Many donor kidneys that are transplanted are rejected by the recipient within ten years after transplantation. One reason for this are immunoglobulin G antibodies (IgG), which act against human leukocyte antigens (HLA), a tissue characteristic on transplants, and cause rejection. As a result, IgG antibodies are biomarkers for an increased risk of later graft loss. Researchers at the Department of Surgery in cooperation with the Center for Pathophysiology, Infectiology and Immunology and the Division of Nephrology at MedUni Vienna, were able to show that IgE antibodies, which have previously been only known to cause allergic reactions, also occur after kidney transplantation.
"This new finding could open up completely new diagnostic options," says transplantation immunologist Thomas Wekerle. "In the future we might be able to better assess the risk of subsequent rejections with the help of these antibodies, which are rather untypical in transplantation. For the first time, the Viennese researchers have succeeded in detecting IgE antibodies after kidney transplantation. Wekerle: "IgE is a very special antibody and - compared to IgG, for example - difficult to measure."
IgE antibodies are usually known for their important role in the development of allergies. For example, immunoglobulins E are directed against otherwise harmless antigens such as pollen, which can trigger an allergic reaction.
"In transplantation a different type of IgE antibody occurs which targets tissue characteristics of the donor kidney," said Andreas Farkas, the first author of the study he conducted during his PhD studies at MedUni Vienna. This was also clearly shown in comparison with the "allergy IgE". "IgEs cause local inflammation and, this is our current hypothesis, could be potentially involved in the subsequent rejection of the organ together with the IgG antibodies."
This could open up completely new therapeutic options and preventive measures. While it has not yet been possible to achieve long-term immunotolerance of IgG antibodies after transplantation, Rudolf Valenta and his team from the Department of Pathophysiology and Allergy Research at MedUni Vienna were able to show in a study published last year that there is a way of removing IgE antibodies from the blood.
The "IgEnio" column was developed for this purpose. With the help of this specific disposable adsorber for the treatment of IgE-induced diseases, the IgE level in the blood plasma is reduced by passing the blood of the affected person through a "column" in which the IgE antibodies adhere - namely by means of sepharose particles which are occupied with IgE capture proteins. These bind the IgE in the column and practically suck it off as it flows through during "blood washing". If follow-up studies already in progress show that IgE is involved in the rejection, it would also be conceivable to use this therapeutic removal of IgE in transplant patients.