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A pathway for association of receptors, adaptors, and actin during endocytic internalization.

In budding yeast, many proteins involved in endocytic internalization, including adaptors and actin cytoskeletal proteins, are localized to cortical patches of differing protein composition. Using multicolor real-time fluorescence microscopy and particle tracking algorithms, we define an early endocytic pathway wherein an invariant sequence of changes in cortical patch protein composition correlates with changes in patch motility. Three Arp2/3 activators each showed a distinct behavior, suggesting distinct patch-related endocytic functions. Actin polymerization occurs late in the endocytic pathway and is required both for endocytic internalization and for patch disassembly. In cells lacking the highly conserved endocytic protein Sla2p, patch motility was arrested and actin comet tails associated with endocytic patch complexes. Fluorescence recovery after photobleaching of the actin comet tails revealed that endocytic complexes are nucleation sites for rapid actin polymerization. Attention is now focused on the mechanisms by which the order and timing of events in this endocytic pathway are achieved.

Actins↗

AC133 antigen as a prognostic factor in acute leukemia.

AC133 is a novel 5-transmembrane antigen present on a CD34((bright)) subset of human hematopoietic stem cells (HSCs) and it is also expressed on the subset of CD34 positive (CD34(+)) leukemias. But the clinical significance of AC133 expression on leukemic blasts is not yet known. We investigated the expression of AC133 antigen on blast cells of acute leukemia. Forty-one cases of acute leukemia were examined for expression of AC133, CD34, and other antigens using multicolor flow-cytometry. Samples were considered positive if at least 20% of the cells specifically stained with monoclonal antibodies (MoAbs) revealed a higher fluorescence intensity compared to cells of corresponding negative control samples (=20% cut-off level). 14/36 (38.9%) acute myelogenous leukemia (AML) samples and 6/20 (30%) acute lymphoblastic leukemia (ALL) samples were positive for AC133, the difference was not significant. All AC133 positive (AC133(+)) leukemias expressed CD34, whereas 13 of 33 CD34(+) leukemias were negative for AC133, and AC133(+)/CD34(-) leukemia was not found. Expression rates of CD31, CD62L, CD62E, CD105 and CD144 were significantly higher in AC133(+) leukemia compared to those of AC133(-) leukemia (P=0.045, P<0.001, P<0.001, P<0.001, P=0.003, respectively), but bcl-2, CXCR-1, CXCR4, VLA-4, CD106 expression rates were not significantly different between AC133(+) and AC133(-) leukemias. None of the clinical prognostic markers such as age, hemogram, lactate dehydrogenase, and chromosomal aberration were significantly different between AC133(+) and AC133(-) leukemias. CR rates of AC133(+) AML and AC133(-) AML were not significantly different, although there was a trend toward higher CR rates in AC133(-) AML (18/22[81.8%] AC133(-) AML versus 9/14[64.3%] AC133(+) AML), but the 1-year relapse rate of AC133(+) AML was significantly higher than that of AC133(-) AML (8/9 (88.9%) versus 7/19 (36.8%), P=0.016). Median disease-free survival (DFS) times of AC133(+) and AC133(-) AML were significantly different (11 and 18 months, respectively, P=0.006), although overall survival (OS) times were not significantly different (AC133(+) 15 months versus AC133(-) 20 months, respectively, P=0.06). Similar results regarding clinical outcomes were found when AC133(+)/CD34(+) and AC133(-)/CD34(+) were analyzed separately, but the difference did not attain statistical significance. In ALL, 9/11 (81.8%) AC133(-) and 2/4 (50%) AC133(+) cases achieved CR, but the difference was not significant. Four of 11 AC133(-) ALL (36.4%) and 2 of 3 AC133(+) ALL (66.7%) relapsed within 1 year. In survival analysis, median DFS time and OS time of the AC133(+) group were 7 and 18 months, respectively, and these were not significantly different from those of the AC133(-) group (median DFS 15, OS 22 months, respectively). Our results demonstrate that AC133 expression in AML blasts is associated with poor clinical outcomes in terms of higher early relapse and shorter disease-free survival, suggesting that the AC133 antigen might provide the prognostic stratification of acute leukemia. However, to verify the effect of AC133 expression on the therapeutic outcomes of adult acute leukemia, further study including more cases is needed.

AC133 Antigen↗

Latanoprost, a prostaglandin analog, for glaucoma therapy. Efficacy and safety after 1 year of treatment in 198 patients. Latanoprost Study Groups.

