Background: Since the first attempts of kidney transplant, the inflammation mediated by T lymphocytes was considered one of the most important processes implicated in graft rejection but, multiple acute and chronic graft rejects revealed that the inflammation process is not singular and humoral mechanisms may play a role in the development of chronic vascular rejection.

Material and methods: We evaluated 500 Romanian patients registered on the kidney transplant waiting list. We performed anti–HLA class Ⅰ and class Ⅱ antibodies screening and identification. Laboratory tests were performed at Centre for Immunogenetics and Virology, Clinical Institute Fundeni, Bucharest, Romania. The methods used are represented by ELISA (GTI Diagnosis, USA) and Luminex (Tepnel, USA)

Results: pretransplant evaluation of the subjects illustrates that 145 patients (29%) have been sensitized and 355 patients (71%) have not been sensitized. The most frequent types of anti–HLA antibodies were: A2 (13%), B42 (10%), DR7 and DR11 (13%). Posttransplant, the most cases with de novo antibodies were observed in the first 6 months post transplantation. High serum levels of Il–2Receptor, TNF–alpha and neopterin in post transplant sensitized patients were observed following de novo cytotoxic antibodies occurrence.

Conclusion: post renal transplantation, patients present high risk in developing de novo cytotoxic antibodies, especially those who had HLA mismatch with the donor. These antibodies are predictors for acute graft rejection and for graft failure.