The journal of allergy and clinical immunology. In practice •
Hypersensitivity reactions (HSRs) to monoclonal antibodies (mAbs) are increasingly frequent as this class of therapeutic agents is rapidly expanding. Immediate and nonimmediate HSRs have been reported with mAbs. Immediate HSRs can be explained by 3 main mechanisms: cytokine release syndrome, IgE-mediated, and IgG-mediated reactions. Importantly, IgE-mediated reactions can occur on first exposure due to preformed specific IgEs, as shown for cetuximab. Almost all patients with an immediate HSR can be safely re-exposed either through desensitization or challenge depending on the severity and mechanism of the initial reaction. An algorithm detailing the general approach to these HSRs and the preferred method of re-exposure is presented in this review. Also, the mAbs that are most frequently implicated in HSRs are discussed individually.
Perry MB, MacLean LL, Gottschalk M, Aragon V, Vinogradov E
Carbohydrate research •
Haemophilus parasuis is a Gram-negative bacterium from the family Pasteurellaceae and a swine pathogen. H. parasuis is found in the upper respiratory tract of piglets and produces Glässer's disease, an invasive disease characterized by polyserositis. H. parasuis contains a short lipopolysaccharide (LPS) or lipooligosaccharide (LOS) reported to play a partial role in interaction with host cells. The presence of capsule has been phenotypically demonstrated in certain H. parasuis strains and its role in virulence has been suggested, but the chemical structure of the surface polysaccharides of this bacterium was unknown. The structure of capsular polysaccharide (CPS) and LOS from virulent strains ER-6P and Nagasaki was studied by NMR spectroscopy, mass spectrometry and chemical methods. CPS from both strains had the same main chain with disaccharide repeating unit, substituted with α-Neu5R-(2-3)-α-GalNAc-(1-P-(strain ER-6P) or α-Neu5R-(2-3)-α-Gal-(1-P-strain Nagasaki) side chains, where R is the N-acetyl or N-glycolyl group. Glycolyl-neuraminic acid is widely found in animal glycoproteins, but it apparently has not been found in bacteria before, and might be important for the biology of this microorganism. Ac and Gc were present in equal amounts in the strain ER-6P but Nagasaki contained only about 20% of Gc substituent. Both strains produced the same LPS of a rough type with a single phosphorylated Kdo linking core and lipid A parts. LOS structure was similar to some strains of H. influenzae and contained a globotetraose terminal sequence.
Michael FS, Brisson JR, Larocque S, Monteiro M, Li J, et al.
Carbohydrate research •
The structures of the core oligosaccharides of the lipopolysaccharides (LPS) from Actinobacillus pleuropneumoniae serotypes 1, 2, 5a and 5b were elucidated. The LPS's were subjected to a variety of degradative procedures. The structures of the purified products were established by monosaccharide and methylation analyses, NMR spectroscopy and mass spectrometry. The following structures for the core oligosaccharides were determined on the basis of the combined data from these experiments. [carbohydrate formula see text] For serotype 1: R is (1S)-GalaNAc-(1-->4,6)-alpha-Gal II-(1-->3)-beta-Gal I-(1-->, and R' is H For serotype 2: R is beta-Glc III-(1-->, and R' is D-alpha-D-Hep V-(1--> For serotypes 5a and 5b: R is H and R' is D-alpha-D-Hep V-(1--> All oligosaccharides elaborated a conserved inner core structure, as illustrated. All sugars were in the pyranose ring form apart from the open-chain N-acetylgalactosamine, the identification of which in the serotype 1 LPS was of interest.
