Appearance Of CD4 Research Articles

Pulmonary Inflammation and Emphysema

Chronic obstructive pulmonary disease (COPD) is believed to be an inflammatory cytokine-driven disease, but a causal basis that can be associated with a specific cytokine has not been directly demonstrated. We have previously reported that proinflammatory cytokine IL-18 expression is important in the pathogenesis of pulmonary inflammation and lung injury in mice. Our results demonstrate that IL-18 overproduction in the lungs can induce lung diseases, such as pulmonary inflammation, lung fibrosis, and COPD. We analyzed the role of IL-18 in the pathogenesis of COPD. Using the human surfactant protein C promoter to drive expression of mature mouse IL-18 cDNA, we developed two different lines of transgenic (Tg) mice that overproduced mouse mature IL-18 in the lungs either constitutively or in response to doxycycline. Constitutive overproduction of IL-18 in the lungs resulted in the increased production of IFN-gamma, IL-5, and IL-13, and chronic pulmonary lung inflammation with the appearance of CD8+ T cells, macrophages, neutrophils, and eosinophils. Increased lung volume, severe emphysematous change, dilatation of the right ventricle, and mild pulmonary hypertension were observed in (more than 15-wk-old) Tg mice. Interestingly, disruption of the IL-13 gene, but not the IFN-gamma gene, prevented emphysema and pulmonary inflammation in Tg mice. Moreover, when IL-18 production was induced in lung tissues for 4 weeks through the use of a doxycycline-dependent surfactant protein C promoter, interstitial inflammation was induced. Our results indicate that IL-18 and IL-13 may have an important role in the pathogenesis of COPD.

Lymphocyte–hepatic stellate cell proximity suggests a direct interaction

Recent functional research studies suggest an anti-fibrotic role for natural killer (NK) cells coupled with a profibrotic role for CD8 cells. However, the morphological cellular interplay between the different cell types is less clear. To investigate lymphocyte/hepatic stellate cell (HSC) interactions, hepatic fibrosis was induced by administering carbon tetrachloride (CCl4) intraperitoneally (i.p.) for 4 weeks in C57Bl/6 mice. Animals were killed at 0, 1, 2, 3 and 4 weeks. Liver sections were stained for Sirius red. Confocal microscopy was used to evaluate alpha smooth-muscle actin (alphaSMA) and lymphocyte subsets in liver sections. At weeks 0 and 4, liver protein extracts were assessed for alphaSMA by Western blotting and isolated liver lymphocytes as well as HSC were analysed by fluorescence activated cell sorter (FACS). Similar to the results obtained from classical Sirius red staining and alphaSMA blotting, analysis of liver sections by confocal microscopy revealed a marked and continuous accumulation of alphaSMA staining along sequential experimental check-points after administering CCl4. Although the number of all liver lymphocyte subsets increased following fibrosis induction, FACS analysis revealed an increase in the distribution of liver CD8 subsets and a decrease of CD4 T cells. Confocal microscopy showed a significant early appearance of CD8 and NK cells, and to a lesser extent CD4 T cells, appearing only from week 2. Lymphocytes were seen in proximity only to HSC, mainly in the periportal area and along fibrotic septa, suggesting a direct interaction. Notably, lymphocyte subsets were undetectable in naive liver sections. Freshly isolated HCS show high expression of major histocompatibility complex (MHC) class II and CD11c. In the animal model of hepatic fibrosis, lymphocytes infiltrate into the liver parenchyma and it is thought that they attach directly to activated HSC. Because HSCs express CD11c/class II molecules, interactions involving them might reflect that HSCs have an antigen-presenting capacity.

