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PubMed2004

Differential expression of angioregulatory factors in normal and CNV-derived human retinal pigment epithelium.

BACKGROUND: Choroidal neovascularization (CNV) causes loss of vision in age-related macular degeneration (AMD). In CNV, choroidal capillaries penetrate Bruch's membrane and the retinal pigment epithelium (RPE). Angiogenic factors produced by RPE cells are suspected as major contributors to CNV development. We therefore studied the differential expression of angioregulatory factors in normal and CNV-derived RPE. METHODS: Cultures of normal (ARPE-19) and CNV-derived RPE (CNV-RPE) were compared by quantitative PCR. Differential expression was verified on the protein level by immunohistochemistry in tissue samples. RESULTS: The angioregulatory factors VEGF-A, VEGF-B, VEGF-C, Angiopoietin-1 (Ang-1) and Angiopoietin-2, Semaphorin-3A, PEDF, HIF-1, FGF-2, and the receptors VEGF-R2, Neuropilin-1 and Neuropilin-2 were detected in both, ARPE-19 and CNV-RPE. Transcription of PEDF, FGF-2, Neuropilin-2, Ang-1 and Ang-2 was significantly upregulated in CNV-RPE. EphA7, VEGF-R1 and leptin were transcribed exclusively in CNV-RPE and Eph-A7 and VEGF-R1 proteins were present exclusively in CNV specimens. CONCLUSIONS: A set of common factors controlling angiogenesis was detected in both, ARPE-19 cells and CNV-RPE cells. Surprisingly, PEDF and other factors inhibiting angiogenesis are strongly upregulated in CNV-RPE; thus, at least in later stages, the RPE has a potential to control angiogenesis in age-related macular degeneration.

Angiogenic Proteins↗
PubMed2006

Differential expression of surfactant protein A in the nasal mucosa of patients with allergy symptoms.

OBJECTIVE: To characterize surfactant protein A (SP-A) expression in human nasal tissue and correlate differential expression of SP-A with symptoms suggestive of allergic rhinitis. DESIGN: Allergic rhinitis symptom data were prospectively collected in the form of the Rhinitis Symptom Utility Index, the Rhinoconjunctivitis Quality of Life Questionnaire, and a Visual Analog Scale. Immunohistochemical staining for SP-A was performed on resected nasal tissue. Quantitative polymerase chain reaction amplification of the SP-A gene referenced to beta-actin was performed on complementary DNA samples synthesized from total RNA isolates. SETTING: Academic tertiary referral center, department of otolaryngology laboratories. PATIENTS: Twenty-five consecutive patients undergoing nasal surgery. MAIN OUTCOME MEASURES: Immunohistochemical staining of SP-A in human nasal mucosa and submucosa, polymerase chain reaction amplification of SP-A messenger RNA, and rhinitis symptom scores. RESULTS: Immunostaining localized SP-A to the mucosa and submucosal glands in specimens. Quantitative polymerase chain reaction demonstrated correlation between SP-A messenger RNA concentration and the total Rhinitis Symptom Utility Index score (0.51, P = .009) as well as "sneezing over the previous week" (0.40, P = .049), "runny nose over the previous week" (0.55, P = .005), and "sneezing today" (0.47, P = .02). CONCLUSIONS: To our knowledge, this is the first report of SP-A expression in human nasal tissue. Furthermore, the degree of expression correlated with severity of disease as measured by the Rhinitis Symptom Utility Index in patients with allergic rhinitis symptoms.

Adult↗
PubMed1994

Differential expression of two mRNA species indicates a dual function of peripheral myelin protein PMP22 in cell growth and myelination.

Two peripheral myelin protein PMP22 transcripts, CD25 and SR13, have been identified by Northern blot and RNA-polymerase chain reaction (PCR) methods in rat. The CD25 and SR13 mRNA species (each approximately 1.8 kb in size) differ significantly in their 5'-untranslated region (5'-UTR) sequences but encode the same protein. While CD25 mRNA is largely confined to the peripheral nervous system, the SR13 transcript is more ubiquitously expressed in rat tissues. Both transcripts are differentially expressed during postnatal sciatic nerve development. While CD25 expression steadily increases from low levels in neonates up to a maximum at postnatal day 14, SR13 mRNA levels are elevated at birth but decrease throughout adulthood. CD25 and SR13 transcripts are expressed at very low constant levels in developing and adult brain. In degenerating and regenerating segments of injured peripheral nerve changes in CD25 mRNA levels clearly resemble the expression pattern of other myelin genes, whereas expression of SR13 is inversely correlated with the time course of Schwann cell proliferation. In cultured rat meningeal fibroblasts SR13 mRNA expression is strictly growth arrest-specific and independent of forskolin. On the other hand, regulation of CD25 mRNA levels in these cells is more complex with respect to interfering effects of serum and forskolin. In cultured Schwann cells neither CD25 nor SR13 expression is growth arrest-specific. However, both transcript levels are consistently enhanced by forskolin under all conditions of cell growth tested. Expression of CD25 (but not SR13) depends on high Schwann cell density. Our results substantiate the hypothesis that PMP22 serves two biological functions, one related to cell growth (SR13) and another to myelination (CD25).

