Expression In Lymphoid Tissues Research Articles

Alterations in CD4+, CD8+, Vγ3, Vγδ, and/or Vα βT-Lymphocyte Expression in Lymphoid Tissues of Progeny After In Utero Exposure to Benzo(α)pyrene

That benzo〈 α)pyrene (Bα P) decreases both humoral and cell-mediated immunity, and leads to increases in progeny tumor development after in utero insult, suggests that T- and B-lymphocytes are made defective in exposed offspring. In the study here, C3H mice were injected once with Bα P (150 μ g/g BW) at day 12 of pregnancy and progeny lymphoid tissues were excised during gestation (day 18; GD18) or at 1 or 6 weeks post-partum. The isolated lymphoid cells were analyzed by flow cytometry/immunofluorescence or assessed for function. In Bα P-exposed fetuses, thymic Thy1+ cell levels were decreased (relative to levels in organs of corn oil-exposed dam progeny). In addition, for up to 6 weeks post-birth, CD4+CD8+ (double positive; DP) cells were virtually absent and levels of CD4−CD8− (double negative; DN) cells were consistently at ε 90%. With regard to single positive (SP) cells, CD4+ cell levels were also decreased in tissues at GD18 up through 6 weeks post-birth; CD8+ cell levels were increased, but only in pups at 1-week and 6-weeks post-birth. In 1-week-old progeny, spleen CD8+ cell levels were quantitatively unchanged, though CD4+ levels were reduced 2–4-fold and CD4−CD8− DN levels significantly increased. With respect to TCRs, fetal levels of thymic CD3Vγ3+ and CD3Vγ δ+ cells were decreased; levels of CD3Vαβ cells were only slightly depressed. The latter results contrast sharply with a strong reduction in CD3Vαβ cells in the fetal livers of Bα P-exposed progeny. Interestingly, these livers also strongly evidenced a presence of BαP-7,8-dihydrodiol-9,10-epoxide metabolite. When assessed for any change in function, the CD4+, Thy1+ cells isolated from Bα P-exposed progeny tissues responded weakly (relative to controls) to ConA and in an allogeneic MLR. Taken in totality, the results here strengthen our original hypothesis that BαP can create a favorable milieu for tumor growth progression in progeny of exposed mothers by affecting development of sufficient numbers of functional lymphocytes in the offspring.

HIV-1 Upregulates Intercellular Adhesion Molecule-1 Gene Expression in Lymphoid Tissue of Patients With Chronic HIV-1 Infection

Intercellular adhesion molecule (ICAM)-1 is an adhesion molecule that plays an important role in the transmission of HIV-1 to CD4+ target cells and in the decrease of these cells in lymphoid tissue (LT). Our main objective was to study ICAM-1 expression in LT from HIV-1-infected persons and to correlate this expression with LT viral load and the immunoarchitecture alteration before and after highly active antiretroviral therapy (HAART). Tonsillar LT samples from 16 patients with chronic asymptomatic HIV-1 infection were studied before initiating treatment and after 12 months of HAART. ICAM-1 protein expression was studied by immunohistochemistry in all cases, and ICAM-1 messenger RNA (mRNA) was quantified from frozen tissue in 6 patients using quantitative real-time polymerase chain reaction (PCR). LT viral load was determined by PCR. The LT immunoarchitecture, p24 immunoexpression, and CD4+ cell count were assessed from tissue sections. Before initiating HAART, there was high immunohistochemical ICAM-1 expression in follicular dendritic and endothelial cells and high ICAM-1 mRNA quantification. These findings correlated with a high LT viral load, strong p24 expression, and an effacement of LT immunoarchitecture with a low number of CD4+ cells. After HAART, there was a significant decrease of immunohistochemical and gene ICAM-1 expression. These results correlated with a significant decrease of LT viral load and p24 immunoexpression, a recovery of LT architecture, and a significant increase of CD4+ cells. HIV-1 upregulates ICAM-1 expression in LT. This finding is associated with a marked effacement of LT architecture. HAART produces downregulation of ICAM-1 expression and recovery of LT architecture by reducing LT viral load significantly.

