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D N Hart

Publications and source records attributed to D N Hart.

At least 37 records · Page 2Linked to original sources
PubMed1999

Expression of the RelB transcription factor correlates with the activation of human dendritic cells.

The RelB gene product is a member of the nuclear factor (NF)-kappaB family of transcription factors. It has been identified recently within mouse antigen-presenting cells and human monocyte-derived dendritic cells (DC). Disruption of the mouse RelB gene is accompanied, amongst other phenotypes, by abnormalities in the antigen-presenting cell lineages. In order to define RelB expression during human DC differentiation, we have analysed RelB mRNA by reverse transcriptase-polymerase chain reaction and RelB protein by intracellular staining in CD34+ precursors and different types of DC preparations. RelB mRNA was not detected in CD34+ precursor populations. Fresh blood DC (lineage-human leucocyte antigen-DR+ (lin-HLA-DR+)) lacked RelB mRNA and cytoplasmic RelB protein but a period of in vitro culture induced RelB expression in blood DC. Purified Langerhans' cells (LC) (CD1a+ HLA-DR+) failed to express RelB mRNA. Immunocytochemical staining identified RelB protein in human skin epithelium. RelB protein was expressed in a very few CD1a+, CD83+ or CMRF-44+ dermal DC but was not present in CD1a+ LC. Tonsil DC (lin-HLA-DR+ CMRF-44+) were positive for RelB mRNA and RelB protein. Intestinal DC (HLA-DR+) also lacked immunoreactive RelB protein. The majority of interdigitating CD83+, CMRF-44+, CMRF-56+ or p55+ DC located in paracortical T-lymphocyte areas of lymph node and tonsil contained RelB protein. The expression of RelB mRNA and RelB protein correlates with the activated phase of blood DC and the postmigration cell (activated) stage of tissue DC development.

Antigens, CD34↗
PubMed1999

Induction of dendritic cell costimulator molecule expression is suppressed by T cells in the absence of antigen-specific signalling: role of cluster formation, CD40 and HLA-class II for dendritic cell activation.

Full activation of T lymphocytes by dendritic cells (DC) during antigen presentation is known to require the interaction of several inducible receptor-ligand pairs. We have postulated that the reciprocal activation of DC by T lymphocytes is also important. Potential signalling molecules that might increase the stimulatory capacity of DC during antigen presentation to T lymphocytes were tested using an in vitro model. Fresh human blood DC were cocultured with CD4+ and CD8+ allogeneic or with autologous T lymphocytes plus Staphylococcus superantigen A (SEA). Surprisingly, costimulator expression on DC cocultured with T lymphocytes was reduced in comparison to DC cultured alone. However, the minority (10-30%) of DC clustering with T lymphocytes showed antigen-specific up-regulation of the CD40, CD80 and CD86 costimulator molecules, whereas the non-clustered DC (70-90%) had less up-regulation than control DC cultured alone and did not respond to antigen-specific triggering. Monoclonal antibodies (mAb) to CD40 ligand (CD40L) and human leucocyte antigen (HLA)-DR, but not lymphocyte function-associated antigen-1 (LFA-1), LFA-3 or HLA-class I, significantly inhibited the T-lymphocyte induction of DC costimulator expression. Since HLA-class II, but not HLA-class I mAb, inhibited allogeneic T-lymphocyte-mediated activation of DC, CD4 T lymphocytes appear to be the main subset activating DC in the mixed lymphocyte reaction. Cross-linking of CD40, but not HLA-class II, up-regulated DC or B-cell costimulator expression. Although direct class II signalling does not appear to play a role in DC activation, antigen-specific T-cell recognition contributes via other mechanisms to regulate DC activation.

Antibodies, Monoclonal↗
PubMed1999

Dendritic cell immunotherapy for cancer: application to low-grade lymphoma and multiple myeloma.

The confirmation that most cancers express one or more molecular changes, which may act as tumour-associated antigens (TAA), combined with the knowledge that T lymphocytes recognize even single amino acid differences in MHC presented peptides has stimulated renewed clinical interest in immunotherapeutic strategies. Dendritic cells (DC) are now recognized as specialist antigen-presenting cells, which initiate, direct and regulate immune responses. Recent data suggest that DC are not recruited into, or activated by, cancers and that other abnormalities in DC function are associated with malignancy, including multiple myeloma. This provides a rationale for designing immunotherapeutic strategies, which exploit DC as nature's adjuvant either in vivo or in vitro. Low-grade lymphoma and multiple myeloma are slowly progressive malignancies, which generally express a unique immunoglobulin idiotype as a potential TAA. Data from animal models and clinical studies suggest that DC-based immunotherapy strategies, applied when the patient has minimal residual disease, may improve the long-term prognosis in these diseases.