PURPOSE: To determine efficacy and safety of latanoprost, a prostaglandin analog for glaucoma, during 1 year of treatment. METHODS: After baseline measurements, 0.005% latanoprost was topically applied once daily for 12 months in patients from Scandinavia, the United Kingdom, and the United States who had elevated intraocular pressure (IOP). Diagnoses included ocular hypertension, chronic open-angle glaucoma, exfoliation syndrome, and pigment dispersion syndrome. Treatment was masked for the first 6 months and open-label during the second 6 months. RESULTS: Of the 272 patients initially enrolled, withdrawals were due to inadequate IOP control (1%), increased iris pigmentation (5%), other ocular problems (3%), systemic medical problems (3%), and nonmedical reasons (14%). Latanoprost significantly (P < 0.0001) reduced diumal IOP from 25.3 +/- 3.0 mmHg (mean +/- standard deviation) at baseline to 17.4 +/- 2.7 mmHg (32% reduction) at 12 months in the 198 patients who completed 1 year of treatment. The IOP reduction was maintained at a consistent level throughout the 12 months without evidence of drift, and was not affected by sex, age, race, or eye color. Overall, latanoprost caused a possible or definite increase in iris pigmentation in 12% of the 272 patients, all of whom had multicolored irides at baseline. One half of these patients with increased pigmentation withdrew before completing 1 year of therapy. Visual field, optic disc cupping, visual acuity, refractive error, conjunctival hyperemia, aqueous flare, anterior chamber cellular response, lens examination, blood pressure, heart rate, blood tests, and urinalysis were not appreciably altered. CONCLUSION: Latanoprost safely and effectively reduces IOP for 1 year in patients of diverse nationalities, providing further evidence for its usefulness in chronic glaucoma therapy.

Administration, Topical↗

Pathway tracing using biotinylated dextran amines.

Biotinylated dextran amines (BDA) are highly sensitive tools for anterograde and retrograde pathway tracing studies of the nervous system. BDA can be reliably delivered into the nervous system by iontophoretic or pressure injection and visualized with an avidin-biotinylated HRP (ABC) procedure, followed by a standard or metal-enhanced diaminobenzidine (DAB) reaction. High molecular weight BDA (10 k) yields sensitive and exquisitely detailed labeling of axons and terminals, while low molecular weight BDA (3 k) yields sensitive and detailed retrograde labeling of neuronal cell bodies. The detail of neuronal cell body labeling can be Golgi-like. BDA tolerates EM fixation and processing well and can, therefore, be readily used in ultrastructural studies. Additionally, BDA can be combined with other anterograde or retrograde tracers (e.g. PHA-L or cholera toxin B fragment) and visualized either by multi-color DAB multiple-labeling - if permanent labels are desired, or by using multiple simultaneous immunofluorescence - if fluorescence viewing is desired. In the same manner, BDA pathway tracing and neurotransmitter immunolabeling can be combined. Note that BDA pathway tracing can also be combined with anterograde or retrograde labeling with fluorescent dextran amines, if one wishes to exclusively use tracers with the favorable transport properties and sensitivities of dextran amines. In this case, the BDA can be visualized together with the fluorescent dextran amines using fluorescence labeling for the BDA, or the fluorescent dextran amines can be visualized together with the BDA by multicolor DAB labeling via immunolabeling of the fluorescent dextran amines using anti-fluorophore antisera. BDA is, thus, a flexible and valuable pathway tracing tool that has gained widespread popularity in recent years.

Animals↗

Analysis of monoclonal antibodies reacting with molecules expressed on gammadelta T-cells.

Twenty-six monoclonal antibodies (mAbs) selected after the first round of analysis in the Third International Swine Workshop were grouped with additional mAbs from the first and second workshops and mAbs under study for further evaluation. Preparations of peripheral blood leukocytes were used in single and multicolor flow cytometric (FC) analyses. Six mAbs did not react with gammadelta T-cells. Two were negative for all tested specificities. Seven mAbs recognized molecules expressed on gammadelta T-cells that were not lineage restricted. One of these from the first workshop (2B11) yielded a pattern of labeling identical to a mAb under study (PGB73A). Ten mAbs were characterized in previous workshops and known to react with the gammadelta TCR or molecules expressed on subsets of gammadelta T-cells. One belonged to SWC4, two to SWC5, and one to SWC6. Two mAbs from the second workshop recognized a molecule or molecules expressed on subsets of gammadelta T-cells. A new mAb (PPT16) added late to the workshop following a request by the workshop chairs appeared to recognize a determinant expressed on the gammadelta TCR/CD3 molecular complex.