CXCL10 is required for the recruitment of leukocytes responsible for controlling herpes simplex virus-1 infection (43.19)

Abstract The chemokine CXCL10 is among the earliest cytokines produced during nervous system inflammation induced by herpes simplex virus-1 (HSV-1) infection. Current evidence suggests CXCL10 is important in the recruitment of a wide range of leukocytes including CD4 and CD8+ T-cells, macrophages, dendritic, and NK cells. Many of these studies have suggested the function of this chemokine extends beyond simple leukocyte recruitment as CXCL10 is also expressed in primary and secondary lymphoid tissues. To elucidate the role CXCL10 has in generating an effective immune response to viral infection of the nervous system, we have analyzed leukocyte recruitment and effector function in CXCL10 deficient (−/−) mice relative to wild type C57BL6/J, CXCL9 deficient, and CXCR3 deficient mice infected with HSV-1. Our results indicate CXCL10 is critical for the recruitment of NK cells and B220+CD11c+ cells, in a CXCR3-dependent manner. Infiltration of HSV-1 specific CD8+ T-cells into the central nervous system of CXCL10 −/− mice is significantly reduced compared to wild type mice, but CXCL10 expression in lymphoid tissues does not contribute in the generation of HSV-specific CD8+ T-cells. Nervous system restricted expression of CXCL10 restored the homing of HSV-1 specific CD8+ T-cells to wild type levels and partially restored homing of natural killer and conventional dendritic (B220-CD11c+) cells.

Unique Pathology in Simian Immunodeficiency Virus-Infected Rapid Progressor Macaques Is Consistent with a Pathogenesis Distinct from That of Classical AIDS

Simian immunodeficiency virus (SIV) infection of macaques and human immunodeficiency virus type 1 (HIV-1) infection of humans result in variable but generally fatal disease outcomes. Most SIV-infected macaques progress to AIDS over a period of 1 to 3 years, in the face of robust SIV-specific immune responses (conventional progressors [CP]). A small number of SIV-inoculated macaques mount transient immune responses and progress rapidly to AIDS (rapid progressors [RP]). We speculated that the underlying pathogenic mechanisms may differ between RP and CP macaques. We compared the pathological lesions, virus loads, and distribution of virus and target cells in SIVsmE660- or SIVsmE543-infected RP and CP rhesus macaques at terminal disease. RP macaques developed a wasting syndrome characterized by severe SIV enteropathy in the absence of opportunistic infections. In contrast, opportunistic infections were commonly observed in CP macaques. RP and CP macaques showed distinct patterns of CD4(+) T-cell depletion, with a selective loss of memory cells in RP macaques and a generalized (naive and memory) CD4 depletion in CP macaques. In situ hybridization demonstrated higher levels of virus expression in lymphoid tissues (P < 0.001) of RP macaques and a broader distribution to include many nonlymphoid tissues. Finally, SIV was preferentially expressed in macrophages in RP macaques whereas the primary target cells in CP macaques were T lymphocytes at end stage disease. These data suggest distinct pathogenic mechanisms leading to the deaths of these two groups of animals, with CP macaques being more representative of HIV-induced AIDS in humans.

HHV-6 and the immune system: mechanisms of immunomodulation and viral escape

Clinical and experimental evidence indicates that human herpesvirus 6 (HHV-6) can interfere with the function of the host immune system through a variety of mechanisms. Both HHV-6A and B can infect, either productively or nonproductively, several types of immune cells. The primary target for HHV-6 replication, both in vitro and in vivo, is the CD4 + T lymphocyte, a pivotal cell in the generation of humoral and cell-mediated adaptive immune responses. HHV-6A, but not B, also replicates in various cytotoxic effector cells, such as CD8 + T cells, γδ T cells and natural killer cells. In professional antigen-presenting cells like macrophages and dendritic cells, HHV-6 infection is typically nonproductive; yet, it induces dramatic functional abnormalities, including a selective suppression of IL-12, a critical cytokine in the generation of Th1-polarized antiviral immune responses. This and other immunomodulatory effects seem to be mediated by the engagement of the primary HHV-6 receptor, CD46. Moreover, HHV-6 infection results in a generalized loss of CD46 expression in lymphoid tissue, which may lead to an aberrant activation of autologous complement. Additional mechanisms of immunomodulation by HHV-6 include alterations in cell surface receptor expression and cytokine/chemokine production. HHV-6 can also modulate influence responses through the expression of virally-encoded homologs of chemokines and chemokine receptors. By modulating specific antiviral immune responses, HHV-6 can facilitate its own spread and persistence in vivo, as well as enhance the pathogenic effects of other agents, such as human immunodeficiency virus.