Animals↗
PubMed1999

CD1a dendritic cells predominate in transitional cell carcinoma of bladder and kidney but are minimally activated.

PURPOSE: In this study, we employed similar techniques to detail dendritic cell subsets within bladder transitional cell carcinoma and kidney transitional cell carcinoma. MATERIALS AND METHODS: To identify both the CD1a+ and CD1a- antigen-expressing dendritic cell populations we employed a double labeling technique to identify non-lineage-expressing leukocytes similar to that employed to isolate blood dendritic cells. RESULTS: Dendritic cells were found in significant numbers within both bladder and kidney derived transitional cell carcinoma. Almost all the dendritic cells among the tumor cells belonged to the CD1a+ subset of epithelial dendritic cells. Similar numbers of dendritic cells were observed in the lamina propria adjacent to the tumor. These dendritic cells belonged predominantly to the CD1a- subset. These differences appear to reflect the different dendritic cell phenotypes reported for the epidermis and dermis. CONCLUSIONS: The number of dendritic cells increased as the grade of the tumor increased, reflecting an overall higher leukocyte density in higher grade tumors. However, a possible trend for less dendritic cell activation in higher grade cancers was noted, raising the intriguing possibility that this might be a relevant prognostic factor, to be confirmed in a larger study.

Antigens, CD1↗
PubMed1999

Presentation of tumor antigens.

Dendritic cells, with their extraordinary capacity for initiating primary and secondary T-lymphocyte responses, may be pivotal in the development of immunotherapeutic strategies for multiple myeloma. Although host lymphocytes are able to recognize tumor-associated antigens (TAAs), many tumors are able to avoid dendritic cell-mediated immune surveillance. One reason may be that the tumor environment inhibits the maturation and activation of dendritic cells. A recently developed strategy to use dendritic cells in immunotherapy involves removing them from the tumor, pulsing them in vitro with antigen, and reinfusing them into the patient to generate responding T cells in vivo. Methods for reliably obtaining dendritic cells for therapeutic use are currently being investigated. Among other efforts to induce T-cell-mediated immunity against cancer, the presentation of tumor antigens by the tumor cells themselves is being investigated. Issues to be resolved include defects of antigen presentation by tumor cells and whether all cells present the same set of peptides. Moreover, as long as all the tumor antigens have not been identified, the tumor cell itself remains the primary source of unknown antigens and, therefore, is a worthwhile subject for study. Phase I trials of immunotherapy using adenovirus-infected autologous plasma cells have recently been undertaken. The adenoviral vectors carry genes with therapeutic potential, including interleukin-2 (IL-2), interleukin-12, and B7-1. Initial results showed that the vector can be readily detected in tumor cells at 13 days postinjection, and IL-2 expression was evident at 7 days. The chief side effect reported was inflammation.

Antigen Presentation↗
PubMed1998

Optimisation of the conditions for generating human DC initiated antigen specific T lymphocyte lines in vitro.

Naive T lymphocytes specific for a given primary antigen occur in low frequencies and require the relevant antigen to be presented by specialist antigen presenting cells (APC), i.e., dendritic cells (DC). For these reasons, the in vitro induction of primary T lymphocyte responses remains a significant technical challenge. We have attempted to improve current strategies for generating in vitro responses by optimising (i) isolation and concomitant activation of DC from peripheral blood, (ii) uptake, processing and presentation of antigen by DC and (iii) antigen driven T lymphocyte proliferation. We established that RPMI 1640 media supplemented with 10% autologous serum resulted in the best yield of CMRF-44+, CD14-, CD19- DC after enrichment over a Nycodenz gradient. Optimal presentation of whole protein and peptide antigen was achieved by addition after the purification of the APC, i.e., at the start of the T lymphocyte proliferation assay. RPMI 1640 supplemented with 10% autologous serum or plasma supported the best antigen driven specific T lymphocyte responses. Using these optimised conditions, we compared the efficacy of PBMC and purified blood DC for priming T lymphocyte responses to the chronic myeloid leukaemia (CML) specific bcr-abl (b3a2) peptide. Peptide specific T lymphocyte responses were generated with both purified DC and whole PBMC, suggesting that T lymphocyte precursor frequency was the limiting factor in these experiments. These results will aid in the generation of human T lymphocyte lines to primary antigens, for in vitro and therapeutic applications.

