MIG/CXCL9 IS SIGNIFICANTLY UPREGULATED IN CULTURES OF FINE-NEEDLE ASPIRATION BIOPSY SAMPLES OF ACUTELY REJECTING KIDNEY TRANSPLANT RECIPIENTS.

Abstract

P999 Aims: Monokine induced by γ-interferon (MIG) /CXCL9 seems to be a very important chemokine that binds to CXCR3. Strong expression of MIG/CXCL9 is found in renal biopsies of patients with several glomerulonephritis but it is not expressed in normal kidneys. MIG/CXCL9 may be expressed by mesangial cells, podocytes and by infiltrating monocytes-macrophages. Analysis of renal biopsies from patients with kidney transplants using cDNA arrays has shown that MIG/CXCL9 gene is regularly upregulated during acute rejection. Previously our group has reported that cultures of fine-needle aspiration biopsy (FNAB) samples synthesize a large group of cytokines and chemokines which are significantly raised pre- and during acute rejection. We report our analysis of MIG/CXCL9 production by FNAB cultures of kidney transplant patients during the early days post-kidney transplantation. Methods: Seventy-for kidney transplants recipients were admitted to our study. They were divided into three groups. Group I, n=34, included recipients treated with calcineurine inhibitors, mycophenolate mofetil and prednisolone. Group II, n=15, included cases treated with calcineurine inhibitors, rapamycin and prednisolone. Both groups remained rejection-free for the first year post-surgery, at least. Group III, n=25, included cases treated with the same regimen as group I but who developed an episode of acute rejection, confirmed by a core renal biopsy and which occurred during the first two weeks post-surgery. FNAB were done in the morning, two hours after the immunosuppressive drugs administration, on day 7 post-surgery in groups I and II and on the first day of acute rejection diagnosis in III. If the patient was dialysis-dependent, FNAB was done on a non-dialysis day. FNAB samples were submitted to culture during 48 hours at a concentration of 5×104 cells/well with autologous serum and IL2 at 10 U/ml. The culture supernatants were collected at 48 hours and kept at -70°C until testing. MIG/CXCL9 was measured by ELISA from R&D, MN, USA, at a 1/10 dilution. Statistics by Kruskal-Wallis ANOVA. Informed consent was obtained from each case. Results: No significant differences were found when comparing the demographic data of donor-recipient pairs from the three groups. Whole blood calcineurin inhibitors were not significantly different while serum creatinine were significantly higher in II and III as compared to I. MIG/CXCL9 values (pg/ml) were (means±SD and lower and upper quartiles) – I: 165.8±216.5 (56 and 159), II: 180.7±195.8 (63 and 206), and III: 1256.3±1590.7 (357 and 1308). MIG/CXCL9 was significantly higher in III than either I (P<0.001) or II (P<0.001), while no difference was observed by comparing I versus II.By using 200 pg/ml as cut-off, the positive predictive value was 80.7% and the negative predictive value was 90.3%. Conclusions: MIG/CXCL9 was significantly upregulated in cultures of FNAB samples from acutely rejecting patients, confirming the importance of this chemokine in human kidney transplant rejection. Contrary to the analysis of other chemokines previously done by our group, rapamycin did not down regulate MIG/CXCL9 synthesis as compared to cases treated with MMF.