Retinoblastoma gene family expression in lymphoid tissues

It appears more and more clear that retinoblastoma (RB) family of proteins represents key molecules in tumour suppression. This family consists of pRb/p105, p107 and pRb2/p130, which participate in a gene regulatory network that governs the cellular response to antimitogenic signals, and whose deregulation constitutes one of the hallmarks of cancer. Irrespective of their structural and biochemical similarities, RB proteins carry out different functional tasks. The expression of RB gene family in the reactive lymphoid tissues again confirms the different role of each member in cell cycle control and differentiation of normal cells. These different functional properties appear to be maintained in tumours lymphoid tissues, where alterations of the RB/p105 gene appear to be relatively rare. In this review, we will summarize the current knowledge about the role of the RB proteins in reactive and neoplastic lymphoid tissue.

Characterization of an interleukin-15 like (IL-15L) gene from zebrafish ( Danio rerio)

In fish, interleukin (IL)-2, IL-21 and IL-15 genes have recently been identified by in-silico cloning. Fish IL-15 gene is similar to counterparts from mammals and other vertebrates. A zebrafish genomic database-search initiated to find IL-2 and IL-21 genes from zebrafish ( Danio rerio) led to the identification of an IL-15 like gene (IL-15L). This gene was cloned by prediction and the transcripts were subsequently cloned by PCR. The predicted translation yielded a 162 amino acid protein with a 42 amino acid-long signal peptide. This protein shared identities of 28.4% to 31.5% with other mammalian and vertebrate IL-2, IL-15 and IL-21 genes. The gene occupies 7.7 kb of the genomic DNA and the coding region spans into four exons and is interrupted by three introns, which is similar to the genomic structure of IL-2 gene. The chromosomal synteny and phylogenetic analyses support our view that this IL-15L gene is specific to teleosts. Furthermore, two alternatively spliced forms have been identified with differential exon usage translating for proteins of 108 and 120 amino acids in length. The analysis of the alternative splicing suggests it may play an important role in regulating the function of this novel gene. Analyses by RT–PCR and in situ hybridization show gene expression in lymphoid tissues like intestine, gills, spleen, pancreas and kidney suggestive of a role in immunity of fish.

Molecular Pharmacological Phenotyping of EBI2: AN ORPHAN SEVEN-TRANSMEMBRANE RECEPTOR WITH CONSTITUTIVE ACTIVITY

Epstein-Barr virus (EBV)-induced receptor 2 (EBI2) is an orphan seven-transmembrane (7TM) receptor originally identified as the most up-regulated gene (>200-fold) in EBV-infected cells. Here we show that EBI2 signals with constitutive activity through Galpha(i) as determined by a receptor-mediated inhibition of forskolin-induced cAMP production and an induction of the serum response element-driven transcriptional activity in a pertussis toxin-sensitive manner. Galpha(s) and Galpha(q) were not activated constitutively as determined by the lack of cAMP production, the lack of inositol phosphate turnover, and the lack of activities of the transcription factors: cAMP response element-binding protein and nuclear factor-kappaB. Immunohistochemistry and confocal microscopy of FLAG- and green fluorescent protein-tagged EBI2 revealed cell-surface expression. A putative N-terminal truncated version of EBI2, delta4-EBI2, showed similar expression and signaling through Galpha(i) as full-length EBI2. By using a 32P-labeled EBI2 probe we found a very high expression in lymphoid tissue (spleen and lymph node) and peripheral blood mononuclear cells and a high expression in lung tissue. Real-time PCR of EBV-infected cells showed high expression of EBI2 during latent and lytic infection, in contrast to the EBV-encoded 7TM receptor BILF1, which was induced during lytic infection. EBI2 clustered with the orphan GPR18 by alignment analysis as well as by close proximity in the chromosomal region 13q32.3. Based on the constitutive signaling and cellular expression pattern of EBI2, it is suggested that it may function in conjunction with BILF1 in the reprogramming of the cell during EBV infection.