Animals↗
PubMed2004

Identification of genes differentially expressed in monocyte-derived dendritic cells with 1alpha,25-dihydroxyvitamin D3 using cDNA arrays.

In order to study the molecular mechanism of the inhibitory effect of 1,25-dihydroxyvitamin D(3) on dendritic cells, experiments were performed using Atlas cDNA expression arrays from Clonetech to identify the differentially expressed genes of dendritic cells by 1,25-dihydroxyvitamin D(3). Analysis of cDNA arrays revealed changes in the expression of 9 genes, including those involved in DNA binding and transcription, extracellular cell signaling and communication, intracellular transducers, as well as cell adhesions. The results indicated that a multiple molecular network is involved in the inhibitory role of 1,25-dihydroxyvitamin D(3) on dendritic cells. The Atlas Array technology may facilitate the elucidation of complex pharmacological process of 1,25-dihydroxyvitamin D(3) on dendritic cells.

Calcitriol↗
PubMed2006

Differential expression of toll-like receptor 3 and 5 in ileal pouch mucosa of ulcerative colitis patients.

BACKGROUND AND AIMS: The pathogenesis of pouchitis, major complication after restorative proctocolectomy, and ileal J pouch-anal anastomosis (IPAA) in patients with ulcerative colitis (UC) is still unclear. Changes in intraluminal bacterial colonization and correlated changes of pouch mucosa are thought to play an important role. Toll-like receptors (TLRs) as part of the innate immune system are capable of recognizing bacterial antigens. Their activation can lead to secretion of proinflammatory mediators. In this study, TLR2, 3, 4, and 5 expression profiles in the pouch mucosa of patients with UC and IPAA were analyzed and correlated with pouchitis. MATERIALS AND METHODS: Clinical symptoms, endoscopy, and histology were assessed in 35 patients using the Heidelberg Pouchitis Activity Score to classify patients as either having pouchitis or not. TLR mRNA expression in normal ileal mucosa and pouch mucosa was investigated by performing semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). The results of RT-PCR were associated with the pouchitis score. RESULTS: In the analysis of all patients, TLR3 expression was decreased significantly whereas TLR5 expression was increased significantly in pouch mucosa compared to normal ileal mucosa (p-values 0.0076 and 0.016, respectively). A more detailed analysis upon dividing the patients into patients with and without pouchitis showed decreased TLR3 expression in the pouch mucosa only of patients without pouchitis (p-value=0.0067). TLR5 expression was increased in the pouch mucosa only of patients with pouchitis (p-value=0.023). No differences in TLR2 and 4 expression were found in either group. CONCLUSION: Differential expression of TLR3 and 5 suggests bacterial involvement in the pathogenesis of pouchitis in patients with UC.

Adult↗
PubMed2004

Analysis of transcripts that are differentially expressed in three sectors of the rice root system under water deficit.

