In order to investigate the antigen profile in human lymphatic vessels when compared with blood vessels, postmortem retrograde lymphangiography was done via the thoracic duct on six patients. Formalin fixed, paraffin embedded tissue was stained immunohistochemically for Factor VIII-Related antigen (F VIII R:Ag), with Ulex Europaeus 1 lectin (UEA-1) and for laminin. The results show that the endothelium of blood vessels and lymphatics at all levels of the lymphatic system react positively following staining for Factor VIII-R:Ag and with UEA-1 lectin. The staining for F VIII R:Ag was generally weaker in the endothelial cells lining lymphatic vessels. Staining for the basement membrane component laminin can be used to distinguish lymphatic capillaries and smaller lymphatic collecting vessels from blood vessels.

Insulin-like growth factor II (IGF-II) is expressed and secreted by the choroid plexus and has been suggested to act as a trophic factor in the adult mammalian central nervous system. The aim of the present study was to investigate whether IGF-II has an autocrine role in the choroid plexus. Using in situ hybridization we demonstrate that IGF-II is primarily expressed in the epithelium of adult rat choroid plexus. Conditioned medium from primary cultures of purified rat choroid plexus epithelial cells, intact choroid plexus tissue, as well as rat CSF, displaced IGF-II binding to a 23 HMM melanoma cell line in an IGF-II radioreceptor assay. The presence of IGF-II and IGF binding protein-2 in conditioned medium was shown by Western immunoblot. The mitotic activity in choroid plexus epithelial cell cultures was quantified by immunohistochemical staining of bromodeoxyuridine incorporated into cell nuclei. A monoclonal antibody towards IGF-II inhibited cell division by 35%, while IGF-I increased the number of stained nuclei by 75%. Basic fibroblast growth factor stimulated cell division at low concentrations, but had no effect at high concentrations. Growth hormone had no effect. We conclude that IGF-II in the choroid plexus could have an autocrine role in the regulation of choroid plexus epithelial cell growth.

Formalin-fixed, paraffin-embedded material from 15 haemangioendotheliosarcomas and eight malignant haemangiopericytomas was stained with an immunohistochemical technique for the presence of factor VIII-related antigen (F VIII-RAg), actin, laminin and for reactivity with the lectin Ulex europaeus I (UEA-I). Haemangioendotheliosarcomas stained with both F VIII-RAg and UEA-1; however, UEA-I was found to be the more sensitive of the two, reacting also with the poorly differentiated tumours. Haemangiopericytomas reacted negatively with UEA-I; surprisingly, some of these tumours exhibited a weak positivity in staining for F VIII-RAg, possibly supporting the theory about intermediate forms between haemangioendotheliosarcomas and haemangiopericytomas. Laminin was found in most of the haemangioendotheliosarcomas and was useful in illustrating their vascular growth pattern. Haemangiopericytomas also reacted positively for laminin, but the intensity of staining was less pronounced. Positive staining for actin was demonstrated in both tumour types.

Background. Insulin‐like growth factor II (IGF‐II) is synthesized in the normal brain of adult humans predominantly in the choroid plexus and meninges and is secreted in the cerebrospinal fluid. The authors measured IGF‐II transcripts and peptides in biopsy specimens from human intracranial tumors including astrocytomas, glioblastomas, and meningiomas. Methods. The presence of IGF‐II mRNA was analyzed in 12 human brain tumors by Northern analysis of total RNA extracted from tumor biopsies and by in situ hybridization of tissue sections. The amount of immunoreactive IGF‐II was determined by radioimmunoassay of tumor extracts. Results. Northern analysis of RNA from four meningiomas showed IGF‐II mRNA of 6.0, 4.8, and 2.2 kb, and in situ hybridization revealed that meningioma tumor cells contained IGF‐II mRNA. In contrast, biopsy specimens from four astrocytomas, one oligoastrocytoma, and four glioblastomas showed no IGF‐II mRNA. Radioimmunoassay of IGF‐II in tumor extracts showed that all tumors contained IGF‐II (40–160 ng/g tissue). Two meningiomas contained the highest amounts of IGF‐II (144 and 160 ng/g tissue). Conclusions. IGF‐II mRNA is present in higher amounts in benign meningiomas than in malignant glioblastomas and astrocytomas, whereas the content of immunoreactive IGF‐II is similar. On the basis of these findings, the authors believe that IGF‐II may be involved in growth regulation of meningiomas.

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