Animals↗

Lymphocyte populations and adhesion molecule expression in bovine tonsils.

Bovine tonsils are mucosal-associated lymphoid tissue (MALT) located at the entry of the pharynx where both inhaled and ingested antigens can induce an immune response. This study was conducted to determine the lymphocyte populations and adhesion molecule expression in the palatine tonsil (PT) and pharyngeal tonsil (PhT) of adult cattle and compare them with typical MALT (discrete Peyer's patches, PP) and a peripheral lymph node (parotid lymph node, PLN). The distribution of various lymphocyte subsets was determined in situ by immunofluorescence, and their proportions were determined by multicolor flow cytometry. The tonsils were similar to PP in the proportions of B- and T-cells (25-32% T-cells, 39-45% B-cells), and T cell subpopulations (CD4, CD8, and gammadelta). The PP contained the highest proportion of memory T-helper cells with beta7 integrin (30.3%+/-5.4), the tonsils intermediate (PT: 19.8%+/-4.4 and PhT: 19.7%+/-4.9), and the PLN had the lowest proportion (15.4%+/-3.1). The opposite relationship was observed with CD62L on naïve T- helper cells as PP had the lowest proportion (14.2%+/-6.4), the tonsils intermediate (PT: 17.4%+/-2.5 and PhT: 24.3%+/-7.3), and the PLN the highest proportion (45.3%+/-6.5). MAdCAM-1 was highly expressed in the high endothelial venules (HEV) of PP, with variable and weak expression in the tonsils and PLN. PNAd, on the other hand, was highly expressed in HEV of tonsils and PLN, and weakly expressed in the PP. These results indicate that the bovine tonsils share characteristics with both PP and PLN. The alpha4beta7/MadCAM-land CD62L/PNAd interaction may be involved in lymphocyte migration to the tonsils, but it is likely that other adhesion molecules participate as well. Similarities between the human and bovine tonsils suggest that cattle may provide a good model to study the role of the tonsil in the respiratory immune response.

Animals↗

Deletion of 16q11 is a recurrent cytogenetic aberration in acute myeloblastic leukemia during disease progression.

Abnormalities of chromosome 16 other than inv(16)(p13q22), t(16;16)(p13;q22), and del(16)(q22) have not been fully characterized in acute myeloblastic leukemia (AML) and myelodysplastic syndrome (MDS). We report here the first case of AML with del(16)(q11) as a sole abnormality. A 53-year-old woman was initially diagnosed as MDS, refractory anemia with excess of blasts in transformation with normal karyotype. After sixteen months, the disease progressed to overt AML-M1. Myeloblasts were positive for CD13, CD33, and CD34, but negative for HLA-DR. Chromosome analyses of the bone marrow cells showed 46,XX,del(16)(q11) in all metaphase spreads. Multicolor spectral karyotyping also confirmed that del(16)(q11) was not derived from a cryptic translocation, but a simple deletion. Our results, together with three previously reported cases, suggest that del(16)(q11) may be one of the recurrent aberrations in AML and that it could be associated with clonal evolution or disease progression.

Adolescent↗

Spectrum of genetic changes in gastro-esophageal cancer cell lines determined by an integrated molecular cytogenetic approach.

Adenocarcinomas arising around the gastro-esophageal junction (GEJ) are highly malignant, and their incidence has risen rapidly in the last decades. Cell lines are the basic in vitro system for functional and therapeutic studies in GEJ tumors, but only a small number of cell lines are currently available, and none of them has been fully karyotyped. We analyzed 5 GEJ tumor cell lines using a combination of 24-color fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH) and genomic microarrays. Using CGH we demonstrated that these cell lines present imbalances similar to those we had previously observed in primary GEJ tumors, namely gains on 1q, 7q, 8q, 17q, 19q, 20, and X, and losses on 3p, 4, 5q, 9p, 18q, and 21. Multicolor FISH karyotyping revealed multiple structural rearrangements involving chromosomes 1, 5, 6, 7, 8, 9, 13, 17, 18, and 22. Rearrangements of chromosome 8 involved 10 different chromosomes, while rearrangements of chromosome 17 involved 5. Different rearrangements resulted in imbalances of similar chromosome regions, suggesting that similar genomic imbalances are constitutively important but are achieved through different pathways. The use of a commercially available genomic array excluded TOP2A (17q), and MYBL2, PTPT1, CSE1L, and ZNF217 (20q) as candidate genes for frequently amplified areas on these chromosomes, and contributed to refining the limits of chromosome regions involved in genomic imbalances.

