Lack of effect in desensitization with intravenous immunoglobulin and rituximab in highly-sensitized patients

Background: We aimed to investigate the effects of intravenous immune globulin (IVIG) and rituximab desensitization treatment on kidney transplant rate and blood gene expression profiles by microrarrays. Methods: We enrolled patients with PRA levels >50% and on the deceased-donor waiting list for >5 years. Patients received IVIG (2.0 g/kg) on day 0 and 30; and rituximab (375 mg/m2) on day 15. The antibodies with mean fluorescence intensity (MFI) values > 5,000 were reported to UNET as unacceptable antigens. The gene expression profiles of blood samples collected in PAXGene tube were studied by Affymetrix HuGene 1.0 ST expression arrays. Results: 40 of the 415 patients (10%) on the waiting list were eligible for desensitization treatment and 11 completed the treatment. While 15 of the remaining 29 patients (52%) received a transplant without therapy, only 2 of the 11 desensitized patients (18%) received transplant during a median follow-up of 217 days. While there were no statistically significant difference in demographics, desensitized patients had higher cPRA values (97% vs. 77%, p=0.0005) and more number of unacceptable antigens (39 vs. 10, p=0.0001). There was no significant change in the mean number of unacceptable antigens (39 22 versus 39 23) or reduction in the mean MFI values (11,333 3,133 vs 11,289 3,386). Analysis of genes chosen as significantly differentially expressed revealed downregulation of genes involved in B cells and immune system (CD79a, B and T lymphocyte associated transcript, B cell scaffold protein, CD22, CXCR5, fas apoptotic inhibitory protein). Gene set enrichment analysis using Pathogenesis Based Transcripts created by Edmonton Group demonstrated significant downregulation of B cell associated (p=0.04) and immunoglobulin transcripts (p=0.03). Conclusion: Although, desensitization with IVIG and rituximab decreases the expression of B cell and immunoglobulin associated transcripts, it was not successful in increasing kidney transplant rate or in decreasing the number of unacceptable antigens.

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