The neonatal Fc receptor (FcRn) regulates the serum half-life of both IgG and albumin through a pH-dependent mechanism that involves salvage from intracellular degradation. WT bound strongly to human IgG1. The latter pair also interacted at physiological pH with calculated affinity in the micromolar range. In all cases, binding of albumin and IgG from either species to both receptors were additive. Cross-species albumin binding differences could partly be explained by nonconserved amino acids found within the ␣2-domain of the receptor. Such distinct cross-species FcRn binding differences must be taken into consideration when IgG-and albumin-based therapeutics and diagnostics are evaluated in rodents for their pharmacokinetics.

The relative complement-mediated lytic capability of the IgG subclass isotypes was studied using a matched set of mouse-human chimeric anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies. The subclass pattern was shown to be highly dependent on variations in antigen concentration and to lesser extent on variation in epitope patchiness, antibody binding affinity and complement concentration. In general, the IgG3 subclass was most effective in inducing cytolysis at the different conditions used and only at high antigen concentration did the IgG1 subclass mediated more efficient cytolysis than IgG3. The IgG2 isotype required a relative high antigen concentration to be cytolytic while the IgG4 isotype was not cytolytic at any of the conditions tested. These individual characters of each of the IgG subclasses makes it conceivable that a subtle system of immunoregulation exists among the subclasses.

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Identification of 123 species, belonging to 50 families, used for wound healing in the Bamako region of Mali, was performed in this study. The fifteen species that were most frequently cited by the traditional healers were subjected to chemical and biological studies. Water extracts were subjected to screening for effects on the human complement system in vitro. The monosaccharide composition and the total carbohydrate content of the extracts were also determined. All extracts showed effects on the complement system, but extracts from Biophytum petersianum Klotzsch., Pterocarpus erinaceus Poir, Podaxon aegyptiacus Mont., Stereospermum kunthianum Cham., and Ximenia americana L. had the highest activity. The content of carbohydrate in the extracts varied between 5% and 80% and most of them contained substantial amounts of the monosaccharides arabinose, rhamnose, galactose, glucose and galacturonic acid.