Analysis of Draining Leukocytes from the Abdominal Fluid to Monitor Immune Events after Intestinal Transplantation. Follow Up Report: 2505

Introduction: During intestinal transplant (ITx) operation, intestinal lymphatics are not reconstituted. Consequently, lymph containing trafficking leukocytes drains freely into the abdominal cavity, where this fluid is absorbed by an open drainage system. We have previously reported that the abdominal drainage sample is different from the blood sample in composition of the three major leukocyte populations, lymphocytes, monocytes, and granulocytes and therefore might be useful for monitoring immune events during the first post-operative weeks. In this follow up study, our aim was to correlate changes in fluid cellularity with the occurrence of clinical events. Methods: Seventeen consecutive ITx patients (12 pediatric, 5 adult; 1 liver/intestine, 2 multivisceral, 14 isolated) were included in this retrospective cohort study. Cell composition of the abdominal drainage sample was analyzed by flow cytometry during the first 15 post-ITx days. The correlation between cell parameters (FSC-SSC pattern, CD4/CD8 ratio, CD69 expression in T cells, NK and NKT cells appearance) and clinical complications was evaluated. Results: Cellular pattern varied along the post-ITx period in non-complicated recipients (n = 6) from a mixed leukocyte pattern to an exclusively lymphocytic pattern from the fourth day onwards with predominance of CD4+ T cells (50-80%). In contrary, in samples of patients with intra-abdominal clinical complications, such as bacterial infections (n = 3), rejection (n = 3), or non-infectious inflammatory events (n = 5), we could correlate appearance of granulocytes and natural killer cells with clinical events. In addition, the expression of the early activation marker CD69 was significantly increased on CD4 and CD8 T cells from samples with clinical events. No clear differences in cellular composition or CD69 expression between the different clinical complications could be detected. Conclusions: Our results indicate that cell analysis of the draining fluid from intestinal transplant recipients might be useful as a tool to support diagnosis and clinical patient management during the first post-Tx weeks, that are critical due to high incidence of complications. Furthermore, this follow-up study ensures the utility of this method to gain insight into intestinal transplant immunobiology.