Three infants with clinical and biochemical features of Zellweger's cerebrohepatorenal syndrome are presented, and the ultrastructural features of successive biopsy and autopsy liver specimens are described. No hepatocellular peroxisomes were found in these patients on routine electron microscopy or electron microscopic histochemistry. In a control group of liver biopsies from 9 patients with other pediatric liver diseases, peroxisomes were readily identifiable in each hepatocyte. Apart from the absence of peroxisomes, the hepatocytes had a remarkably "normal" aspect, even in the final stages of the disease. Mitochondrial abnormalities, which have been the subject of some controversy in this syndrome, were a highly variable and inconstant finding in our cases. We draw attention to another ultrastructural feature of the syndrome, namely the occurrence of large angulate lysosomes, containing conspicuous double lamellae, inside macrophages, which were especially abundant in later stages of the disease. These angulate lysosomes may be of additional value in the ultrastructural diagnosis of Zellweger's syndrome, especially when only poorly preserved liver tissue (e.g., paraffin-embedded or postmortem material) is available, and the absence of peroxisomes is difficult to assess. In these instances, the angulate lysosomes can still be identified with ease.

Epithelial-derived IL-6 and SCF are implicated in differentiation of HMC-1 cells but additional factors are not excluded. As activated primary bronchial epithelial cells also express IL-6 and SCF, it should be considered that these cells are involved in mast cell differentiation within the airways, particularly in diseases where epithelial cells are activated, such as asthma.

Certain complement inhibitors, namely chlorpromazine, suramin, 2-hydroxystilbamidine and chlorophenothiazine sulphonate were tested for their ability to suppress complement deposition and vascular injury at the site of an Arthus reaction. Deposition of complement was suppressed in the order 2-hydroxystilbamidine > suramin > chlorpromazine. All the above mentioned four compounds strongly protected vascular injury as observed by electron microscopic studies. At Arthus reaction sites prepared without drug treatment venules ranged from normal to severely altered and damaged. Discontinuities in endothelial linings varied from small to longer stretches. In the latter situation remaining endothelial cells were degenerated and endothelial remnants did not have an intact basal lamina. After treatment with the above complement inhibitors, at arthus reaction sites some venules appeared normal, whereas others were altered but in all cases the endothelium and its basal lamina remained intact.