IFN-γ and IL-2 production by the splenocytes compared to the CPP group.

CONCLUSIONS

Low-dose L-NAME infusion may suppress proinflammatory and T-helper-1 (Th1) response in leukocytes, and high-dose infusion may activate the proinflammatory response in splenic macrophages and Th1 response in T-splenocytes in rats with sub-acute peritonitis.

Data on Wistar Hannover rats from an immunotoxicity study

The aim of this study was to collect data on immunological parameters from Wistar Hannover rats at 8, 10, 19, and 32 weeks of age. Low leukocyte parameter cell counts, serum globulin concentration, and T, B, and NK lymphocyte counts in peripheral blood at each time point; low T, B, and NK splenocyte counts; and high, or tendencies toward high, thymocyte counts at 10 weeks of age were noted in females when compared with males. KLH-specific antibody production increased gradually with age in both sexes. The immunological data noted for leukocyte parameters, the serum globulin concentration, and immunophenotyping (peripheral blood, spleen, and thymus) relating to chronological changes and sex differences may be useful in assessing drug-related immunotoxicity in this strain.

Curcumin, myrecen and cineol modulate the percentage of lymphocyte subsets altered by 2,3,7, 8-tetracholorodibenzo-p-dioxins (TCDD) in rats

The aim of this study was to investigate the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental pollutant, on the percentage of T-cell subsets and B-lymphocyte and effectiveness of curcumin, β-myrcene (myrcene) and 1,8-cineole (cineol) on this toxicity in rats. Rats (n = 112) were divided randomly into 8 equal groups. One group was kept as control and given corn oil as carrier. TCDD was orally administered at the dose of 2 µg/kg/week. Curcumin, myrcene and cineol were orally administered by gavages at the doses of 100, 200 and 100 mg/kg/day, respectively, dissolved in corn oil with and without TCDD. The blood samples were taken from half of the rats on day 30 and from the rest on day 60 for the determination of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD161(+), CD45RA, CD4(+)CD25(+) and total lymphocyte). The results indicated that although TCDD significantly (p < 0.05) decreased the percentage of CD3(+), CD4(+), CD161(+), CD45RA, CD4(+)CD25(+) and total lymphocyte, it caused a significant increase in the percentage of CD8(+) cells. In contrast, curcumin, myrcene and cineol significantly decreased CD8(+) cells levels but increased CD3(+), CD4(+), CD161(+), CD45RA, CD4(+)CD25(+) and total lymphocyte cells populations. The beneficial effects of curcumin, myrcene and cineol and the toxic effects of TCDD were increased at day 60 compared to day 30. In conclusion, curcumin, myrcene and cineol showed immunomodulatory effects and eliminated TCDD-induced immune suppressive effects in rats.

Adoptive transfer of peripheral immune cells potentiates allodynia in a graded chronic constriction injury model of neuropathic pain

Recent evidence demonstrates that peripheral immune cells contribute to the nociceptive hypersensitivity associated with neuropathic pain by infiltrating the central nervous system (CNS). We have recently developed a rat model of graded chronic constriction injury (CCI) by varying the exposure of the sciatic nerve and control non-nerve tissue to surgical placement of chromic gut. We demonstrate that splenocytes can contribute significantly to CCI-induced allodynia, as adoptive transfer of these cells from high pain donors to low pain recipients potentiates allodynia (P<0.001). The phenomenon was replicated with peripheral blood mononuclear cells (P<0.001). Adoptive transfer of allodynia was not achieved in sham recipients, indicating that peripheral immune cells are only capable of potentiating existing allodynia, rather than establishing allodynia. As adoptively transferred cells were found by flow cytometry to migrate to the spleen (P<0.05) and potentiation of allodynia was prevented in splenectomised low pain recipients, adoptive transfer of high pain splenocytes may induce the migration of host-derived immune cells from the spleen to the CNS as observed by flow cytometry (P<0.05). Importantly, intrathecal transfer of CD45(+) cells prepared from spinal cords of high pain donors into low pain recipients led to potentiated allodynia (P<0.001), confirming that infiltrating immune cells are not passive bystanders, but actively contribute to nociceptive hypersensitivity in the lumbar spinal cord.

Developmental vitamin D3 deficiency induces alterations in immune organ morphology and function in adult offspring

Vitamin D3 deficiency and insufficiency are common in women of child-bearing age. This may be cause for concern because vitamin D3 is a well known regulator of immune function and epidemiological evidence has suggested that immune disorders, including autoimmune diseases, could have developmental origins. However, it is not known whether a developmental deficiency in vitamin D3 could lead to persistent changes in the immune system in adult offspring. Given the prominence of receptors for vitamin D3 within immune cells we hypothesised that the developmental absence of vitamin D3 may alter thymic development and thus produce associated functional changes in T cells. We have developed a model of developmental vitamin D3 (DVD) deficiency in Sprague-Dawley rats, in which the vitamin D3 deficiency is transient and restricted to gestation. First we demonstrate that DVD deficiency induced an increase in central but not peripheral immune organ size. Second when stimulated, lymphocytes from DVD-deficient rats exhibit a pro-inflammatory phenotype. This is the first study to show that a transient vitamin D3 deficiency restricted to gestation can persistently alter aspects of immune phenotype and function in the adult offspring. Given an increased incidence of vitamin D3 deficiency in women of child-bearing age these findings may be highly relevant for autoimmune disorders with a developmental basis.