Adenocarcinoma↗

Multiple telomeric aberrations in a telomerase-positive leukemia patient.

Bone marrow samples from a pancytopenia/leukemia patient were routinely analyzed at first and second admission. At the first presentation, the karyotype was normal, whereas 17 months later several chromosome aberrations were recognized including presumed additions to the short arms of chromosomes 1 and 16 in all cells, and numerous other aberrations in subpopulations of cells. From the predominance of aberrations at chromosome ends, we suspected insufficient telomere maintenance as an underlying mechanism behind the karyotype changes, in particular as an interstitial deletion in the region harboring the gene for the RNA component (hTERC) of the telomerase enzyme was also noticed; however, while molecular cytogenetic investigation confirmed the terminal aberrations, we found the malignant cells positive for telomerase activity and the presence of an hTERC gene on both chromosomes 3. A presumed chromosome 1 addition turned out to reflect an amplification of a tandemly repeated sequence element. Labeling of multiple tandem repeat sequences in situ by a novel multicolor primed in situ hybridization showed no evidence of instability of other repeated DNA elements.

Adult↗

Unusual karyotype aberrations involving 2p12, 3q27, 18q21, 8q24, and 14q32 in a patient with non-Hodgkin lymphoma/acute lymphoblastic leukemia.

The t(2;18)(p12;q21), known as a rare variant of the t(14;18)(q32;q21), together with t(3;14)(q27;q32), t(8;15)(q24;q22) and two other unusual translocations involving chromosomes 6, 9, 12, and 13, were demonstrated in the bone marrow cells of a 70-year-old male with suspected non-Hodgkin lymphoma/acute lymphoblastic leukemia. The complex chromosomal aberrations were identified by chromosome banding analysis and by fluorescence in situ hybridization (FISH) with whole chromosome painting probes, centromere-specific alpha-satellite probes, and probes specific for genomic sequences of some likely to be involved candidate genes. Several but not all of the chromosomal aberrations could be proved by multicolor FISH. Possible mechanisms leading to this unusual karyotype commonly associated with different histologic lymphoma subtypes and their prognostic implications are discussed.

Aged↗

Blastoid mantle cell lymphoma: evidence for nonrandom cytogenetic abnormalities additional to t(11;14) and generation of a mouse model.

Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32), which is associated with cyclin D1 hyperexpression and a poor prognosis. MCL cases have been shown to progress to a more aggressive disease but the molecular events responsible of this phenomenon have not been determined. We have established two cell lines from the pleural effusions of two patients with MCL that we have used for further cytogenetic characterization to better define the incidence and nature of secondary chromosome abnormalities using multicolor fluorescence in situ hybridization, whole chromosome paint, and specific probes. Both cell lines grew independently without growth factors. Using CCND1/IGH-specific probes, patient UPN1 was found to have a masked t(11;14). Numerous and complex chromosomal abnormalities were found in both cell lines affecting chromosomes 2, 8, 13, 18, 22, X, and Y. These abnormalities included 8p losses, suggesting the presence of an anti-oncogene in this region, rearrangements of 8q24, MYC gene, and translocations involving 8, X, and Y chromosomes, which might be significant in the pathogenesis of MCL progression. The use of the cell lines (UPN1) allowed us to generate a mouse model of human MCL, mimicking a disseminated lymphoma and leading to the death of the animals in 4 weeks. This blastoid MCL model could be of major interest to determine molecular events involved in MCL progression, allowing isolation of involved genes and their functional characterization, and to study the effects of new chemotherapy regimens in mouse models.

Animals↗

Cytogenetic and molecular analysis of an unusual case of acute promyelocytic leukemia with a t(15;17;17)(q22;q23;q21).