Nephrin in human lymphoid tissues.

When nephrin, the protein product of NPHS1, was cloned, it was proposed to be specific for the kidney glomerular podocytes. Recently, however, new reports have emerged verifying additional nephrin expression sites, particularly the insulin-producing beta cells of the pancreas, as well as the central nervous system. In this study, we demonstrate nephrin expression in lymphoid tissues, specifically the tonsil, adenoid and lymph node. Nephrin mRNA expression levels were 4-fold higher in tonsils and adenoids than in thymus or B lymphocytes, and 20-fold higher than in T lymphocytes or monocytes, as shown by quantitative RT-PCR analysis. Anti-nephrin antibodies recognised a specific 165-kDa band in lysates of tonsil and adenoid. In immunofluorescence and immunohistochemichal stainings of adenoid and lymph node sections, nephrin-positive cells were detected in the germinal centres of the lymphoid follicles in a staining pattern typical for interdigitating cells. These results indicate a definite and additional presence of nephrin in lymphoid tissue.

A Novel E3 Ubiquitin Ligase TRAC-1 Positively Regulates T Cell Activation

TRAC-1 (T cell RING (really interesting new gene) protein identified in activation screen) is a novel E3 ubiquitin ligase identified from a retroviral vector-based T cell surface activation marker screen. The C-terminal truncated TRAC-1 specifically inhibited anti-TCR-mediated CD69 up-regulation in Jurkat cells, a human T leukemic cell line. In this study, we show that TRAC-1 is a RING finger ubiquitin E3 ligase with highest expression in lymphoid tissues. Point mutations that disrupt the Zn(2+)-chelating ability of its amino-terminal RING finger domain abolished TRAC-1's ligase activity and the dominant inhibitory effect of C-terminal truncated TRAC-1 on TCR stimulation. The results of in vitro biochemical studies indicate that TRAC-1 can stimulate the formation of both K48- and K63-linked polyubiquitin chains and therefore could potentially activate both degradative and regulatory ubiquitin-dependent pathways. Antisense oligonucleotides to TRAC-1 specifically reduced TRAC-1 mRNA levels in Jurkat and primary T cells and inhibited their activation in response to TCR cross-linking. Collectively, these results indicate that the E3 ubiquitin ligase TRAC-1 functions as a positive regulator of T cell activation.

HIV-1 does not provoke alteration of cytokine gene expression in lymphoid tissue after acute infection ex vivo.

The cytokine response to invading microorganisms is critical for priming the adaptive immune response. During acute HIV infection, the response is disrupted, but the mechanism is poorly understood. We examined the cytokine response in human lymphoid tissue, acutely infected ex vivo with HIV. Lymphoid tissue was cultured either as blocks or as human lymphocyte aggregate cultures (HLAC) of tonsils and lymph nodes. This approach allowed us to examine the effects of HIV on cytokines using distinct culture techniques. In contrast to HLAC, mock-infected tissue blocks displayed a 50- to 100-fold up-regulation of mRNAs for IL-1beta, -6, and -8 in the first 6 days of culture. Parallel increases were also noted at the protein level in the supernatants. Although IL-1beta, -6, and -8 are known to synergistically enhance HIV replication, peak HIV replication (measured as p24 Ag) was similar in tissue blocks and HLAC. Surprisingly, vigorous HIV replication of CXCR4- and CCR5-tropic HIV strains did not result in characteristic mRNA profiles for IL-1beta, -2, -4, -6, -8, -10, -12, -15, IFN-gamma, TNF-alpha, TGF-beta, and beta-chemokines in tissue blocks or HLAC. The increased expression of IL-1beta, -6, and -8 in tissue blocks may approximate clinical situations with heightened immune activation; neutralization of these cytokines resulted in inhibition of HIV replication, suggesting that these cytokines may contribute to HIV replication in certain clinical settings. These results also indicate that different molecular mechanisms govern HIV replication in tissue blocks and HLAC. Prevention of effective cytokine responses may be an important mechanism that HIV uses during acute infection.