Transcriptional regulation of Th2 differentiation

Naive CD4 T cells have a series of fates open to them; differentiation to Th2 cells depends on the concerted action of three transcription factors, GATA-3, STAT5 and Gfi-1, and displays striking positive reinforcement. The earliest events in Th2 differentiation are T cell receptor driven induction of GATA-3 and of IL-2, the latter activating STAT5. GATA-3 and STAT-5, acting together, lead to early transcription of IL-4. Endogenous IL-4, acting through IL-4Rα and STAT6 strikingly upregulate GATA-3 and IL-4, leading to commitment of the cell to high rate IL-4 production and to the Th2 phenotype. GATA-3 and STAT5 target distinct sites within the Il4 gene, resulting in accessibility and thus the two transcription factors work in concert to activate the gene. Gfi-1 enhances the cytokine driven out-growth of Th2 cells and selects cells expressing the highest amounts of GATA-3. Thus, the interaction of the three transcription factors leads both to Th2 fate determination and selective outgrowth of differentiated Th2 cells and are thus responsible for a robust differentiation process resulting in the appearance of CD4 T cells capable of producing IL-4 and its related cytokines.

Survival adjustment of mature dendritic cells by IL-15

The survival of CD8+/CD44(hi) memory phenotype T cells depends on an IL-15 activity on nonlymphoid cells. Here, we report that IL-15 and its receptor were induced on dendritic cells (DCs) by a combination of IFN-gamma and NF-kappaB relA inducers. IL-15 conferred in an autocrine loop resistance to apoptosis that accompanied the maturation process in DCs in vitro. As an apparent result in vivo, mice deficient in IL-15 or its receptor harbor few DCs. Injecting DCs into IL-15-/- mice was associated with the appearance of CD8+/CD44(hi) T cells that depended on IL-15 expression but also correlated with the longevity of the DCs. These findings support the hypothesis that DCs mediate the effect of IL-15 on CD8+/CD44(hi) memory phenotype T cells.

Impaired immunity to intestinal bacterial infection in stromelysin-1 (matrix metalloproteinase-3)-deficient mice.

Infection of mice with the intestinal bacterial pathogen Citrobacter rodentium results in colonic mucosal hyperplasia and a local Th1 inflammatory response similar to that seen in mouse models of inflammatory bowel disease. Matrix metalloproteinases (MMPs) have been shown to mediate matrix remodeling and cell migration during tissue injury and repair in the intestine. We have previously shown enhanced pathology in infected TNFRp55-/-, IL-12p40-/-, and IFN-gamma-/- mice, and here we show that this is associated with an increase in stromelysin-1 (MMP3) transcripts in colonic tissues. We have therefore investigated the role of MMP3 in colonic mucosal hyperplasia and the local Th1 responses using MMP3-/- mice. In MMP3-/- mice, similar mucosal thickening was observed after infection as in wild-type (WT) mice. Colonic tissues from MMP3-/- mice showed a compensatory increase in the expression of other MMP transcripts, such as MMP7 and MMP12. However, MMP3-/- mice showed delayed clearance of bacteria and delayed appearance of CD4+ T lymphocytes into intestinal lamina propria. CSFE-labeled mesenteric lymph node CD4+ T lymphocytes from infected WT mice migrated in fewer numbers into the mesenteric lymph nodes and colon of MMP3-/- mice than into those of WT mice. These studies show that mucosal remodeling can occur in the absence of MMP3, but that MMP3 plays a role in the migration of CD4+ T lymphocytes to the intestinal mucosa.

Surface antigen expression in spleen cells of C57B1/6 mice during ageing: influence of sex and parity.