We present a 52-year-old female with a clinical history of acute myelocytic leukemia, probable acute promyelocytic leukemia (APL). Flow cytometry results were somewhat unusual. Specifically, the promyelocytic population showed partial positivity for antigens not usually expressed in APL (HLA-DR and CD117). The interpretation of these results was that the abnormal population contained a proportion of very early promyeolocytes that had not completely lost all their "precursor" antigens. Cytogenetic analysis of a bone marrow aspirate showed a t(15:17;17)(q22;q23;q21) in all cells analyzed. Fluorescence in situ hybridization (FISH) analysis using the PML-RARA DNA probe showed a positive signal pattern (fusion) in 100% of 200 total interphase and metaphase cells examined, confirming the presence of the PML-RARA rearrangement. Multicolor FISH, which produces 24 colors to differentiate all chromosomes in a single hybridization, was applied. This study confirmed the cytogenetic interpretation of the rearrangement. No material from any other chromosome was detected on the second smaller derivative chromosome 17. Additional studies using the RARA(17q21) break-apart DNA FISH probe showed that 17q21 (RARA) was not rearranged on the derivative chromosome 17 that received the q22-->qter segment from chromosome 15. The RARA locus on the smaller derivative 17 was the allele involved in the fusion in this three-way rearrangement. The signal pattern was consistent in 100% of interphase and metaphase cells scored. This unusual t(15;17;17) prompted us to investigate further using reverse-transcription polymerase chain reaction with primers from the 3' and 5' regions of both the RARA and PML loci. These studies showed that the PML-RARA fusion was present, but the complementary fusion RARA-PML, which is usually detectable, was absent. The patient is responding well to standard treatment protocols.

Chromosomes, Human, Pair 15↗

Telomeric fusion as a mechanism for the loss of 1p in meningioma.

Characteristic cytogenetic aberrations are found in the various histopathological designations of meningioma. These aberrations range from the loss of 22q in histologically benign tumors to complex hypodiploid karyotypes in atypical and malignant tumors. This progression is characterized by increasing chromosome loss and instability, with a critical step being the loss of 1p. We report a detailed cytogenetic investigation of chromosome aberrations in a series of 88 meningiomas using Giemsa banding and multicolor spectral karyotyping (SKY). Clonal chromosome aberrations were identified in 46 (52%) tumors by G banding. Thirty-five tumors showing complex chromosome aberrations not fully characterized by G banding were subsequently reanalyzed by SKY. The SKY technique refined the G-band findings in 18 (51%) of the tumors on which it was applied. The most common features of cytogenetic progression in the complex karyotypes were chromosome arm-specific losses relating to the formation of deletions and dicentric chromosomes involving 1p. Part or all of 1p was lost in 19 tumors. Five tumors showed evidence for the loss of 1p in a progressive step-wise series of telomeric fusions involving the formation of unstable intermediates. Five recurring dicentric chromosomes were identified, including dic (1;11)(p11;p11), dic(1;12)(p12 approximately p13;p11), dic(1;22)(p11;q12 approximately q13), dic(7;19)(p11;p11), and dic(19;22)(p11 approximately p13;q11 approximately q13). These findings provide evidence that telomeric fusions play a role in the formation of clonal deletions, dicentrics, and unbalanced translocations of 1p. The loss of 1p has possible diagnostic and prognostic implications in the management of meningioma.

Adult↗

Cytogenetic and fluorescence in situ hybridization characterization of clonal chromosomal aberrations and CCND1 amplification in esophageal carcinomas.

Cytogenetic analyses of four squamous cell carcinomas (SCC) of the esophagus showed complex numerical and structural abnormalities. Chromosomal bands or regions preferentially involved were 11q13, 8q10, 21q10, 3p10 approximately p11, 1p11 approximately q11, 5p11 approximately q11, and 14p11 approximately q11. For the first time, to our knowledge, recurrent aberrations were identified in esophageal SCC, including homogeneous staining region (hsr), isochromosomes i(3q) and i(21q), and ring chromosome. Losses of chromosomal material dominated over gains. Recurrent imbalances included under-representation of 4p13 approximately pter, 5q14 approximately qter, 9p22 approximately pter, 10p, 11p13 approximately pter, 12p13 approximately pter, 17p10 approximately pter, 18p11 approximately pter, 21p, and 22p, as well as over-representation of 1q25 approximately qter, 3q, 7q, and 8q. Interestingly, hsr at different chromosomal regions occurred in three of four cases. With the application of fluorescence in situ hybridization (FISH) and multicolor combined binary ratio labeling-FISH with specific DNA probes, it could be shown that in two cases the hsr was derived from chromosome 11 material and that the amplicon included CCND1. Our results, together with previous molecular genetic findings, indicate that CCND1might be a prime target in 11q13 amplification, and that amplification of this gene might be crucial in the tumorigenesis of esophageal SCC. These observed chromosomal aberrations and imbalances thus provide important information for further molecular genetic investigation of esophageal SCC.

