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ANTIBODIES AGAINST MICA ARE FOUND IN ADDITION TO ANTI HLA ANTIBODIES IN PATIENTS WHO REJECT A TRANSPLANT.
K. Mizutani, J. D. Bignon, M. Hourmant, A. Cesbron, J. P. Soulillou, R. N.J. Shih, R. Pei, J. Lee, M. Ozawa and P. Terasaki. Terasaki Foundation Laboratory; Nantes and One Lambda,Inc..
We examined the serum of patients who rejected a kidney transplant for antibodies(Abs) against MICA, since in some patients who reject a transplant, no Abs to HLA could be found.
The sera of 108 patients who rejected a kidney were compared against sera of 65 patients who had functioning transplants. HLA Abs were first examined by flow cytometry. The sera were also tested by cytotoxicity against MICA recombinant cell lines having the following specificities: 1,2,4,7,8,12,17, and 18.
69% of rejected transplants had HLA Abs compared to 29% of functioning kidneys. Thus a significantly higher proportion of patients who rejected a transplant had HLA Abs (p<.0001). When examined separately for MICA Abs in HLA negative patients, 44% of rejected transplants had Abs compared to 9% of functioning grafts (p= .0004). Consequently, overall, there was a significantly higher percentage of patients who had HLA and/or MICA Abs among failed patients (82%) as compared to functioning patients (35%) (p<.0001). No MICA Abs were found in the sera of 80 control normal subjects.
In conclusion, Patients who rejected a kidney transplant had MICA Abs in addition to HLA Abs in a higher frequency than patients with functioning transplants. We postulate that those who have functioning grafts with Abs are those who are currently in the process of slowly rejecting their transplants.