Short periods of water deprivation can stimulate the growth of seminal and lateral roots in rice, and inhibit the emergence of adventitious roots. Identification of genes in the different tissues that respond to a water deficit may help us to understand the mechanism underlying root growth under conditions when water is scarce. cDNA-amplified fragment length polymorphism (AFLP) analysis was used to profile gene expression upon imposition of water deficit in three types of root tissue from the upland rice variety Azucena: seminal root tips, lateral root zones and adventitious root primordial zones. In all, 121 unique transcript-derived fragments (TDFs) were cloned, and Northern analysis was carried out for 30 TDFs to confirm their expression patterns. Sixty-six TDFs were differentially expressed in all three root samples. Four (AC2, D6, L22 and T23) were up-regulated by water deficit in seminal root tips and lateral root zones, and down-regulated in adventitious root primordial zones, an expression pattern which reflects the phenotypic changes observed in the different root sectors. In contrast, T17 and T37 showed the opposite expression pattern in Azucena: up-regulation in adventitious roots and repression in the other two zones. Functions could be assigned to five of these six TDFs on the basis of homology: they encode an expansin (T37), a fruit-ripening protein similar to ASR (T23), submergence-induced protein 2A (T17), a dehydrin (D6) and a 9- cis -epoxycarotenoid dioxygenase1 (L22), respectively. AC2 did not show a significant match to any known gene. Northern analysis showed that these six clones exhibited expression patterns that differed between the two cultivars tested (Azucena and the lowland variety IR1552) with respect to regulation by water limitation. Furthermore, T17, T37, D6 and T23 mapped within intervals known to contain QTLs (quantitative trait loci) for root growth in rice under water deficit. These genes may regulate or co-regulate the growth and development of the three root zones in a tissue-specific manner, and may play a role in the processes that underlie the early changes in root architecture under conditions of water deprivation.

Blotting, Northern↗
PubMedDate not supplied

Leishmania (Leishmania) amazonensis: differential expression of proteinases and cell-surface polypeptides in avirulent and virulent promastigotes.

A comparative study of proteolytic enzymes and cell-surface protein composition in virulent and avirulent Leishmania (Leishmania) amazonensis promastigote forms was carried out using one- and two-dimensional dodecyl sulfate sodium-polyacrylamide gel electrophoresis (SDS-PAGE). The surface iodinated protein profiles showed two major polypeptides of 65-60 and 50-47 kDa that were expressed in both virulent and avirulent promastigote forms. However, minor quantitative differences were observed in the cell-surface profile between the avirulent and virulent promastigotes. These included polypeptides of 115, 52, 45, 32, and 25 kDa that were preferentially expressed in the virulent forms. Two-dimensional SDS-PAGE showed an accentuated expression of acidic polypeptides; some of them differentially expressed in the promastigote forms analyzed. Live parasites treated with glycosylphosphatidylinositol (GPI)-specific phospholipase C (PLC) from Trypanosoma brucei and immunoprecipitated with the cross-reacting determinant (CRD) antibody recognized three major polypeptides of 65-60, 52, and 50-47 kDa, hence suggesting that these peptides were anchored to the plasma membrane domains through GPI anchor. Moreover, the polypeptides of 65-60 and 52 kDa were also recognized by the gp63 antiserum. Several metalloproteinase activities were similar in both virulent and avirulent promastigote forms, whereas cysteine proteinase activities, sensitive to E-64, were preferentially expressed in virulent promastigotes. These results suggest that cell-surface polypeptides and intracellular cysteine proteinases might play an important role in the virulence of L. (L.) amazonensis.

Animals↗
PubMed2001

Differentially expressed genes in zona reticularis cells of the human adrenal cortex.

The zona reticularis (ZR) cell in the human adrenal cortex is responsible for the secretion of dehydroepiandrosterone, but its biology, origin, and putative decrease in number during aging are poorly understood. In the present experiments, we investigated to what extent ZR and zona fasciculata (ZF) cells differ in patterns of gene expression. Both cell types were purified by microdissection from adult adrenal cortex specimens. After a brief period in culture, RNA was harvested from the cells and used to prepare radioactively labeled probes following amplification by PCR. Probes were used in hybridizations of arrays of cDNAs on nylon membranes (PCR products or plasmids obtained from an adrenal cDNA library). Analysis of hybridization intensities showed that 17 of the 750 genes studied differed in expression by more than 2-fold. Several genes expressed at higher levels in ZR cells encode components of the major histocompatibility complex or enzymes involved in peroxide metabolism. Members of the tubulin gene family were expressed at higher levels in ZF cells. Differential expression of four of the genes was confirmed by Northern blotting. These differences show that although ZR and ZF cells are similar in gene expression, ZR cells have a gene expression pattern related to the unique biology of this cell type.

Adult↗
PubMed1998

Early differential expression of two glutaminase mRNAs in mouse spleen after tumor implantation.