A semi-physiological-based pharmacokinetic/pharmacodynamic model to describe the effects of topotecan on b-lymphocyte lineage cells

PURPOSE

To develop a semi-physiological-based model describing simultaneously the time course of immature and mature B-lymphocytes after topotecan (TPT) administration to tumor-bearing rats.

METHODS

Twenty-four tumor-bearing BDIX male rats received a single 6 mg/kg intra-peritoneal dose of TPT or saline. Mature and immature B-cell levels were measured every two days during three weeks and showed a very different temporal pattern. Both B-cell populations declined rapidly, reaching the nadir at 3-4 days after TPT administration; however, mature cells returned to baseline at day 8, while immature B-cells stayed at nadir until day 9 instead. Data were modeled using the population approach with NONMEM VI.

RESULTS

The model developed maintains the proliferation, maturation and degradation elements of previous published models for myelosuppresion. In order to describe the rapid recovery of mature cells, it includes a peripheral compartment providing a constant supply of mature cells to the bloodstream.

CONCLUSIONS

The major contribution of the model is its new structure and the dynamical consequences, demonstrating an independent behavior between mature and immature B-cells during recovery. The final model could represent a good basis for the optimization of cytotoxic drugs oriented to attain a maximum antitumor efficacy while minimizing hematological toxicity.

Modulation of NKT cells and Th1/Th2 imbalance after alpha-GalCer treatment in progressive load-trained rats

Purpose: The purpose of this study was to determine whether α-galactosylceramide (α-GalCer), a synthetic glycolipid agonist of natural killer T (NKT) cells, can ameliorate exercise-induced immune imbalance. Methods: Eight-week-old female Sprague-Dawley rats were trained with a progressively increasing load for 9 weeks. At 36 h and at 7 d after training, groups of rats were euthanized. The whole blood was used to detect hemoglobin(Hb), plasma was analyzed for hormones testosterone(T) and corticosterone(C), and spleen was harvested for detecting NKT cells and interferon-γ (IFN-γ) and interleukin (IL)-4 producing cells. Results: Two-way analysis of variance (ANOVA) showed significant differences between training and time in Series 1. The results showed, at 36h after training, that the decrease in Hb, T and C concentration reflected overtraining or excessive exercise. At 7 d after training, NKT cell populations decreased, and a T helper 1/T helper 2 (Th1/Th2) lymphocyte imbalance occurred. In Series 2, α-galactosylceramide (α-GalCer), an NKT cell activator was found to enhance NKT cell numbers by 69% and shift the Th1/Th2 lymphocyte imbalance by observably decreasing the frequency of IL-4 secreting cells. Conclusion: These data showed that, in addition to Th1/Th2 self-regulation, α-GalCer played an important modulatory role in the exercise-induced Th1/Th2 lymphocyte imbalance, which may be correlative with NKT immunoregulatory cells.

SIMULTANEOUS MEASUREMENT OF NUCLEATED CELL COUNTS AND CELLULAR DIFFERENTIALS IN RAT BONE MARROW EXAMINATION USING FLOW CYTOMETER

The purpose of this study was to establish the simultaneous measurement of nucleated cell counts and cellular differentials in rat bone marrow examination. The bone marrow cells were stained with an anthraquinone fluorescent DNA stain (DRAQ5) and fluorescence-labeled antibodies, and were analyzed quantitatively using a flow cytometer in the presence of internal standard beads. DRAQ5 distinguished populations of nucleated cells. The absolute counts of nucleated cells were determined using an internal standard, and were equivalent to that measured by the electrical resistance method. The population of nucleated cells was classified into myeloids and erythroids by labeling with CD11b/c and CD71 antibodies, respectively. In a separate examination, T- and B-lymphocytes were also classified by labeling with CD3 and CD45RA antibodies, respectively. The classification of each cell lineage was identical with that of the alternative flow-cytometric method in which cells were differentiated according to cellular size and the fluorescence of a peroxidase indicator, 2',7'-dichlorofluorescin. The ratios of cell lineage, together with myeloid/erythroid ratio (ME), were the same as those obtained by a manual microscopic method. The present flow cytometric method enables the simultaneous measurement of the total nucleated cell counts and cellular differentials of rat bone marrow cells, allowing for rapid and highly quantitative bone marrow examination in rats.