Adult↗

Duplication of 2q31-qter as a sole aberration in a case of non-Hodgkin's lymphoma.

We report a case of peripheral T-cell lymphoma that was initially found to have the aberrant karyotype 47,XX,t(2;13)(q22;q22),+19. At relapse 2 years later, a malignant clone with the karyotype 46,XX,der(22)t(2;22)(q31;q13) was identified. This rearrangement leads to a duplication of the distal part of the long arm of chromosome 2. We used chromosome-specific painting libraries and multicolor fluorescence in situ hybridization, as a complement to banding analysis, to resolve the karyotype.

Chromosome Aberrations↗

Analysis of sperm chromosome complements before, during, and after chemotherapy.

Sperm chromosomal abnormalities were assessed in testicular cancer patients before, during, and after BEP (bleomycin, etoposide, cisplatin) chemotherapy (CT). Multicolor fluorescence in situ hybridization (FISH) analysis was employed to detect aneuploidy for chromosomes 1, 12, X, and Y, and diploidy. Sperm samples were cryopreserved and coded before analysis to facilitate "blind" analysis. Complete results at all time points was available for only one patient. A total of 60,400 sperm were analyzed: 20,004 before CT, 20,005 during CT, and 20,391 after CT. There was a significant increase in the frequency of 24,XY sperm during (0.33%) and post-CT (0.34%) compared to pre-CT (0.14%). This study suggests that there may be a significantly increased risk of chromosomal abnormalities in sperm of CT patients during and immediately post-CT, similar to that shown in animal models.

Adult↗

Trisomy 4 leading to duplication of a mutated KIT allele in acute myeloid leukemia with mast cell involvement.

A G-->T transversion at nucleotide 2467 of the c-KIT gene leading to Asp816-->Tyr (D816Y) substitution in the phosphotransferase domain has been previously identified in a patient with rapidly progressing AML-M2 and mast cell involvement; the patient's blasts had a 47,XY, +4,t(8;21)(q22;q22) karyotype. Herein we confirm the simultaneous presence of both major chromosomal changes by multicolor fluorescence in situ hybridization (FISH) on interphase CD34+ mononuclear cells. By setting up culture leukemic blasts, spontaneous differentiation of adherent cells with mast-cell like features was proved by histochemical and immunoenzymatic analyses. Fluorescence in situ hybridization evidence of trisomy 4 confirmed the origin of differentiated cells from the leukemic blasts. Semiquantitative polymerase chain reaction (PCR) and phosphoimage densitometry of wild-type and mutated KIT alleles on bone marrow blasts made it possible to demonstrate that chromosome 4 trisomy led to a double dosage of the mutated KIT allele. This finding, and that of trisomy 7 and MET mutation in hereditary renal carcinoma represent the only cases of human tumors in which an increased number of chromosomes carrying an oncogene activated by point mutation have been detected.

Acute Disease↗

The M-DC8-positive leukocytes are a subpopulation of the CD14+ CD16+ monocytes.

Recently, a population of M-DC8-positive leukocytes has been described as a new subpopulation of human dendritic cells (DC). In view of the expression of the CD16 antigen on these cells, as well as the finding that DC can arise from blood monocytes, we hypothesized that the expression of M-DC8 is mainly associated with the CD14+ CD16+ phenotype of blood monocytes. Immunofluorescence analysis of whole blood showed that the percentage of M-DC8+ cells is about three times lower than the percentage of CD14+ CD16+ monocytes among all leukocytes (0.32% versus 1.10%). Further, in addition to the expression of CD16, these M-DC8+ cells were also positive for CD14 at low density. Multicolor flow cytometric analysis of whole blood revealed that more than one third of the CD14+ CD16+ monocyte population expressed the M-DC8 antigen (42.3%), and almost all M-DC8+ cells were CD14-CD16-double-positive (87.5%). Finally, the M-DC8 antigen was also expressed on alveolar macrophages from healthy individuals, i.e., cells that are phenotypically and functionally related to the CD14+ CD16+ monocytes. Taken together, the data presented here clearly demonstrate that the M-DC8+ leukocytes are a subpopulation of the CD14+ CD16+ monocytes and may represent DC

Antibodies, Monoclonal↗