The influence of progressive tumor growth on phosphate-activated glutaminase (PAG) expression in splenocytes from mice bearing Ehrlich ascites carcinoma cells was investigated. Implantation of Ehrlich ascites tumor cells in the peritoneal cavity of mice led to a 2.3-fold stimulation of spleen PAG activity 48 h later. Four days after tumor implantation the glutaminase activity had returned to nearly basal value and remained at this level throughout the tumor development. Northern blot analysis indicated that two species of glutaminase mRNA were expressed in the spleen, which showed a differential expression pattern during the first 2 days after tumor implantation. The abundance of the transcript of higher electrophoretic mobility (approximately 3 kb) constantly increased over the first 2 days of tumor growth. The mRNA of lower electrophoretic mobility (approximately 6 kb) peaked at 12 h after tumor implantation and returned to control values at 48 h. These results demonstrate that tumor has the capability of altering glutaminase expression in the host spleen.

Animals↗
PubMed2002

Differential expression of the CB2 cannabinoid receptor by rodent macrophages and macrophage-like cells in relation to cell activation.

An in vitro model of multi-step activation, in which cells of macrophage lineage are driven sequentially through inflammatory, primed, and fully activated states, was employed to assess for cannabinoid receptor expression. Murine and rat peritoneal macrophages, murine RAW264.7 and P388D, macrophage-like cells, and neonatal rat brain cortex microglia expressed the cannabinoid receptor type 2 (CB2) differentially in relation to cell activation. The CB2 was undetectable in resident peritoneal macrophages, present at high levels in thioglycolate-elicited inflammatory and interferon gamma (IFNgamma)-primed peritoneal macrophages, and detected at significantly diminished levels in bacterial lipopolysaccharide (LPS)-activated peritoneal macrophages. A comparable pattern of differential expression of the CB2 was noted for murine macrophage-like cells and neonatal rat brain cortex microglia. The cannabinoid receptor type 1 (CB1) was not detected in peritoneal macrophages or murine macrophage-like cells regardless of cell activation state but was present in neonatal rat microglia at low levels. These results indicate that levels of the CB2 in cells of macrophage lineage undergo major modulatory changes in relation to cell activation. Furthermore, since inflammatory and primed macrophages express the highest levels of CB2, the functional activities of macrophages when in these respective states of activation may be the most sensitive to the action of cannabinoids.

Animals↗
PubMed2000

Identification of novel hypoxia dependent and independent target genes of the von Hippel-Lindau (VHL) tumour suppressor by mRNA differential expression profiling.

The von Hippel-Lindau tumour suppressor gene (VHL) targets hypoxia inducible factor (HIF)-alpha subunits for ubiquitin dependent proteolysis. To better understand the role of this and other putative pathways of gene regulation in VHL function we subjected mRNA from VHL defective renal carcinoma cells and transfectants re-expressing a wild type VHL allele to differential expression profiling, and analysed VHL target genes for oxygen regulated expression. Among a group of newly identified VHL target genes the majority but not all were regulated by oxygen, indicating that whilst dysregulation of the HIF system makes a dominant contribution to alterations in transcription, VHL has other influences on patterns of gene expression. Genes newly defined as targets of the VHL/hypoxia pathway (conditionally downregulated by VHL in normoxic cells) include aminopeptidase A, collagen type V, alpha 1, cyclin G2, DEC1/Stra13, endothelin 1, low density lipoprotein receptor-related protein 1, MIC2/CD99, and transglutaminase 2. These genes have a variety of functions relevant to tumour biology. However, not all are connected with the promotion of tumour growth, some being pro-apoptotic or growth inhibitory. We postulate that co-ordinate regulation as part of the HIF pathway may explain this paradox, and that evolution of anti-apoptotic pathways may be required for tumour growth under VHL-dysregulation. Our results indicate that it will be necessary to consider the effects of abnormal activity in integral regulatory pathways, as well as the effects of individual genes to understand the role of abnormal patterns of gene expression in cancer.

Carcinoma, Renal Cell↗
PubMed1995

Differential expression of human Fas mRNA species upon peripheral blood mononuclear cell activation.

Human Fas/Apo-1 is a cell-surface protein that mediates apoptosis upon ligation with Fas ligand. The gene lies on the long arm of chromosome 10, consists of nine exons, and spans more than 26 kb of DNA. We previously reported the presence of a Fas variant mRNA, designated as Fas delta TM, in human peripheral blood mononuclear cells. Fas delta TM is generated by alternative splicing of the intact exon 6, which encodes the Fas transmembrane domain. In the present study, we describe three novel forms of Fas mRNA that are generated by alternative splicing of exons 3, 4, 6 and 7. These three mRNA variants undergo a frameshift and produce truncated polypeptides because of the appearance of a stop codon in the altered open reading frame. On activation of the peripheral blood mononuclear cells, a decreased expression of alternatively spliced Fas mRNA species correlated with increased cell-surface expression of Fas. These results suggest that differential expression of alternatively spliced Fas mRNAs may play a role in regulation of Fas function via regulation of the production of the membrane-bound and the soluble, secreted Fas protein products.

