Dominik Meier¹, Agustina Zambernardi¹, Carolina Rumbo¹, Rodrigo Pappa-Gobi², Ignacio Pérez-Fernández¹, Fernando Chirdo², Guillermo Docena², Gabriel Gondolesi¹, Martín Rumbo²

¹Instituto de Trasplante Multiorganico - Programa de Inmunobiología e Investigación Traslacional en Trasplante, Hospital Universitario - Fundación Favaloro, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina; ²Laboratorio de Investigaciones del Sistema Inmune, Facultad de Ciencias Exactas Universidad Nacional de La Plata, Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina

Introduction: During intestinal transplant (ITx) operation, intestinal lymphatics are not reconstituted. In our first report, we described the factibility to identify cellular population and donor or recipient origin in the abdominal draining fluid post-ITx. The aim of the present study was to correlate variations of draining cells with post transplant clinical events.

Methods: Fourteen consecutive ITx patients were included in the study (11 pediatric, 3 adult; 10 isolated, 2 liver/intestine, 2 multivisceral). Cell composition of the abdominal draining fluid was analyzed periodically during the first 15 post-ITx days by flow cytometry. To exclude blood contamination, only samples having less than 10,000 erythrocytes/ uL were processed. The correlation between cell parameters (FSC-SSC pattern, CD4/ CD8 ratio, CD69 expression on T cells, increased number of NK/ NKT cells) and clinical events was analyzed. Patients were divided into four study groups according with the presence of post transplant complications as follow: Group 1: No-complications (n=3); Group 2: Diarrhea or increased ostomy output (n=4); Group 3: Extra intestinal infections (n=4); Group 4: Others (pancreatitis, intrabdominal hematoma) (n=3).

Results: Group 1: Cellular pattern varied along the post-ITx period from a mixed leukocyte pattern to an exclusively lymphocytic pattern with predominance of CD4+ T cells (30-60%) by day 5 onwards. Different clinical events showed consistent patterns of cellularity. Group 2: Although the shift to a lymphocytic pattern was observed, a clear appearance of granulocytes and monocytes was detected at the time of the clinical complication. Group 3: Postoperative bacterial infections (3/4) had an increase in the draining granulocytes concomitantly or before the diagnosis of the clinical event. In the setting of viral infections (1/4) draining cells had a dominant increase in monocytes over granulocytes. Group 4: This group presented similar changes than group 2. In most cases with inflammatory adverse events concomitant increase in proportion of CD69+ T cells, decrease of CD4/CD8 ratio and increase of NK/ NKT cells was observed.

Conclusions: Our results indicate that cell analysis of the draining fluid from ITx recipients might be useful as a tool to predict or to support clinical management. This follow up study support the utility of this method to gain insight into intestinal transplant immunobiology.