Animals↗
PubMed1998

Type I IFNs enhance the terminal differentiation of dendritic cells.

This study identifies type I IFNs as activating cytokines in a serum-free system in which human dendritic cells (DC) were generated from CD34+ progenitor cells. After 14 days of culture in GM-CSF, TNF-alpha, and IL-4, CD34+ progenitors gave rise to a population of large, immature DC expressing CD1a and CD11b but lacking CD14, CD80, CD83, CD86, and CMRF44. During the next 2 wk, this population spontaneously matured into nonadherent, CD1a(low/-), CD11b(low/-), CD14-, CD80+, CD83+, CD86+, CMRF44+ DC with high allostimulatory activity in the MLR. To examine which factors influenced this maturation, 25 different cytokines or factors were added to the immature DC culture. Only type I IFNs (alpha or beta) accelerated this maturation in a dose-dependent manner, so that after only 3 days the majority of large cells acquired the morphology, phenotype, and function characteristics of mature DC. Furthermore, supernatants from cultures containing spontaneously maturing DC revealed low levels of endogenous IFN production. Because of the similarity of the activation of DC in our culture system with the phenotypic and functional changes observed during Langerhans cells activation and migration in vivo, we investigated the effect of IFN-alpha on human Langerhans cell migration. IFN-alpha also activated the migration of human split skin-derived DC, demonstrating that this effect was not limited to DC derived in vitro from hemopoietic progenitor cells. DC activation by type I IFNs represents a novel mechanism of immunomodulation by these cytokines, which could be important during antiviral responses and autoimmune reactions.

Adjuvants, Immunologic↗
PubMed1998

cDNA cloning of human DEC-205, a putative antigen-uptake receptor on dendritic cells.

Dendritic cells (DC) are specialist antigen presenting cells which capture antigens in the periphery, migrate centrally, and present the processed antigens in the context of major histocompatibility complex and appropriate co-stimulatory molecules to T lymphocytes for the initiation of an immune response. DEC-205 has been identified as a putative antigen-uptake receptor, which is expressed abundantly on mouse DC. The recently cloned mouse DEC-205 cDNA predicts a molecular structure which has a marked similarity to the macrophage mannose receptor. Using reverse transcriptase-polymerase chain reaction (RT-PCR) and cDNA library screening, we obtained the full coding region of human DEC-205 cDNA from the Hodgkin's disease-derived L428 cell line. The predicted protein structure is a type I transmembrane protein of 1722 amino acids consisting of a signal peptide, cysteine-rich domain, fibronectin type II domain, ten carbohydrate recognition-like domains, transmembrane domain, and a cytoplasmic tail. Human DEC-205 is 77% identical to the mouse protein with completely conserved cysteines. The DEC-205 gene (LY75) was mapped to chromosome band 2q24 by somatic cell hybrid panel analysis and fluorescent in situ hybridization. Northern blot analysis detected 7.8 and 9.5 kilobase DEC-205 transcripts in myeloid, B lymphoid, and Hodgkin's disease-derived cell lines. RT-PCR analysis indicated that immature blood DC contain a barely detectable amount of DEC-205 transcripts but these were markedly increased upon differentiation/activation.

Amino Acid Sequence↗
PubMed1998

Human dendritic cells express functional interleukin-7.

Interleukin-7 (IL-7) supports the proliferation of mature T lymphocytes, however, the cellular source of IL-7 for T lymphocyte activation has not been well established. We therefore investigated whether human peripheral blood dendritic cells (DC) produce IL-7 as a contribution towards T lymphocyte activation. Human CMRF-44+/CD14-/CD19- low density DC, purified after overnight tissue culture, contained IL-7 transcripts, detected by direct cell reverse transcription-polymerase chain reaction. Intracytoplasmic staining confirmed IL-7 protein in at least a subpopulation of cultured low density DC. In contrast, resting/immature DC, isolated directly by immunodepletion of lineage marker positive cells, contained no IL-7 mRNA. Thus, the expression of IL-7 by DC follows the pattern described previously for CD80, CD86 and CD40. However, tissue culture of purified resting/immature DC, in contrast to CD80, CD86 and CD40, failed to induce IL-7 transcripts. The functional importance of DC IL-7 expression was demonstrated in an allogeneic mixed leukocyte reaction (MLR). Neutralising mAb to IL-7 significantly inhibited T lymphocyte proliferation when low DC numbers were used, but at higher stimulator numbers, anti-IL-7 mAb failed to inhibit an allogeneic MLR. This suggests, that when DC are in excess, other co-stimulatory pathways can compensate for the lack of IL-7. Addition of IL-7 to a MLR caused a significant increase in the proliferative response stimulated by monocytes and B lymphocytes but not by DC. These data support the concept of an initial phase of antigen uptake by DC followed by the optimisation of DC co-stimulatory potential. The co-stimulatory repertoire expressed, including IL-7, may be regulated by exogenous stimuli, thereby ensuring DC flexibility in mounting a response appropriate to the environmental changes.