Alternative Splicing↗
PubMed1984

Transformation properties of type 5 adenovirus mutants that differentially express the E1A gene products.

Type 5 adenovirus mutants that differentially express E1A 13S, 12S, or 9S mRNAs were constructed to study the role of their gene products in transformation. H5dl520 expresses the 243-amino-acid (AA) protein encoded in the 12S mRNA but not the 13S mRNA-encoded 289-AA protein. This mutant transformed both cloned rat embryo fibroblast (CREF) cells and baby rat kidney (BRK) cells at a frequency 40-100 times greater than did wild-type viruses. In addition, all of the foci produced were fibroblastic and grew very slowly at 32 degrees C. In contrast, H5dl21, which was mutated so that only the 54-AA protein encoded by the 9S mRNA was synthesized, did not transform either cell type. DNA transfection studies with plasmids from which these mutants were constructed demonstrated that the differences in transformation frequencies were not as marked. The plasmid pD1/D2, which directs the synthesis of the 54-AA protein only, was found to transform baby rat kidney cells at low frequency, provided the gene was linked to a fragment from the simian virus 40 genome containing the transcriptional enhancer element.

Adenoviruses, Human↗
PubMed2001

Differential expression of Rab3 isoforms in high- and low-secreting mast cell lines.

The expression of several isoforms of the small-molecular-weight Rab3 GTP-binding proteins is a characteristic feature of all cell types undergoing regulated exocytosis, in which Rab3 proteins are considered to regulate the assembly/disassembly of a fusion complex between granule and plasma membrane in a positive and negative manner through interaction with effector proteins. The pattern of Rab3 protein expression may, therefore, provide a subtle means of regulating exocytosis. To investigate the relationship between Rab3 expression and secretory activity, we assessed the differential expression of individual Rab3 proteins in high- and low-secreting clones of the rat basophilic (RBL) cell line. mRNAs for Rab3 isoforms (a-d) were analyzed by constructing cDNA libraries of high- and low-secreting RBL clones. The relative abundance of mRNAs for Rab3 isoforms was initially determined from the clonal frequency of corresponding cDNA clones. RT-PCR using isoform-specific primers was successfully applied to the quantitation of Rab3a mRNA. The presence of individual Rab3 proteins was revealed by SDS-PAGE and immunoblotting, and also by in situ immunofluorescence confocal microscopy. We present evidence that Rab3a and Rab3c are expressed at high levels in the low-secreting variant, while Rab3d is predominant in the high secretor. Levels of the Rab3 effector proteins, Rabphilin and Noc2, are similar in both RBL cell lines. Subcellular fractionation of unstimulated high and low secretor RBL clones revealed that in both cell types Rab3a has a cytoplasmic location while Rab3d is present in a membrane/organelle fraction containing secretory vesicles. Differences in the pattern of expression of Rab3 isoforms in the two RBL cell lines and their localisation may influence the secretory potential. Furthermore, the presence of Rab3 and effector proteins indicates that the mechanism for regulated exocytosis in cells of mast cells/basophil lineage appears similar to that in pre-synaptic vesicles and pancreatic beta-cells.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Complementary DNA arrays identify CD63 tetraspanin and alpha3 integrin chain as differentially expressed in low and high metastatic human colon carcinoma cells.

SUMMARY: Malignant tumor cell invasion is determinant for metastasis to occur. E2 and C5 colon carcinoma cells that were derived from the parental Lovo line and that differ experimentally in spontaneous metastatic ability have been monitored for gene expression by cDNA arrays. Among genes found differentially expressed, the CD63 tetraspanin, not previously recognized in colon cancer progression, and the alpha3 integrin chain were both up-regulated in low metastatic E2 cells and were analyzed for their functional role using adhesion, migration, and invasion assays. Cell surface expression of CD63 and alpha3 integrin was about 2-fold higher in E2 than in C5 cells and confocal microscopy showed that CD63 and alpha3 integrin colocalized evenly on C5 cells whereas they concentrated at elongated tips of the low-metastatic more substrate-adhesive E2 cells. Antibody-interference experiments identified laminin-5 (LN-5) as a ligand interacting with the alpha3beta1/CD63 complex. Substrate-immobilized anti-CD63 antibodies enhanced tumor cell migration and invasion and induced prominent cell surface protrusions that were repressed by the PI3-kinase LY294002 inhibitor. Our results suggest that changes in the expression of surface CD63 and alpha3beta1 integrin interacting with LN-5 could affect migratory signals and the progression of the metastatic disease.