So far all studies on the murine ageing process have been conducted on virgin mice. Immune ageing may be influenced by sex hormone differences related to sex or pregnancies. The aim of this study was to investigate whether pregnancies and gender influence the cell changes observed during ageing in a peripheral lymphoid compartment of C57B1/6 mice. Using flow cytometry, changes in (Thy1.2+) T cell, (B220+) B cell and (CD 11b/Mac-1) macrophage spleen populations were monitored in 2, 8 (3 months after last pregnancy) 15 and 23-month-old mice including males, virgin and multiparous females. The development of naive (CD44(low)), memory (CD44(high)), activated/memory (MEL-14, CD62L) cells were investigated in CD4+ and CD8+ T cell subsets. Both short term (at 8 months) and long term (at 15 and 23 months) effects of multiparity were obvious in the lymphocyte/macrophage population changes associated with the ageing process. Short-term effects included delayed appearance of CD4+CD44(high) memory lymphocytes and increased numbers of both CD4+MEL-14(1ow) activated/memory cells and Mac-1+ macrophages when compared with virgin control mice. Later effects of multiparity were increased CD8alpha(dull) populations and increased T/B cell ratios and the ratio of memory to naive CD4+ cells (CD44+(high)/CD44+(low). A sex effect was noticed: males exhibited lower Mac-1+ levels and memory/naive ratio in CD4+ subset than virgin females throughout life. These results suggest that gender and/or pregnancies affect the age-related distribution of lymphoid and macrophage cell populations in the spleen of C57B1/6 mice.

Both mucosal and systemic routes of immunization with the live, attenuated NYVAC/simian immunodeficiency virus SIV(gpe) recombinant vaccine result in gag-specific CD8(+) T-cell responses in mucosal tissues of macaques.

As most human immunodeficiency virus (HIV) infection occurs via mucosal surfaces, an important goal of vaccination may be the induction of virus-specific immune responses at mucosal sites to contain viral infection early on. Here we designed a study in macaques carrying the major histocompatibility complex class I Mamu-A(*)01 molecule to assess the capacity of the highly attenuated poxvirus NYVAC/simian immunodeficiency virus (SIV) SIV(gpe) vaccine candidate administered by the intranasal, intramuscular, or intrarectal route to induce mucosal immunity. All macaques, including one naive macaque, were exposed to SIV(mac251) by the intrarectal route and sacrificed 48 h after infection. The kinetics of immune response at various time points following immunization with NYVAC/SIV(gpe) and the anamnestic response to SIV(mac251) at 48 h after challenge were assessed in blood, in serial rectal and vaginal biopsy samples, and in tissues at euthanasia with an SIV(mac) Gag-specific tetramer. In addition, at euthanasia, antigen-specific cells producing gamma interferon or tumor necrosis factor alpha from the jejunum lamina propria were quantified in all macaques. Surprisingly, antigen-specific CD8(+) T cells were found in the mucosal tissues of all immunized macaques regardless of whether the vaccine was administered by a mucosal route (intranasal or intrarectal) or systemically. In addition, following mucosal SIV(mac251) challenge, antigen-specific responses were mainly confined to mucosal tissues, again regardless of the route of immunization. We conclude that immunization with a live vector vaccine results in the appearance of CD8(+) T-cell responses at mucosal sites even when the vaccine is delivered by nonmucosal routes.

CD103 expression is required for destruction of pancreatic islet allografts by CD8(+) T cells.

The mechanisms by which CD8 effector populations interact with epithelial layers is a poorly defined aspect of adaptive immunity. Recognition that CD8 effectors have the capacity to express CD103, an integrin directed to the epithelial cell-specific ligand E-cadherin, potentially provides insight into such interactions. To assess the role of CD103 in promoting CD8-mediated destruction of epithelial layers, we herein examined the capacity of mice with targeted disruption of CD103 to reject pancreatic islet allografts. Wild-type hosts uniformly rejected islet allografts, concomitant with the appearance of CD8+CD103+ effectors at the graft site. In contrast, the majority of islet allografts transplanted into CD103−/− hosts survived indefinitely. Transfer of wild-type CD8 cells into CD103−/− hosts elicited prompt rejection of long-surviving islet allografts, whereas CD103−/− CD8 cells were completely ineffectual, demonstrating that the defect resides at the level of the CD8 cell. CD8 cells in CD103−/− hosts exhibited normal effector responses to donor alloantigens in vitro and trafficked normally to the graft site, but strikingly failed to infiltrate the islet allograft itself. These data establish a causal relationship between CD8+CD103+ effectors and destruction of graft epithelial elements and suggest that CD103 critically functions to promote intragraft migration of CD8 effectors into epithelial compartments.