Possible involvement of 4-hydroxynonenal in splenocyte regulated liver regeneration

Liver regeneration is a complex, systemic process regulated by humoral and cellular mechanisms. Inflammatory response to the extensive tissue damage, as in partial hepatectomy, plays important role during regeneration. Hence, it is assumed that the spleen might play a role in systemic inflammatory response involved in liver regeneration. On the other hand, liver damage and consequential regeneration are often associated with oxidative stress and lipid peroxidation. One of the end products of lipid peroxidation, 4-hydroxynonenal (HNE), is nowadays considered not only as a "second toxic messenger of free radicals" but also as a growth-regulating factor. We therefore studied in vitro interactions of the HNE-treated murine liver cells and autologous spleen cells. The spleen cells supported recovery of liver cells from the HNE cytotoxicity although spleen cells themselves exerted cytotoxic effects against the proliferating liver cells that were not treated with HNE. Our results imply that the cytokines secreted by activated immunocompetent cells may be responsible for the observed recovery of the HNE-damage liver cells, suggesting that HNE might be an important factor regulating cellular and cytokine mediated mechanisms of liver regeneration control.

A small-volume technique for simultaneous immunophenotyping and apoptosis detection in rat whole blood by four-color flow cytometry

BACKGROUND

Cell permeabilization for the detection of intracellular molecules by flow cytometry is usually incompatible with whole blood. This article describes a new technique for the simultaneous detection of surface antigens and DNA content in rat whole blood.

METHODS

In 20 microl of rat whole blood, DNA staining is obtained by permeabilization of cells using a standard red blood cell lysing reagent (Erythrolyse). Immunophenotyping and apoptosis detection by flow cytometry are achieved by using a combination of three surface markers (CD3, CD4, and CD8alpha) and a DNA binding dye (TO-PRO-3).

RESULTS

After a 24-h incubation of whole blood with 1 microM dexamethasone, apoptotic lymphocytes were clearly distinguishable from normal lymphocytes by their reduced size and DNA content. The dexamethasone-induced percentage of apoptotic cells was 58.9 +/- 4.6 for CD4+ and 77.4 +/- 2.9 for CD8+ T cells, compared with 12.6 +/- 2.7 for CD4+ and 17.2 +/- 3.5 for CD8+ T cells in the absence of dexamethasone (data from 10 animals with duplicate samples).

CONCLUSIONS

We have developed a new technique to permeabilize nucleated cells in microsamples of rat whole blood. The methodology allows simultaneous immunophenotyping and apoptosis detection in rat whole blood.

Coexpression of CD4 and CD8alpha on rat T-cells in whole blood: a sensitive marker for monitoring T-cell immunosuppressive drugs

The aim of this study was to develop a new quantitative method for measuring in vitro the effects of T-cell immunosuppressive drugs by flow cytometry. Rat whole blood samples were stimulated with the T-cell mitogen succinylated concanavalin A in the presence or absence of different drugs. After 3 days, the expression of CD25 and CD8alpha in mitogen-stimulated CD4(+) cells increased 10- to 20-fold as measured by flow cytometry. Drug efficacy and potency was calculated based on dose-response curves of the drug-mediated decrease in CD4(+)/CD8alpha(+)/CD25(+) cells. The expression of CD8alpha in mitogen-stimulated CD4(+) cells was blocked completely by calcineurin inhibitors (cyclosporine A and FK-506), and partially by rapamycin and SDZ-RAD. The IC(50) (50% inhibitory concentration) values obtained were (mean+/-S.E.): 99.5+/-16.6 nM for cyclosporine A, 10.4+/-1.3 nM for FK-506, 1.8+/-0.7 nM for rapamycin, and 6.4+/-1.1 nM for SDZ-RAD. Our results show, for the first time, that CD8alpha, used as an activation antigen, is a sensitive marker for monitoring T-cell immunosuppression.

Human and rat mononuclear cell proliferation show different sensitivity, in vitro, to single constituents of dental composite resins

The aim of this study was to evaluate the effect of 11 constituents of dental composite resins on ConA-induced proliferation of rat mononuclear cells. We also wanted to compare the sensitivity of rat and human mononuclear cells, to find out if results from a rat cell assay could be extrapolated to human conditions. The variable used for this purpose was the dose at 50% inhibition of proliferation (ID(50)). Mononuclear cells derived from rat spleens and human venous blood were used. The effects of the substances on rat and human cell proliferation were evaluated with and without stimulation by Concanavalin A. The ID(50) rank order of the tested substance categories was similar for both species, i.e., the monomers inhibited at the lowest concentration, the stabilizer at intermediate, and the initiators at the highest concentrations. In spite of a similar inhibition rank order, there were significant differences in sensitivity to the substances between the species. In conclusion, the results from this study together with the fact that the substances are handled by and used in humans, would favor the use of human cells when studying the effect of constituents of dental composite resins in vitro.