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Individuals with Down syndrome have an increased risk of leukaemia, but reliable estimates of the age-specific risk of leukaemia are lacking and very little is known about the risk of solid tumours. We identified 2814 individuals with Down syndrome from the Danish Cytogenetic Register, and linked the data to the Danish Cancer Registry. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated on the basis of age- and sex-specific cancer rates in the general population. Sixty cases of cancer were observed, with 49.8 expected (SIR = 1.20; CI: 0.92-1.55). Leukaemia constituted 60% of the malignancies overall and 97% of the malignancies in children. The SIR for leukaemia varied considerably with age, being 56 (CI: 38-81) at age 0-4 years and 10 (CI: 4-20) at 5-29 years. No cases of leukaemia were observed after age 29. The cumulative risk of leukaemia by the age of 5 years was 2.1% and that by 30 years was 2.7%. Only 24 solid tumours were observed with 47.8 expected (SIR = 0.50; CI: 0.32-0.75). No cases of breast cancer were observed, with 7.3 expected (p = 0.0007). Increased risks of testicular cancer, ovarian cancer, and retinoblastoma were observed but were not statistically significant. The occurrence of cancer in Down syndrome is unique with a high risk of leukaemia in children and a decreased risk of solid tumours in all age groups. The distinctive pattern of malignancies may provide clues in the search for leukaemogenic genes and tumour suppressor genes on chromosome 21.

Tetranectin, a plasminogen-binding protein belonging to the family of C-type lectins, was expressed in E. coli and converted to its native form by in vitro refolding and proteolytic processing. Recombinant tetranectin-as well as natural tetranectin from human plasma-was shown by chemical cross-linking analysis and SDS-PAGE to be a homo-trimer in solution as are other known members of the collectin family of C-type lectins. Biochemical evidence is presented showing that an N-terminal domain encoded within exons 1 and 2 of the tetranectin gene is necessary and sufficient to govern subunit trimerization.

Tetranectin is a tetrameric human plasma protein that binds to plasminogen kringle 4. Its amino acid sequence is homologous with the C-terminal parts of asialoglycoprotein receptors and proteoglycan core proteins. In the present study, we have demonstrated that the human embryonal fibroblast cell line WI-38 produce a tetranectin-related molecule, which might, by several criteria, be similar to tetranectin from plasma. These criteria include immunoblotting analysis of conditioned cell medium revealing a protein band with Mr 17,000, indistinguishable from the Mr of plasma tetranectin. A preparation obtained by purification of conditioned medium by affinity chromatography on an anti-(plasma tetranectin) IgG column also contained the Mr 17,000 protein. This protein (partly purified from the conditioned medium) was shown by crossed immunoelectrophoresis to bind to heparin, CaCl2 and plasminogen kringle 4, as previously described for tetranectin in plasma. Importantly, this tetranectin-related protein is not only present in conditioned culture medium, but the Mr 17,000 protein reacting with anti-(plasma tetranectin) IgG was also present in the extracellular material, remaining after removal of WI-38 cells from the culture dishes, as demonstrated by immunoblotting analysis and immunocytochemical staining. We conclude that WI-38 cells produce a tetranectin-related protein and secrete it into the extracellular matrix.

Tetranectin, a recently described human protein widely distributed in the body and with possible importance for cell growth and differentiation, has previously been observed to be decreased in patients with solid malignant tumors. In patients with multiple myeloma, either untreated or previously treated, serum levels were found to be significantly reduced. A negligible interindividual variation was observed. Levels of serum tetranectin were not correlated with serum albumin, hemoglobin, or M-component. Low levels of tetranectin may be related to the growth and spread of malignant cells or reflect a general catabolic state of chronic disease.

Purification of alpha 2-plasmin inhibitor (alpha 2PI) from human plasma by affinity chromatography on plasminogen-Sepharose resulted in copurification of a contaminating protein with Mr 17,000 as judged by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. This contaminating protein could not be removed from the purified alpha 2-PI preparation by several types of gel chromatography applied. The use of the kringle 1-3 part of plasminogen, K(1 + 2 + 3), bound to Sepharose for affinity chromatography, instead of plasminogen-Sepharose, resulted in an alpha 2PI preparation without this contaminant. The contaminating protein was found to interact specifically with the kringle 4 part of plasminogen (K4) and not with K(1 + 2 + 3) or miniplasminogen. The K4-binding protein was purified by ammonium sulphate precipitation, affinity chromatography on K4-Sepharose, ion-exchange chromatography and gel filtration on AcA 34. The relative molecular mass of the protein (Mr 68 000) was estimated by gel filtration. This suggests a tetrameric protein composed of four subunits (Mr 17,000), that are dissociated by 1% sodium dodecyl sulphate. Dissociation into subunits was also demonstrated by gel filtration in the presence of 6 M guanidine hydrochloride. A specific antibody was raised in rabbits against the purified protein and this antibody was shown not to react with any known fibrinolytic components. The pI of the K4-binding protein was found to be 5.8. The first three N-terminal amino acids were determined to be Glu-Pro-Pro. The concentration of the protein in plasma was estimated to be 0.20 +/- 0.03 microM (15 +/- 2 mg/l). The electrophoretic mobility of the K4-binding protein was shown by crossed immunoelectrophoresis to be influenced by the presence of Ca2+, EDTA and heparin. The protein was found to enhance plasminogen activation catalyzed by tissue-type plasminogen activator (t-PA) in the presence of poly(D-lysine). The protein appeared to be a novel plasma protein tentatively called 'tetranectin'.