Significant role of Fas ligand-binding but defective Fas receptor (CD95) in lymph node hyperplasia composed of abnormal double-negative T cells.

The functional differences between two mutations of the Fas (CD95) locus, Faslpr (lpr) and Faslprcg (lprcg), were investigated using bone marrow (BM) transplantation on the C3H mouse background. Both lpr/lpr and lprcg/lprcg BM transferred caused lymph node (LN) hyperplasia in lpr/+ and lprcg/+ recipients, although it was clearly smaller than that in lpr/lpr and lprcg/lprcg recipients of lpr/lpr and lprcg/lprcg BM. In addition, both BM induced significantly larger LN hyperplasia in lprcg/+ than lpr/+ recipients. Appearance of CD4- CD8-[double negative (DN)] T cells in the periphery is the most consistent phenotype of Fas mutations. Importantly, the proportion of DN T cells was higher in larger LN hyperplasia in the order of lpr/+, lprcg/+ and lpr/lpr or lprcg/lprcg recipients. On the other hand, both lpr/lpr and lprcg/lprcg BM transferred into wild-type (+/+) mice caused marked LN atrophy. The former, but not the latter, induced wasting syndrome. Faslg1d (gld)-homozygous lpr/lpr BM transferred into +/+ mice elicited LN hyperplasia of the same extent as that in lpr/lpr mice transferred with lpr/lpr BM, but not wasting syndrome. Taken together with the fact that DN T cells massively express Fas ligand (FasL), this study implied that FasL overexpressed on DN cells may be involved in the accumulation of DN T cells in LN, LN atrophy and wasting syndrome, and that lprcg Fas, which can bind to Fas ligand but not transduce apoptosis signal into cells, may modulate these pathological conditions by interfering with the binding of FasL to Fas.

Murine AIDS Induces Viremia and Functional and Phenotypic Alterations in Blood Cells

Background: Murine acquired immunodeficiency syndrome (MAIDS) is characterized by generalized lymphoproliferation and progressive immunodeficiency. It is induced by a mixture of two replication-competent murine leukemia viruses (MuLV) and a disease-causing, replication-incompetent defective MuLV. Infection leads to specific phenotypic and functional alterations of lymphocytes in lymphoid organs. Methods: We analyzed phenotypic, virological and functional parameters in the blood of mice infected with MAIDS virus. Results: Disease progression correlated with increasing viremia, a loss of mitogen responsiveness of T lymphocytes, and the appearance of CD4+ Thy1– T lymphocytes. At >9 weeks after infection, the distribution of leukocyte cell populations became very heterogeneous, and late-stage leukemic events were observed in 5 of 23 mice. Conclusions: Virus titers, mitogen responsiveness and the presence of CD4+ Thy1– T lymphocytes can efficiently be monitored in the blood and serve as diagnostic parameters to monitor disease progression. Acute leukemic events occurring at the terminal stage could be responsible for the death of at least some of the mice with MAIDS.

Combined Deletion of CD8 Locus cis-Regulatory Elements Affects Initiation but Not Maintenance of CD8 Expression

Developmental stage-, subset-, and lineage-specific CD8 enhancers have been identified recently by transgenic reporter analyses. Enhancer E8 II (CIV-4,5) is active in both immature double-positive thymocytes (DP) and mature CD8 single-positive (SP) thymocytes and T cells, whereas E8 I (CIII-1,2) directs expression only in mature cells. In mice lacking either E8 I (CIII-1,2) or E8 II (CIV-4,5), there was no effect on CD8 expression in DP thymocytes. However, deletion of both enhancers resulted in variegated expression of CD8, with appearance of CD4 +CD8 − SP thymocytes expressing surface markers characteristic of DP thymocytes. Consequently, fewer mature CD8 + T cells developed from the reduced pool of DP cells. These results suggest that the initiation of CD8 expression is mediated by cis-regulatory elements that are distinct from any that may be involved in maintenance of expression.

