To investigate the role of type X collagen in skeletal development, we have generated type X collagen-null mice. Surprisingly, mice without type X collagen were viable and fertile and had no gross abnormalities in long bone growth or development. No differences were detected between the type X collagen-null mice and controls when growth plates of both newborn and 3-week old mice were examined by histology and by immunostaining for extracellular matrix components of bone including osteopontin, osteocalcin and type II collagen. Our results suggest that type X collagen is not required for long bone development. However, mice and humans with dominant acting type X collagen mutations have bone abnormalities, suggesting that only the presence of abnormal type X collagen can modify bone growth and development.

We have generated transgenic mice harboring a glycine-to-cysteine mutation in residue 85 of the triple helical d in of mouse type II collagen. The offspring of different founders displayed a phenotype of severe chondrodysplasia characterized by short limbs and trunk, cranio-facial deformities, and cleft palate. The affected pups died of acute respiratory distress caused by an inability to inflate lungs at birth. Staining of the skeleton showed a severe retardation of growth for practically all bones. Light microscopic examination indicated a decrease in cartilage matrix density, a severe disorganization of growth plate architecture, and the presence of streaks of fibrillar material in the cartilage matrix. Electron microscopic analysis showed a pronounced decrease in the number of typical thin cartilage collagen fibrils, distension of the rough endoplasmic reticulum of chondrocytes, and the presence of abnormally large banded collagen fibril bundles.The level of expression of the mutant type II procollagen a, chain transgene in cartilage tissues was approximately equal to that of the endogenous gene in two of the strains. We propose that the principal consequence ofthe mutation is a considerable reduction in density of the typical thin cartilage collagen fibrils and that this phenomenon causes the severe disorganization of the growth plate. We also postulate that the abnormal thick collagen fibrils are probably related to a defect in crosslinking between the collagen molecules. The cartilage anomalies displayed by these transgenic mice are remarkably similar to those of certain human chondrodysplasias. Fig. 1), 3 kb of 5' flanking sequences, and 7 kb of 3' flanking sequences was released from the cosmid vector by Not I digestion. DNA was microinjected into pronuclei of one-cell mouse embryos, obtained from C57BL/6 x DBA/2J F1 (hereafter called B6D2F1) females mated with B6D2F1 males, which were implanted into BALB/c x DBA1 (hereafter called CD1) pseudopregnant foster mothers (7). The transgenic founders were identified by Southern hybridization of Nco I-digested tail genomic DNA with an EcoRI-Pst I DNA fragment from intron 6 to intron 8 (see Fig. 1C). This probe hybridizes to 540-and 628-base-pair (bp)

Sarcoidosis is a granulomatous inflammatory disease, diagnosed through tissue biopsy of involved organs in the absence of other causes such as tuberculosis (TB). No specific serologic test is available to diagnose and differentiate sarcoidosis from TB. Using a high throughput method, we developed a T7 phage display cDNA library derived from mRNA isolated from bronchoalveolar lavage (BAL) cells and leukocytes of sarcoidosis patients. This complex cDNA library was biopanned to obtain 1152 potential sarcoidosis antigens and a microarray was constructed to immunoscreen two different sets of sera from healthy controls and sarcoidosis. Meta-analysis identified 259 discriminating sarcoidosis antigens, and multivariate analysis identified 32 antigens with a sensitivity of 89% and a specificity of 83% to classify sarcoidosis from healthy controls. Additionally, interrogating the same microarray platform with sera from subjects with TB, we identified 50 clones that distinguish between TB, sarcoidosis and healthy controls. The top 10 sarcoidosis and TB specific clones were sequenced and homologies were searched in the public database revealing unique epitopes and mimotopes in each group. Here, we show for the first time that immunoscreenings of a library derived from sarcoidosis tissue differentiates between sarcoidosis and tuberculosis antigens. These novel biomarkers can improve diagnosis of sarcoidosis and TB, and may aid to develop or evaluate a TB vaccine.

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