Cells, Cultured↗
PubMed1998

Invasive aspergillosis in severely neutropenic patients over 18 years: impact of intranasal amphotericin B and HEPA filtration.

The impact of intranasal amphotericin B and high-efficiency particulate air (HEPA) filtration on the incidence of invasive aspergillosis was reviewed in patients from 1977 to 1994 undergoing intensive chemotherapy. Overall, the incidence of proven invasive aspergillosis was reduced from 24.4% (1977-1984) to 7.1% (1985-1991) (P < 0.001) following the introduction of intranasal prophylaxis, but when probable cases of aspergillosis were included and lymphoma cases excluded, there was no change in incidence. Following the introduction of HEPA filtration, patient exposure to aspergillus spores as measured by air sampling was markedly reduced and there were no new cases of invasive aspergillosis. HEPA filtration proved effective in reducing invasive aspergillosis and has allowed increasingly aggressive treatment regimens to be introduced.

Administration, Intranasal↗
PubMed1998

Molecular cloning and functional analysis of the CD33 promoter.

CD33 is a leucocyte differentiation antigen restricted to myeloid cells in blood and bone marrow. Two mRNA transcripts encoding CD33 are observed in leukaemic cell lines. The smaller transcript of 1.5 kb is comparable in size to the isolated CD33 cDNA but the origin of the larger 1.8 kb transcript is unknown. To study the regulation of human CD33 expression, a 5' genomic clone from the CD33 gene was isolated and studied for promoter activity. The clone, although lacking a TATAA box, exhibits other sequences characteristic of a promoter. Two transcriptional start sites were identified, 414 and 527 nucleotides 5' of the ATG initiation codon, suggesting that these sites are used to generate the 1.8 kb transcript observed in CD33+ cell lines. The CD33 genomic sequence directed high expression of a luciferase reporter gene in myeloid cell lines. Using deletion mutants of the promoter sequence, maximal expression was localized to the first 220 bp 5' of the ATG initiation codon. Site-directed mutagenesis of an Sp-1 and PU.1 binding site within this region showed that the PU.1, but not Sp-1, was critical for CD33 expression in myeloid lines. Given the restricted expression of CD33 on haemopoietic cells, the identification of the CD33 promoter may be useful for the study of transcription factors that regulate gene expression during early myeloid differentiation.

Antigens, CD↗
PubMed1998

A long-lasting interferon-gamma response is induced to a single inoculation of antigen-pulsed dendritic cells.

Vaccines against infectious organisms must produce not only long-lasting immunity but also the appropriate immune response to clear the infection. Obligate intracellular parasites, such as mycobacteria, require a predominantly cell-mediated immune response rather than antibody. Presentation of antigen by dendritic cells (DC) has been associated with the development of strong cell-mediated responses generating the production of interferon-gamma (IFN-gamma). This cytokine has an essential role in the elimination of mycobacteria. Therefore, we investigated both the duration and the nature of the immune response after priming with DC pulsed with mycobacterial antigen and compared this with priming using a conventional adjuvant. We used two strains of mice: C57BL/6, which inherently produces a T-helper 1 (Th1)-type response to mycobacterial antigen, and BALB/c, which does not. DC-enriched cell suspensions, purified DC or cultured bone marrow cells resembling DC (BMAPC) were prepared, pulsed overnight with PPD and injected intravenously (i.v.) into naive mice. Six and 12 weeks later, splenic T lymphocytes from these mice were challenged in vitro with antigen and their proliferative response and cytokine production was determined. Significant antigen-specific proliferation was observed in all assays on rechallenge with antigen in vitro 6 and 12 weeks after the initial priming with DC. IFN-gamma was detected in both strains but was only antigen specific in the C57BL/6 strain. Purified protein derivative (PPD)-pulsed BMAPC generated similar responses 6 weeks after priming. Thus, long-term T-lymphocyte responses and the production of IFN-gamma can be generated using a single inoculation of PPD-pulsed DC.

