Telomere-specific clones are a valuable resource for the characterization of chromosomal rearrangements. We previously reported a first-generation set of human telomere probes consisting of 34 genomic clones, which were a known distance from the end of the chromosome ( approximately 300 kb), and 7 clones corresponding to the most distal markers on the integrated genetic/physical map (1p, 5p, 6p, 9p, 12p, 15q, and 20q). Subsequently, this resource has been optimized and completed: the size of the genomic clones has been expanded to a target size of 100-200 kb, which is optimal for use in genome-scanning methodologies, and additional probes for the remaining seven telomeres have been identified. For each clone we give an associated mapped sequence-tagged site and provide distances from the telomere estimated using a combination of fiberFISH, interphase FISH, sequence analysis, and radiation-hybrid mapping. This updated set of telomeric clones is an invaluable resource for clinical diagnosis and represents an important contribution to genetic and physical mapping efforts aimed at telomeric regions.

SummaryA mouse immunoglobulin G1 monoclonal antibody (mAb), MRC OX-62 (OX-62), was raised against density gradient-enriched rat veiled (dendritic) cells obtained from lymph. In suspensions of lymphoid cells, the OX-62 mAb only labeled cells with the characteristics of veiled cells. The OX-62 mAb was used with a magnetic cell sorter to enrich or deplete veiled cells, and the enriched veiled cells were potent stimulators in the primary allogeneic mixed leukocyte reaction. Immunohistochemical staining of tissue sections showed that the OX-62 mAb did not label all classical dendritic cells and was not restricted to this cell type. In lymphoid tissues, the labeling correlated with dendritic cells, but in skin, major histocompatibility complex class II + cells were OX-62-, while another CD3 + cell with dendritic morphology was strongly OX-62 + . It seems that the OX-62 mAb may be restricted to dendritic cells and probably to T/$ T cells. The OX-62 mAb will be of use in delineating minor subsets of cells with dendritic morphdogy in various tissues. Sodium dodecyl sulfate-polyacrylamide gel dectrophoresis analysis of veiled ceil-enriched populations immunoprecipitated with the OX-62 mAb gave bands with the biochemical characteristics of an integrin. The OX-62 mAb recognized the c~-like subunit. Dendritic cells are classified as a heterogeneous group of cells with dendritic morphology found in lymphoid and nonlymphoid tissues, and as veiled cells in lymph (1). Dendritic cells originate from bone marrow but the lineage is unresolved (2). Attention focused on dendritic cells after the isolation of the spleen dendritic cell and the observation that these cells are the most potent accessory cells identified at inducing primary T cell responses in vitro (3). The immunoregnlatory role of dendritic ceils in vivo is implicated by their presence in the T-dependent areas of secondary lymphoid organs (4, 5). Identification of dendritic ceils is based on properties of the isolated spleen dendritic cell, which indude dendritic morphology (6), constitutive expression of MHC class II (7), low phagocytic ability in vitro (8), and potent accessory function in the primary allogeneic MLR (3). The need for mAbs that are specific for dendritic calls is evident (9), but few useful mAbs are available (10-17), and anti-MHC class II mAbs are of limited value. One major problem in generating dendritic cell mAbs is that it is difficult to obtain large numbers of dendritic cells for immunization and there are no call lines equivalent to normal dendritic cells (18)(19)(20). In this paper the production of a mouse IgG1 mAb (OX-62) useful for the purification of rat veiled ceils and recognizing an antigen with the biochemical properties of an integrin is described. Materials and MethodsAnimals. BALB/c (H-2 d) and DBA/2 (H-2 d) inbred mice were obtained from the Sir William Dunn School of Pathology (Oxford). F1 hybrids between these two strains were bred at the MRC Cellular Immunology Unit (Oxford). PVG (RT1 ~ and AO (R.T1 u) specific pathogen-free inb...

SlLlnlmal'yThe relative inefficiency of respiratory mucosal immune function during infancy is generally attributed to the immaturity of the neonatal T cell system. However, immune competence in the adult lung has recently been shown to be closely linked to the functional capacity of local networks of intraepithelial dendritic cells (DC). This study examines the density and distribution of these DC throughout the neonatal respiratory tract in rats, focusing particularly on microenvironmental regulation of their class II major histocompatibility complex (MHC) (Ia) expression. In animals housed under dust-controlled conditions, airway epithelial and alveolar Ia § DC detectable by immunostaining with the monoclonal antibody (mAb) Ox6 are usually not seen until day 2-3 after birth, and adult-equivalent staining patterns are not observed until after weaning. In contrast, the mAb Ox62 detects large numbers of DC in fetal, infant, and adult rat airway epithelium. Costaining of these Ox62 § DC with Ox6 is rare in the neonate and increases progressively throughout infancy, and by weaning Ia § DC comprised, on average, 65% of the overall intraepithelial DC population. In infant rats, Ia § DC are observed first at the base of the nasal turbinates, sites of maximum exposure to inhaled particulates, suggesting that their maturation is driven in part by inflammatory stimuli. Consistent with this suggestion, densitometric analysis ofla staining intensity of individual DC demonstrates that by 2-3 d after birth, Ia expression by nasal epithelial DC was comparable with that of Iahie h epidermal Langerhans cells in adjacent facial skin, at a time when expression by tracheal epithelial DC was 7-10-fold lower. Additionally, the rate of postnatal appearance of Iahie h DC in the airway epithelium was increased by administration of interferon % and decreased by exposure of infant rats to aerosolized steroid. These findings collectively suggest that Ia expression by neonatal respiratory tract DC is locally controlled and can be upregulated by mediators that are produced within the lung and airway epithelium in response to inhalation of proinflammatory stimuli. It was also noted that Ia/~ neonatal airway DC expressed adult equivalent levels of class I MHC, which suggests differences in capacity to prime for CD8+-dependent versus CD4 § immunity to inhaled pathogens, during the early postnatal period.