Antibodies, Blocking↗
PubMed2006

Differential expression and localization of early light-induced proteins in Arabidopsis.

The early light-induced proteins (Elips) in higher plants are nuclear-encoded, light stress-induced proteins located in thylakoid membranes and related to light-harvesting chlorophyll (LHC) a/b-binding proteins. A photoprotective function was proposed for Elips. Here we showed that after 2 h exposure of Arabidopsis (Arabidopsis thaliana) leaves to light stress Elip1 and Elip2 coisolate equally with monomeric (mLhcb) and trimeric (tLhcb) populations of the major LHC from photosystem II (PSII) as based on the Elip:Lhcb protein ratio. A longer exposure to light stress resulted in increased amounts of Elips in tLhcb as compared to mLhcb, due to a reduction of tLhcb amounts. We demonstrated further that the expression of Elip1 and Elip2 transcripts was differentially regulated in green leaves exposed to light stress. The accumulation of Elip1 transcripts and proteins increased almost linearly with increasing light intensities and correlated with the degree of photoinactivation and photodamage of PSII reaction centers. A stepwise accumulation of Elip2 was induced when 40% of PSII reaction centers became photodamaged. The differential expression of Elip1 and Elip2 occurred also in light stress-preadapted or senescent leaves exposed to light stress but there was a lack of correlation between transcript and protein accumulation. Also in this system the accumulation of Elip1 but not Elip2 correlated with the degree of PSII photodamage. Based on pigment analysis, measurements of PSII activity, and assays of the oxidation status of proteins we propose that the discrepancy between amounts of Elip transcripts and proteins in light stress-preadapted or senescent leaves is related to a presence of photoprotective anthocyanins or to lower chlorophyll availability, respectively.

Arabidopsis↗
PubMed2003

IDEG6: a web tool for detection of differentially expressed genes in multiple tag sampling experiments.

Here we present a novel web tool for the statistical analysis of gene expression data in multiple tag sampling experiments. Differentially expressed genes are detected by using six different test statistics. Result tables, linked to the GenBank, UniGene, or LocusLink database, can be browsed or searched in different ways. Software is freely available at the site: http://telethon.bio.unipd.it/bioinfo/IDEG6_form/, together with additional information on statistical methodologies.

Database Management Systems↗
PubMed1987

Differential expression of Ia antigens by rheumatoid synovial lining cells.

The differential expression of Ia antigens was studied in freshly isolated rheumatoid nonlymphoid synovial lining cells (SLC) and rheumatoid synovial fibroblast cell lines cultured in the presence of Interferon-gamma, using a large panel of anti-Ia reagents with monomorphic or polymorphic specificities. All the HLA-DR or -DQ specificities detectable on the corresponding peripheral blood B cells were also expressed in freshly isolated SLC. However, in all instances, the number of DR-positive SLC exceeded the percentage of cells expressing DQ antigens. In addition, the epitope expression of Ia antigens varied within the DR or DQ populations of Ia molecules as revealed by polymorphic reagents. Double-label experiments or using the ingestion of Latex particles as a marker demonstrated that the synovial macrophages (type I SLC) primarily bear the DR+DQ+ phenotype, while there is an additional population of nonphagocytic SLC (previously termed type II SLC) that has a DR+ and monocyte marker negative phenotype but did not have detectable levels of DQ antigens as analyzed by both fluorescence microscopy and cell sorter analysis. This latter population frequently had a morphology showing dendritic processes and rapidly lost the expression of Ia antigens upon culture. Cells with a similar, primarily DR+ phenotype were readily obtained in synovial fibroblast cultures after treatment with Interferon-gamma. These data suggest that there are two populations of Ia+ synovial lining cells: the synovial macrophages (type I cells) with the DR+DQ+ phenotype, and cells probably related to fibroblasts with a DR+ phenotype without detectable DQ antigens (type II cells). The fact that the latter phenotype could be induced by Interferon-gamma treatment of cultured synovial fibroblasts suggests that this mediator may have a similar role in vivo in the activation of certain synovial cell populations.

Arthritis, Rheumatoid↗