Human Oct-1L isoform has tissue-specific expression pattern similar to Oct-2

POU homeodomain proteins are important regulators of ubiquitous as well as tissue-specific transcription. Ubiquitously expressed Oct-1 and tissue-specific Oct-2 proteins are members of the POU family and contain very similar DNA-binding POU domains. While Oct-1 is ubiquitous, Oct-2 is predominantly expressed in B cells, in activated T cells and in nervous system. Oct-1 is involved in regulation of some houskeeping genes—histone H2B, snRNAs as well as in tissue-specific regulation of immunoglobuline gene transcription and of some other genes. Here we report that novel alternatively spliced product of the human Oct-1 gene encode Oct-1L isoform with tissue-specific expression pattern, similar to Oct-2. Oct-1L differ from ubiquitously expressed Oct-1A in 5′-terminal exon (exon 1L). Analysis of nucleotide sequences from Human Genome Data Bank has located exon 1L about 108 kbp downstream ubiquitously expressed exon 1U. Amino terminus of Oct-1L show extensive similarity to amino terminus of Oct-2. We suppose, that Oct-1L may has a specific role in gene expression in lymphoid tissues and brain.

Glucocorticoids Synergistically Enhance NontypeableHaemophilus influenzae-induced Toll-like Receptor 2 Expression via a Negative Cross-talk with p38 MAP Kinase

The recognition of invading microbes followed by the induction of effective innate immune response is crucial for host survival. Human surface epithelial cells are situated at host-environment boundaries and thus act as the first line of host defense against invading microbes. They recognize the microbial ligands via Toll-like receptors (TLRs) expressed on the surface of epithelial cells. TLR2 has gained importance as a major receptor for a variety of microbial ligands. In contrast to its high expression in lymphoid tissues, TLR2 is expressed at low level in epithelial cells. Thus, it remains unclear whether the low amount of TLR2 expressed in epithelial cells is sufficient for mediating bacteria-induced host defense and immune response and whether TLR2 expression can be up-regulated by bacteria during infection. Here, we show that TLR2, although expressed at very low level in unstimulated human epithelial cells, is greatly up-regulated by nontypeable Hemophilus influenzae (NTHi), an important human bacterial pathogen causing otitis media and chronic obstructive pulmonary diseases. Activation of an IKKbeta-IkappaBalpha-dependent NF-kappaB pathway is required for TLR2 induction, whereas inhibition of the MKK3/6-p38alpha/beta pathway leads to enhancement of NTHi-induced TLR2 up-regulation. Surprisingly, glucocorticoids, well known potent anti-inflammatory agents, synergistically enhance NTHi-induced TLR2 up-regulation likely via a negative cross-talk with the p38 MAP kinase pathway. These studies may bring new insights into the role of bacteria and glucocorticoids in regulating host defense and immune response and lead to novel therapeutic strategies for modulating innate immune and inflammatory responses for otitis media and chronic obstructive pulmonary diseases.

Accumulation of DC-SIGN+CD40+ dendritic cells with reduced CD80 and CD86 expression in lymphoid tissue during acute HIV-1 infection.

Dendritic cells (DC) are target cells for HIV-1 and play a key role in antigen presentation and activation of T cells. To characterize interdigitating DC in lymphoid tissue (LT) with regard to maturation, expression of cytokines and co-stimulatory molecules in HIV-1-positive patients. DC were characterized by immunohistochemistry and in situ imaging in LT from patients with acute HIV-1 infection (aHI), antiretroviral treated patients, long-term non-progressors/slow progressors with HIV-1 infection (LTNP/SLP), patients with AIDS, HIV-1-negative controls and patients with acute Epstein-Barr virus (EBV) infection. A significant increase of interdigitating DC expressing CD1a, S-100b, CD83 and DC-SIGN was found in LT from patients with aHI (P < 0.02). The co-stimulatory molecules CD80 and CD86 were, however, only partially upregulated and the complete parafollicular network found in acute EBV infection was not generated, despite increased expression of interleukins 1alpha, 1beta, 12; interleukin 1alpha receptor antagonist; interferon alpha; and CD40 expression. LTNP/SLP and treated aviremic subjects had increased frequency of interdigitating DC, albeit lower than in aHI, and low expression of CD80 and CD86. In contrast, patients with AIDS had fewer DC and reduced cytokine expression in LT. In the early phase of HIV-1 infection, there was a migration of DC to LT comparable to that found in acute EBV infection. The infiltration of DC in LT in acute EBV infection was accompanied by upregulation of CD80 and CD86 expression, which did not occur in aHI. This co-stimulatory defect in aHI may have an impact on the development of HIV-1-specific T cell immunity.