Early development of immune system in pigs

Prenatal and early postnatal immune system development has been studied in minipigs. First leukocytes were observed in the yolk sac and fetal liver (FL) on the 17th day of gestation, the majority of them being SWC3 +. The colonization of the thymus (TH) with leukocytes was observed 21 days later. Two waves of fetal TH colonization with pro-T cells were deduced from the frequency of thymocyte subsets. Thymic B cells and immunoglobulin-secreting cells (Ig-SC) were studied by flow cytometry and ELISPOT, respectively. When the total numbers of fetal Ig-SC were compared, the TH was identified as the main source of natural antibodies and the only site of IgA and IgG synthesis. In germ-free animals, the TH also represented the major site of IgG and IgA production and the number of Ig-SC was not influenced by colonization with microflora. FL and bone marrow were identified as primary B lymphopoietic sites. The phenotype of B precursors was characterized and pre-B II cells were shown to be the dominant mononuclear fraction between DG50 and DG105. In the periphery, relative proportions of lymphocyte subsets were determined. Studies in gnotobiotic piglets have revealed that the appearance of CD4 +CD8 + T cells and CD2 − B cells is absolutely dependent on the contact of immune system with live viruses and bacteria, respectively.

Long-term influence of lipid nutrition on the induction of CD8 + responses to viral or bacterial antigens

Porcine CD8 + lymphocytes are critical for the development of cellular immune responses to bacterial (i.e. CD8αα +) and viral (i.e. CD8αβ + lymphocytes) pathogens. Vaccination and challenge modulate the kinetics of appearance of CD8 + cells in peripheral blood. In addition to antigen-mediated modulation, nutritional modulation can also influence cell-mediated immunity. We had previously observed that diets supplemented with a mixture of conjugated linoleic acid (CLA) isomers expanded porcine CD8 + peripheral blood mononuclear cells (PBMC). The present study aimed to investigate the influence of prior consumption of a nutraceutical, (i.e. dietary CLA) on phenotypes and effector functions of porcine PBMC following immunization with a bacterin or a modified-live viral vaccine. It was demonstrated that the effects of dietary CLA on immune cell phenotype (i.e. numbers of CD8αβ + cells) persisted after the compound was withdrawn from the diet (i.e. 67 days), whereas effector functions (i.e. antigen-stimulated proliferation and cytotoxycity) disappeared earlier (i.e. 25 days). Specifically, numbers of CD8αβ + PBMC in pigs that had been fed diets suplemented with CLA were greater than in pigs fed control (i.e. isoenergetic and unsupplemented) diets, regardless of the vaccination treatment. Furthermore, prior dietary CLA supplementation interacted with viral immunization (i.e. modified-live pseudorabies virus (PRV) vaccine) by enhancing both pseudorabies-specific proliferative responses of CD8αβ + PBMC and granzyme activities of PBMC.

Competitive inhibition in vivo and skewing of the T cell repertoire of antigen-specific CTL priming by an anti-peptide-MHC monoclonal antibody.

We have recently described a mAb, KP15, directed against the MHC-I/peptide molecular complex consisting of H-2D(d) and a decamer peptide corresponding to residues 311-320 of the HIV IIIB envelope glycoprotein gp160. When administered at the time of primary immunization with a vaccinia virus vector encoding gp160, the mAb blocks the subsequent appearance of CD8(+) CTL with specificity for the immunodominant Ag, P18-I10, presented by H-2D(d). This inhibition is specific for this particular peptide Ag; another H-2D(d)-restricted gp160 encoded epitope from a different HIV strain is not affected, and an H-2L(d)-restricted epitope encoded by the viral vector is also not affected. Using functional assays and specific immunofluorescent staining with multivalent, labeled H-2D(d)/P18-I10 complexes (tetramers), we have enumerated the effects of blocking of priming on the subsequent appearance, avidity, and TCR Vbeta usage of Ag-specific CTL. Ab blocking skews the proportion of high avidity cells emerging from immunization. Surprisingly, Vbeta7-bearing Ag-specific TCR are predominantly inhibited, while TCR of several other families studied are not affected. The ability of a specific MHC/peptide mAb to inhibit and divert the CD8(+) T cell response holds implications for vaccine design and approaches to modulate the immune response in autoimmunity.