The concentration of fibronectin in rheumatoid synovial fluid was found to be 2-3 times higher than in the corresponding plasma. Normal plasma revealed a homogeneous precipitate by cross- immunoelectrophoresis using antifibronectin, while rheumatoid plasma and rheumatoid synovial fluid exhibited a heterogeneous precipitate. The heterogeneous precipitate in rheumatoid plasma was found to be a complex between fibronectin and fibrinogen as evidenced by cross-immunoelectrophoresis. Synovial fluid fibronectin demonstrated a lower molecular weight by gelfiltration on Sepharose CL6B than did normal plasma fibronectin. We suggest that the presence of degraded fibronectin in rheumatoid synovial fluid may be the result of either the degradation of fibrin-fibronectin complexes or the destruction of matrix fibronectin from the synovial tissue.

The progressive inhibition of plasmin by pancreatic trypsin inhibitor and by alpha 2-plasmin inhibitor in the presence of D-valyl-L-leucyl-L-lysine 4-nitroanilide was investigated. The kinetics with plasmin were compared with those with miniplasmin. The kinetic properties of two functionally different forms of alpha 2-plasmin inhibitor described by Clemmensen [(1979) in The Physiological Inhibitors of Coagulation and Fibrinolysis (Collen. D., Wiman, B & Verstraete, M., eds.), pp 131-136, Elsevier, Amsterdam] were characterized. The two forms differ in their plasminogen-binding capability, and this difference can account for a difference in secondary site interaction suggested from the kinetics. The binding of inhibitor to miniplasmin is a simple pseudo-first-order reaction with both pancreatic trypsin inhibitor and the two alpha 2-plasmin inhibitor forms. Such simple kinetics are also observed for the reaction between plasmin and the non-plasminogen-binding form of alpha 2-plasmin inhibitor. More complicated kinetics are obtained for the reaction between plasmin and the alpha 2-plasmin inhibitor form that binds to plasminogen. With both forms of the alpha 2-plasmin inhibitor, a complex stable to acetic acid/urea and gel electrophoresis is present and fully developed 15 s after initiation of the reaction with plasmin.

A previously fit 66-years-old male primarily presented symptoms compatible with Henock-Schönlein's purpura, from which he seemingly recovered. Shortly hereafter he relapsed with an IgM lambda essential monoclonal cryoglobulinemia type I, presenting a systemic, necrotizing vasculitis, with low titer of circulating immune complexes and complement consumption. Glucocorticoid treatment and plasmapheresis did not prevent an ultimately lethal course. An indirect immunoperoxidase technique showed that the cryo-IgM bound to the interstitial connective tissue corresponding to the localization of collagen type I. In addition it bound to affinity purified human procollagen type I. These results indicate, that the IgM lambda of the proband was an autoantibody with collagen type I specificity.

Inflammatory exudates from 10 patients with bullous skin diseases were analysed by immunochemical techniques including crossed immunoelectrophoresis. The results were compared with those obtained in fluid from suction bullae obtained in normal skin in 13 control subjects and synovial fluid from 20 patients with rheumatoid arthritis. Abnormal fibrinogen degradation products identical with those found in synovial fluid from patients with rheumatoid arthritis were detected in exudates from each of the patients with bullous dermatoses, whereas significantly smaller amounts of fibrinogen antigenic material were detected in fluid obtained by suction. The fibrinogen antigenic material demonstrated in exudates from pathological bullae, immunochemically similar to that found in rheumatoid synovial fluid, indicates that the presence of these products reflects the more general features of an inflammatory exudate.