Animals↗
PubMed1998

Blockade of B7-2, not B7-1, inhibits purified protein derivative-primed T-lymphocyte responses but fails to influence the proportion of Th1 versus Th2 subsets.

The ability to select for a cell-mediated response rather than antibody production following infection with intracellular mycobacteria, would be an advantage in preventing the occurrence of disease. Recent work suggests that the two members of the B7 family of costimulatory molecules, B7-1 and B7-2, may differentially influence the nature of primary immune responses but little is known of their role in this capacity in secondary responses. We have used an in vitro model to investigate whether blocking B7-1 and B7-2 affects changes in the cytokine profiles of Th lymphocytes previously primed to purified protein derivative (PPD) from Mycobacterium bovis. In C57BL/6 and BALB/c mice we found that the proliferative responses of a component of recently activated T lymphocytes, and those returning to the resting state, were inhibited by B7-2 blockade. B7-1 blockade had no distinguishable effect. However, in cultures containing anti-B7-2 antibody, the production of both interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), indicative of cell-mediated and antibody responses, respectively, were reduced. This suggests that intervention in a recall response to mycobacterial antigen by blocking B7-1 or B7-2 molecules, is unlikely to alter the nature of the immune response.

Animals↗
PubMed1998

Dermal dendritic cells associated with T lymphocytes in normal human skin display an activated phenotype.

The CMRF-44 and CD83 (HB15) antigens are associated with functional maturation and activation of blood dendritic cells (DC). We describe the expression of these antigens on freshly isolated epidermal Langerhans cells and dermal DC as well as the distribution of CD83+/ CMRF-44++-activated DC within sections of normal human skin. Fresh Langerhans cells were prepared by standard techniques and large numbers of enriched (25%-55%), viable dermal DC were obtained using an improved collagenase treatment protocol with density gradient enrichment. Freshly isolated Langerhans cells and dermal DC had similar costimulator and activation antigen expression, and both stimulated moderate levels of allogeneic T lymphocyte proliferation as determined in the 7 d mixed leukocyte reaction. In situ labeling of DC within skin sections revealed a population of CD83 and CMRF-44 positive dermal cells of which most (approximately 75%) were in intimate contact with CD3+ T lymphocytes, especially in the adnexal regions. In contrast, only 25%-30% of the more numerous CD1a++ dermal DC population were directly apposed to T lymphocytes. The CMRF-44++ dermal DC population stimulated an allogeneic mixed leukocyte reaction, confirming their identity as DC. These data, plus comparative data obtained for migratory dermal DC, suggest that only a small proportion of dermal DC have been triggered to a more advanced state of differentiation or activation. The striking association of the activated dermal DC population with T lymphocytes suggests that communication between these two cell types in situ may occur early in the immune response to cutaneous antigen.

Antigen-Presenting Cells↗
PubMed1998

The CMRF-35 mAb recognizes a second leukocyte membrane molecule with a domain similar to the poly Ig receptor.

The CMRF-35 mAb recognizes an antigen found on most leukocytes including monocytes, neutrophils, macrophages, dendritic cells, and subpopulations of lymphocytes and bone marrow cells. A cDNA expressing the CMRF-35 epitope was isolated by expression cloning and this predicts for a type I cell surface glycoprotein belonging to the Ig superfamily. Here we demonstrate that the CMRF-35 mAb recognizes an epitope more widely distributed on hemopoietic cells and cell lines than suggested by expression analysis of the CMRF-35 mRNA. Furthermore, we have isolated a novel cDNA (CMRF-35-H9) that encodes a protein product also recognized by the CMRF-35 mAb. This cDNA product is a type I cell surface glycoprotein with a single Ig V-like domain. Although the sequences of the extracellular V-like domains of the two molecules are very similar, there is little similarity between the remainder of their sequences. The two transcripts are expressed independently of each other, and their presence accounts for the discrepancy between CMRF-35 mAb binding and mRNA analysis. The cytoplasmic tail of CMRF-35-H9 contains motifs similar to the inhibitory motifs found in some leukocyte surface receptors. Their expression in hemopoietic cells suggests that these two molecules may play distinct but related roles in the regulation of leukocyte function.