Recovery of immune reactivity after T-cell–depleted bone marrow transplantation depends on thymic activity

To evaluate the importance of the thymus for the reconstitution of immunity in recipients of a T-cell-depleted bone marrow, we measured the appearance of CD4(+)CD45RA(+)RO(-) naive T cells (thymic rebound), restoration of the diversity of the T-cell-receptor (TCR) repertoire and the response to vaccinations with tetanus toxoid (TT). Repopulation by CD4(+)CD45RA(+)RO(-) thymic emigrants varied among patients, starting at approximately 6 months after transplantation. Young patients reconstituted swiftly, whereas in older patients, the recovery of normal numbers of naive CD4(+) T cells could take several years. Restoration of TCR diversity was correlated with the number of naive CD4(+)CD45RA(+)RO(-) T cells. Moreover, the extent of the thymic rebound correlated with the patient's capacity to respond to vaccinations. Patients without a significant thymic rebound at the moment of vaccination (CD4(+)CD45RA(+)RO(-) T cells less than 30 microL) did not respond, or responded only marginally even after 3 boosts with TT. We conclude that during the first year after transplantation, the absence of an immune response is due mainly to the loss of an adequate T-cell repertoire. Restoration of the repertoire can come only from a thymic rebound that can be monitored by measuring the increase of CD4(+)CD45RA(+)RO(-) naive T cells. This will allow postponing revaccinations to a moment when the patient will be able to respond more effectively. This may be particularly useful in the elderly patient who, owing to low thymic activity, might not yet be able to respond 1 year after transplant when revaccinations are usually scheduled.

Recovery of immune reactivity after T-cell–depleted bone marrow transplantation depends on thymic activity

AbstractTo evaluate the importance of the thymus for the reconstitution of immunity in recipients of a T-cell–depleted bone marrow, we measured the appearance of CD4+CD45RA+RO−naive T cells (thymic rebound), restoration of the diversity of the T-cell–receptor (TCR) repertoire and the response to vaccinations with tetanus toxoid (TT). Repopulation by CD4+CD45RA+RO− thymic emigrants varied among patients, starting at approximately 6 months after transplantation. Young patients reconstituted swiftly, whereas in older patients, the recovery of normal numbers of naive CD4+ T cells could take several years. Restoration of TCR diversity was correlated with the number of naive CD4+CD45RA+RO− T cells. Moreover, the extent of the thymic rebound correlated with the patient's capacity to respond to vaccinations. Patients without a significant thymic rebound at the moment of vaccination (CD4+CD45RA+RO− T cells less than 30 μL) did not respond, or responded only marginally even after 3 boosts with TT. We conclude that during the first year after transplantation, the absence of an immune response is due mainly to the loss of an adequate T-cell repertoire. Restoration of the repertoire can come only from a thymic rebound that can be monitored by measuring the increase of CD4+CD45RA+RO−naive T cells. This will allow postponing revaccinations to a moment when the patient will be able to respond more effectively. This may be particularly useful in the elderly patient who, owing to low thymic activity, might not yet be able to respond 1 year after transplant when revaccinations are usually scheduled.

Apoptosis and Regeneration of Hepatocytes during Recovery from Transient Hepadnavirus Infections

It is well known that hepatitis B virus infections can be transient or chronic, but the basis for this dichotomy is not known. To gain insight into the mechanism responsible for the clearance of hepadnavirus infections, we have performed a molecular and histologic analysis of liver tissues obtained from transiently infected woodchucks during the critical phase of the recovery period. We found as expected that clearance from transient infections occurred subsequent to the appearance of CD4(+) and CD8(+) T cells and the production of interferon gamma and tumor necrosis factor alpha in the infected liver. These events were accompanied by a significant increase in apoptosis and regeneration of hepatocytes. Surprisingly, however, accumulation of virus-free hepatocytes was delayed for several weeks following this initial influx of lymphocytes. In addition, we observed that chronically infected animals can exhibit levels of T-cell accumulation, cytokine expression, and apoptosis that are comparable with those observed during the initial phase of transient infections. Our results are most consistent with a model for recovery predicting replacement of infected hepatocytes with regenerated cells, which by unknown mechanisms remain protected from reinfection in animals that can be cured.