Rhesus macaque and chimpanzee DC-SIGN act as HIV/SIV gp120 trans-receptors, similar to human DC-SIGN

Dendritic cells (DC) have been implicated in the pathogenesis of both human and simian immunodeficiency viruses (HIV and SIV, respectively). The DC-specific HIV-1 trans-receptor DC-SIGN is thought to be essential for viral dissemination by DC. Abundant expression in lymphoid tissues also implies a function for DC-SIGN in chronic HIV-1 infections, in facilitating persistent infection of T cells. We have therefore isolated the rhesus macaque and chimpanzee homologues of DC-SIGN to investigate their function in a primate model. Both rhesus macaque and chimpanzee DC-SIGN are highly similar to the human homologue. Three monoclonal antibodies against human DC-SIGN, AZN-D1, -D2 and -D3, cross-react with rhesus macaque DC-SIGN, whereas AZN-D2 does not cross-react with chimpanzee DC-SIGN. The primate homologues are abundantly expressed in lymphoid tissues such as lymph nodes, as well as in mucosal tissues involved in sexual transmission of HIV-1, and are functionally similar to human DC-SIGN. They have a high affinity for the immunological ligands of DC-SIGN: ICAM-2 and -3. Moreover, both homologues bind the HIV-1 envelope glycoprotein gp120 and therefore can act as a HIV-1 trans-receptor in the same way as human DC-SIGN. These data demonstrate that primate models are suitable to further dissect the role of DC-SIGN in the transmission and pathogenesis of infection with immunodeficiency viruses.

Molecular cloning and characterization of a novel SH3 protein (SLY) preferentially expressed in lymphoid cells

A novel full-length cDNA was isolated from a murine T-cell lymphoma library that has an open reading frame encoding 381 amino acids. The predicted protein (termed SLY) contains a Src homology 3 domain and a sterile α motif, suggesting that it functions as a signaling adaptor protein in lymphocytes. Northern blot and in situ hybridization analysis showed a preferential expression in lymphoid tissues. The sly gene is located on the X-chromosome in close proximity to genes involved in various immune disorders. This is consistent with an additional role of SLY in immune pathology.

B-Myb overexpression results in activation and increased Fas/Fas ligand-mediated cytotoxicity of T and NK cells.

The human B-myb gene encodes a transcriptional regulator that plays an important role in cell cycle progression, differentiation, and survival. To assess the in vivo role of B-myb, we investigated the phenotype of mouse transgenic lines in which B-Myb expression in lymphoid tissues was driven by the LCK proximal promoter. Overexpression of B-Myb had no measurable effect on the subsets of splenic and thymic lymphocytes, but was associated with increased expression of Fas ligand in NK and T cells. B-Myb-overexpressing splenocytes expressed higher IFN-gamma levels and contained higher percentages of cytokine-producing cells than wild-type (wt) splenocytes, as detected by Western blot analysis and ELISPOT assays, respectively. Ex vivo-cultured transgenic thymocytes and splenocytes had decreased survival compared with the corresponding cells from wt mice, possibly dependent on increased expression of Fas ligand. In addition, Fas ligand-dependent cytotoxicity of transgenic T and NK cells was significantly higher than that mediated by their wt counterparts. Together, these results indicate that B-Myb overexpression results in T and NK cell activation and increased cytotoxicity. Therefore, in addition to its well-established role in proliferation and differentiation, B-myb also appears to be involved in activation of NK and T cells and in their regulation of Fas/Fas ligand-mediated cytotoxicity

Gene duplications at the chemokine locus on mouse chromosome 4: multiple strain-specific haplotypes and the deletion of secondary lymphoid-organ chemokine and EBI-1 ligand chemokine genes in the plt mutation.