The peripheral stromal fibronectin (FN) staining patterns of invasive breast carcinomas (IBC) from 77 women were compared to the aggressivity of the tumors, which in each case had been determined through a complete clinical follow-up and autopsy investigation. Polyclonal, monospecific rabbit antibody to human FN was applied on formalin-fixed, paraffin-embedded tissue sections using the peroxidase-antiperoxidase staining technique. An FN-positive staining reaction was defined as a constant, diffuse, or pericellular demarcation of FN-positive fibers surrounding tumor cells at the invasive border. In lack of such a staining pattern, FN-negative staining was recorded. The FN-positive staining reaction was significantly associated with a low metastatic potential and appeared in a multivarians analysis to be an excellent prognostic factor, which surpassed other known parameters, such as clinical stage, histological type or grade, and lymph node status. 27 out of 31 women, who died without evidence of metastatic spread, had FN-positive IBC (87%) in contrast to women with metastatic disease, where only 15 out of 46 had FN-positive tumors (33%). An extensive histopathological examination of the contralateral breast revealed in this latter group a high rate of second primaries (22/46), which might have been responsible for the metastatic spread. If these women with bilateral IBC were excluded, only three metastasizing tumors with a FN-positive staining pattern remained, suggesting that the prognostic value of the FN-staining pattern along the invasive border of IBC might be even higher than anticipated from this study.

The primary inhibitor of plasmin in human plasma was purified by a four-step procedure involving fractional (NH(4))(2)SO(4) precipitation, ion-exchange chromatography on a column of DEAE-Sepharose CL-6B and affinity chromatography on both a plasminogen-CH-Sepharose 4B column and a column of 6-aminohexanoic acid covalently coupled through the carboxylate function to AH-Sepharose 4B. No impurities in the final preparation could be detected when tested by immunoelectrophoresis against a range of specific antisera or against rabbit anti-human serum. On polyacrylamide-gel electrophoresis the inhibitor preparation showed a single band. The dissociation constant for the inhibitor-plasminogen complex was determined to be approx. 3mum at pH7.8. The reactions of the inhibitor with human plasmin and with bovine trypsin were studied. Comparison of the results obtained confirms the hypothesis previously presented, namely that the reaction of the inhibitor with plasmin involves at least two steps, the initial rapid formation of an enzyme-inhibitor complex followed by a slow irreversible transition to another complex. The results also indicate that the reaction of the inhibitor with trypsin involves just a single, irreversible step, so that this reaction seems to be less complicated than that of the inhibitor with plasmin. The ways in which 6-aminohexanoic acid influences the reactions were studied. The same value for the dissociation constant (approx. 26mum) for 6-aminohexanoic acid is obtained for both its effect on the reaction of the inhibitor with trypsin and for competitive inhibition of trypsin. The inhibitory effect of 6-aminohexanoic acid thus seems to be due to its blocking of the active site of trypsin. In contrast with this, the inhibitory effects of l-lysine and 6-aminohexanoic acid on the inhibitor-plasmin reaction occur at concentrations much too low to affect the active site of plasmin. The possible dependence of the reaction of the inhibitor with plasmin on a second site(s) on plasmin is discussed.

Normal synovial membranes and synovial membranes from patients with classic rheumatoid arthritis were investigated for the presence of fibrin and fibronectin by an indirect immunoperoxidase technique. In normal synovial membranes, fibronectin was found around the monolayer of the synovial lining cells. Staining was most intense on the surface and beneath the lining cells, but not detectable in the cytoplasm. Fibronectin was also found in the cytoplasm of the endothelial cells. No staining for fibrin was found in the normal synovial membrane. In synovial membranes from patients with rheumatoid arthritis, large amounts of fibronectin were found around the multilayer of synovial lining cells, in the cytoplasm of the endothelial cells, and in argyrophilic fiber-rich connective tissue. In superficial areas denuded of synovial lining cells, high amounts of fibronectin were found incorporated in fibrin. In some areas with noninjured synovial lining cells, fibrin was also found, but in this case no fibronectin was incorporated. No fibronectin was found in connective tissue in areas with infiltration of inflammatory cells. After treatment of normal and rheumatoid synovial membranes with hyaluronidase, fibronectin was still present around the lining cells but the staining was found to be more distinct. This study relates the presence of fibrin and fibronectin in the rheumatoid synovial membrane to the high amount of these proteins, recently described, in rheumatoid synovial fluid. It also suggests that fibronectin present in the synovial membrane is produced and secreted by the endothelial cells.

In 20 consecutive rheumatoid arthritis patients, 14 women and 6 men, age 26--76, average 62 years, the concentration of the recently found "primary plasmin inhibitor" and phase proteins was estimated in plasma and synovial fluid. In 12 patients a complex between the inhibitor and plasmin could be demonstrated by crossed immunoelectrophoresis into immunoglobulins against the primary plasmin inhibitor and immunoglobulin against plasminogen. Only free inhibitor was found in corresponding plasma. All plasminogen present in synovial fluid could be activated to plasmin upon addition of urokinase (24 nM/1). In those patients where enzyme-inhibitor complex in synovial fluid was present, a higher concentration of phase proteins in synovial fluid was found, indicating an increased degree of inflammation despite identical scores in the Lansbury clinical index in the two groups. From these experiments it was concluded that the fibrinolytic capacity in rheumatoid synovial fluid is not decreased. It is suggested that the fibrin-like material in synovial tissue and upon the synovial membrane is a poor substrate for plasmin.