A novel human homologue of Escherichia coli, yeast and plant 1-acylglycerol-3-phosphate acyltransferase has been isolated from U937 cell cDNA. Expression of the cloned sequence in 1-acylglycerol-3-phosphate acyltransferase-deficient E. coli resulted in increased incorporation of oleic acid into cellular phospholipids. Membranes made from COS7 cells transfected with the cDNA exhibited higher acyltransferase activity towards a range of donor fatty acyl-CoAs and lysophosphatidic acid. Northern-blot analysis of the cDNA sequence indicated high levels of expression in immune cells and epithelium. Rapid amplification of cDNA ends revealed differentially expressed splice variants, which suggests regulation of the enzyme by alternative splicing. This cDNA therefore represents the first described sequence of a mammalian gene homologous to non-mammalian lysophosphatidic acid acyltransferases.

The effect of hydrophobicity on antibody aggregation is well understood, and it has been shown that charge calculations can be useful for high-concentration viscosity and pharmacokinetic (PK) clearance predictions. In this work, structure-based charge descriptors are evaluated for their predictive performance on recently published antibody pI, viscosity, and clearance data. From this, we devised four rules for therapeutic antibody profiling which address developability issues arising from hydrophobicity and charged-based solution behavior, PK, and the ability to enrich for those that are approved by the U.S. Food and Drug Administration. Differences in strategy for optimizing the solution behavior of human IgG1 antibodies versus the IgG2 and IgG4 isotypes and the impact of pH alterations in formulation are discussed.

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A reverse hemolytic plaque assay utilizing protein A-coated sheep red cells and a specific rabbit anti-rat IgE preparation has been adapted for the enumeration of rat IgE-secreting cells derived from the IR-162 rat plasmacytoma and from rats infected with Nippostrongylus brasiliensis. Under optimal conditions, approximately 10-15% of the viable plasmacytoma cells were scored as plaque-forming cells. In rats infected with 5000 Nippostrongylus brasiliensis larvae, a maximum of 2 x 10(6) IgE-secreting cells were found in the mesenteric lymph nodes, and no IgE plaque-forming cells in their spleens. The kinetics of the mesenteric lymph node plaque-forming cell responses closely coincided with total serum IgE levels, with maximum responses occurring 15-16 days after infection. There was a high degree of correlation between the mesenteric lymph node IgE plaque-forming cell responses and total serum IgE levels of individuals rats. It was concluded that the IgE-secreting cells in the mesenteric lymph nodes contributed, in a large way, to the elevated levels of IgE found in the circulation of these rats.

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