Early emergence of CD8(+) T cells primed for production of type 1 cytokines in the lungs of Mycobacterium tuberculosis-infected mice.

Several lines of evidence suggest that CD8 T cells are important in protection against tuberculosis. To understand the function of this cell population in the immune response against Mycobacterium tuberculosis, T cells from lungs of M. tuberculosis-infected mice were examined by flow cytometry. The kinetics of the appearance of CD8 T cells in lungs of infected mice closely paralleled that of CD4 T cells. Both CD4(+) and CD8(+) T cells displaying an activated phenotype were found in the lungs as early as 1 week postinfection. By 2 weeks, total cell numbers in the lungs had tripled and percentages of T cells were increased two- to threefold; the percentages of CD4(+) T cells were ca. twofold higher than those of CD8(+) T cells. Short-term stimulation with M. tuberculosis-infected antigen-presenting cells induced cytokine production by primed CD4(+) and CD8(+) T cells. Intracellular cytokine staining revealed that 30% +/- 5% of CD4(+) and 23% +/- 4% of CD8(+) T cells were primed for production of gamma interferon (IFN-gamma). However, a difference in in vivo IFN-gamma production by T cells was observed with approximately 12% of CD4(+) T cells and approximately 5% of CD8(+) T cells secreting cytokine in the lungs at any given time during infection. The data presented indicate that although early in infection the majority of IFN-gamma is produced by CD4(+) T cells, cytokine-producing CD8(+) T cells are readily available when triggered by the appropriate stimuli.

Cervical lymph nodes play the role of regional lymph nodes in brain tumour immunity in rats.

Recent physiological and anatomical studies have demonstrated that a major fraction of brain interstitial and cerebrospinal fluid drains into cervical lymph nodes (CLN) in a number of experimental animals. To investigate the role of CLN in brain tumour immunity, temporal profiles of MHC class II molecule expression and T lymphocyte subsets in brain tumours, CLN and other lymphoid tissues were analysed by immunocytochemistry. A total of 64 Wistar rats weighing 250 g were used. Two weeks after the transplantation of C6 glioma cells (10(6) cells/1 microl) into a rat brain, expression of MHC class II molecules was induced in the brain and all systemic lymphoid tissues examined. However, the subsequent appearance of CD4 or CD8 positive cells was strictly confined to CLN, and coincided with the infiltration of such cells into the brain tumour 2 weeks after transplantation. In the group of animals in which cervical lymphadenectomy was followed by intracerebral transplantation of C6 glioma cells, infiltration of CD4 or CD8 positive cells into the brain tumour was delayed until 3 weeks after the transplantation, and the production of such cells was by the spleen. These results suggest that CLN act as regional lymph nodes in brain tumour immunity.

Expression of granzyme B during primary cytomegalovirus infection after renal transplantation.

CD8+ T cells employ granzyme B (GrB) to induce apoptosis in target cells. Increased expression of GrB has been put forward as a diagnostic marker in transplant rejection and viral infection. Three-color flow cytometric analysis revealed that peripheral blood CD8+ T lymphocytosis during primary cytomegalovirus infection after renal transplantation resulted from expansion of a CD8+GrB+CD62L+ T cell subset that was almost absent during stable transplant function or acute rejection. This expansion coincided with a temporary increase in systemic soluble GrB (sGrB) levels. No such increase was observed during stable transplant function or acute rejection. Thus, the primary immune response to cytomegalovirus infection is accompanied by appearance of CD8+GrB+CD62L+ T cells and increased sGrB levels in the peripheral blood compartment. Determination of the latter may provide a novel approach for monitoring viral infections.