The murine paucity of lymph node T cell (plt) mutation leads to abnormalities in leukocyte migration and immune response. The causative defect is thought to be a loss of secondary lymphoid-organ chemokine (SLC) expression in lymphoid tissues. We now find that the plt defect is due to the loss of both SLC and EBI-1 ligand chemokine (ELC) expression in secondary lymphoid organs. In an examination of the plt locus, we find that commonly used inbred mouse strains demonstrate at least three different haplotypes. Polymorphism at this locus is due to duplications of at least four genes, three of them encoding chemokines. At least two cutaneous T cell-attracting chemokine (CTACK), three SLC, and four ELC genes or pseudogenes are present in some haplotypes. All haplotypes share a duplication that includes two SLC genes, which demonstrate different expression patterns, a single functional ELC gene, and an ELC pseudogene. The plt mutation represents a deletion that includes the SLC gene expressed in secondary lymphoid organs and the single functional ELC gene, leaving only an SLC gene that is expressed in lymphatic endothelium and an ELC pseudogene. This lack of CCR7 ligands in the secondary lymphoid organs of plt mice provides a basis for their severe abnormalities in leukocyte migration and immune response.

BCL10 Expression in Normal and Neoplastic Lymphoid Tissue: Nuclear Localization in MALT Lymphoma

BCL10 is an apoptotic regulatory molecule identified through its direct involvement in t(1;14)(p22;q32) of mucosa-associated lymphoid tissue (MALT) lymphoma. We examined BCL10 protein expression in various normal tissues and B-cell lymphomas by immunohistochemistry of formalin-fixed and paraffin-embedded tissues using mouse BCL10 monoclonal antibodies. BCL10 protein was expressed in lymphoid tissue but not in 21 various other tissues with the exception of breast. In normal B-cell follicles, the protein was expressed abundantly in the germinal center B cells, moderately in the marginal zone, but only weakly in the mantle zone B cells. Irrespective of their stage of B-cell maturation, BCL10 was predominantly expressed in the cytoplasm. In contrast, each of the four MALT lymphomas with t(1;14)(p22;q32) showed strong BCL10 expression in both the nucleus and cytoplasm. Twenty of 36 (55%) MALT lymphomas lacking the translocation exhibited BCL10 expression in both the nucleus and cytoplasm although at a much lower level, whereas the remaining 16 cases displayed only cytoplasmic BCL10. Unlike MALT lymphoma, both follicular and mantle cell lymphomas generally displayed BCL10 expression compatible to their normal cell counterparts. Our results show differential expression of BCL10 protein among various B-cell populations of the B-cell follicle, indicating its importance in B-cell maturation. The subcellular localization of BCL10 was frequently altered in MALT lymphoma in comparison with its normal cell counterparts, suggesting that ectopic BCL10 expression may be important in the development of this type of tumor.

Expression analysis of the thyrotropin-releasing hormone receptor (TRHR) in the immune system using agonist anti-TRHR monoclonal antibodies

Monoclonal anti-rat thyrotropin-releasing hormone (TRH) receptor (TRHR)-specific antibodies (mAb) were generated by immunization with synthetic peptides of rat TRHR partial amino acid sequences; one (TRHR01) was directed against a sequence (84–98) in the extracellular portion of the rat TRHR reported to be constant among different species, including man, and the second (TRHR02) recognizes the C-terminal region sequence 399–412. In lysates from GH 4C 1 cells, a clonal rat pituitary cell line, both mAb recognize the TRHR in Western blot analysis, and TRHR02 immunoprecipitates the TRHR. Incubation of GH 4C 1 cells with the mAb causes a fluorescence shift in fluorescence-activated cell sorting analysis. The cells were stained specifically by both mAb using immunocytochemical techniques. Furthermore, TRHR01 is agonistic in its ability to trigger Ca 2+ flux, and desensitizes the TRH receptor. We tested for TRHR in several rat organs and found expression in lymphoid tissues. TRHR01 recognizes the human TRHR, and analysis of human peripheral blood lymphocyte and tonsil-derived leukocyte populations showed receptor expression in non-activated and phytohemagglutinin-activated T and B cells.