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Rat elicited anti-carbohydrate xenoantibodies crossreact with cells of multiple species and bacteria

Magdiel Pérez-Cruz, Rafael Máñez, Cristina Costa

Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Barcelona, Spain

Concordant xenografts induce xenoantibodies in rats which are crossreactive with other concordant species. In this study we investigated the pattern of xenoantibody crossreactivity induced by concordant and discordant xenogeneic immunization against different species, microorganisms and whether these antibodies include carbohydrate targets. To this end, Lewis rats were immunized with hamster or pig blood following two different protocols to generate mainly IgM or IgG xenoantibodies. Reactivity to cells of distinct species and microorganisms was determined by flow cytometry. Elicited anti-hamster IgM and IgG xenoantibodies also targeted porcine, rabbit and human lymphocytes, increasing the binding to these cells 12, 5 and 6 fold respectively for IgM, and 5, 2 and 35 fold respectively for IgG. Induced anti-pig IgM and IgG xenoantibodies in rats also reacted to hamster, rabbit and human lymphocytes, augmenting the binding to these cells 5, 2.6 and 4 fold respectively for IgM, and 8, 3.7 and 100 fold respectively for IgG. Elicited rat anti-hamster antibodies also showed crossreactivity to human endothelial cells and to a lesser degree to porcine endothelial cells, whereas rat anti-pig antibodies also demonstrated a major recognition of human endothelial cells. The elicited anti-hamster and anti-pig xenoantibodies also showed increased reactivity to Enterococcus faecalis but not to Escherichia coli, whilst no autoreactivity against rat lymphocytes and endothelial cells was observed. Elicited anti-hamster and anti-pig xenoantibodies increased the reactivity to 216 and 276 carbohydrates, respectively, of the 512 included in a glycan microarray from the Consortium for Functional Glycomics. Antibodies against L-rhamnose appeared responsible for the crossreactivity of elicited xenoantibodies with E. Faecalis and anti-hamster xenoantibodies with porcine endothelial cells. It is concluded that elicited xenoantibodies in rats, either by immunization with concordant or discordant species, include anti-carbohydrate antibodies crossreactive with cells of other species and microorganisms such as E. faecalis.