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Graft-versus-host disease (GVHD) is the major complication occurring after bone marrow transplantation. The severity of GVHD varies widely, with this variation generally being attributed to variation in the degree of disparity between host and donor for minor histocompatibility antigens. However, it is also possible that other forms of polymorphism, such as polymorphisms in immune effector molecules, might play a significant role in determining GVHD severity. In order to investigate this hypothesis, we are studying the genetic factors that influence GVHD development in a murine model. We here report the first results of this analysis, which demonstrate that a locus on Chromosome 1 of the mouse, and possibly also a locus on Chromosome 4, exert considerable influence over the development of one aspect of acute GVHD - splenomegaly - in a parent--F1 murine model. These results demonstrate that non-MHC genes can exert quite significant effects on the development of GVHD-associated pathology and that gene mapping can be used as a tool to identify these loci. Further analysis of such loci will allow identification of the mechanism whereby they influence GVHD and may lead in the future to improved selection of donors for human bone marrow transplantation.

A new technique using oxygen plasma etching was developed for studying the dispersion of filler particles in polymer solids. With this method, the organic polymer matrix is selectively etched from the top surface down into the bulk, revealing the dispersion state of the filler particles upon scanning electron microscopic analysis. A polymer composite, comprised of zinc oxide particles and a linear styrene-n-butylmethacrylate copolymer, was used to investigate the particle dispersion as a function of filler volume fraction. Preliminary data on the effect of a surfactant on filler dispersion is also discussed

SYNOPSIS. Centrifugation for 30–40 seconds at 8,000 g has been used to render monopodial specimens of the large free-living ameba. Chaos carolinensis. These monopodial amebae exhibit obvious torsional movements in the tail. In many cases the posterior ectoplasm assumes the form of a screw with helical ridges forming in place of the more common straight dorsal fins. This finding prompted a re-examination of normal polypodial C. carolinensis, and a majority of these were found also to exhibit torsional movement in the tail and in retracting pseudopodia. These movements suggest that the cytoskeleton of Chaos may have a helical component in its organization.