Amino Acid Sequence↗
PubMed1998

Minimal recruitment and activation of dendritic cells within renal cell carcinoma.

Dendritic cells (DCs) are predicted to participate in natural tumor immunity by migrating into tumors, where they acquire antigen, undergo activation, and migrate to lymph nodes to initiate a T-lymphocyte response against tumor-associated antigens. The presence of DCs using defined lineage markers and their function in human tumors has not been assessed previously. The monoclonal antibodies against CMRF-44 and CD83, which are differentiation/activation antigens on DCs, were used in immunohistological and flow cytometry studies to analyze the DC subtypes infiltrating 14 cases of human renal cell carcinoma (RCC). The functional immunocompetence of the DCs isolated from RCC was assessed by testing their ability to stimulate an allogeneic mixed leukocyte reaction. The majority of leukocytes present within the RCC were macrophages (62% +/- 14.7) or T lymphocytes (19% +/- 9.5), with CD45+ HLA-DR+ lineage-negative putative DCs accounting for less than 10% of the leukocytes present. Of these, a subset, comprising less than 1% of total leukocytes, had an activated CMRF-44+ or CD83+ DC phenotype. Activated CMRF-44+ and CD83+ DCs were more evident outside the tumor in association with T-lymphocyte clusters. The number of CMRF-44+ DCs correlated closely with the number of S-100-positive DCs. Isolation of DCs from eight RCCs was achieved, and flow cytometry studies confirmed the small proportion of activated CMRF-44+ DCs. The CMRF-44+ DCs stimulated an allogeneic mixed leukocyte reaction, but the CMRF-44- DCs (normal tissue DC precursors and other cells) failed to do so. These results suggest that RCCs recruit few DCs into the tumor substance, and the tumor environment fails to initiate the expected protective activation of DCs. These two mechanisms, amongst others, may contribute to tumor escape from immunosurveillance. In vitro loading of DCs with tumor-associated antigens may be a useful therapeutic maneuver.

Antigens, CD↗
PubMed1998

Generation of CMRF-44+ monocyte-derived dendritic cells: insights into phenotype and function.

The CMRF-44 monoclonal antibody (MoAb) recognizes an intermediate stage of blood dendritic cell (DC) differentiation as well as mature CD83+ blood DC. Here we describe the use of the CMRF-44 MoAb to monitor the in vitro development of DC-like cells from peripheral blood mononuclear cells. Neither granulocyte-macrophage colony-stimulating factor (GM-CSF) nor GM-CSF plus tumor necrosis factor-alpha (TNF-alpha) supported the development of CMRF-44+ cells. However, GM-CSF plus interleukin (IL)-4 generated a substantial number of CMRF-44+ cells among the heterogeneous CD14- myeloid cell population, produced after 7 or 10 days of culture. The addition of TNF-alpha to GM-CSF+IL-4 on the fifth day of culture enhanced the generation of CMRF-44+ cells from days 7 to 14. A concentration of 50 U/mL of IL-4 was sufficient to allow the development of CMRF-44+ cells. The presence of GM-CSF was essential, but a wide range of concentrations (50-800 U/mL) was effective for supporting IL-4-induced generation of CMRF-44+ cells. TNF-alpha at concentrations of 20 or 50 ng/mL induced a maximal increase in the number of CMRF-44+ cells. The CMRF-44+ DCs generated in the presence of GM-CSF+IL-4 were large, irregularly shaped cells with variable CD1a expression and have CD83 transcripts but no CD83 surface expression. Additional TNF-alpha treatment induced prominent dendritic processes and surface expression of CD83 on CMRF-44+ DCs. The CMRF-44+ DCs generated in GM-CSF+IL-4 showed higher allostimulatory activity than CMRF-44 cells but were less efficient at processing and presenting soluble antigen to T-lymphocyte lines. TNF-alpha treatment reduced antigen uptake but increased the allostimulatory activity of CMRF-44+ DCs. CMRF-44+ DC differentiation from blood CD14+ monocytes was not radiosensitive and thus does not involve cell division. We conclude that the MoAb CMRF-44 identifies both intermediate and fully mature stages of monocyte-DC differentiation and may be a useful marker in establishing the optimal timing for antigen loading of in vitro-generated monocyte-derived DCs.

Antibodies, Monoclonal↗