THE NORMAL AND METASTASES-BEARING LIVERS RETAIN VARIOUS SPECIFIC SUBSETS OF LIVE LYMPHOCYTES FROM PORTAL CIRCULATION

Abstract

The liver is among the organs that traplymphocytes flowing through their bloodvasculature. These cells, marginated insinusoids, participate in the liver's anti-viraland anti-tumor processes. The molecularmechanism of this lymphocyte marginationand cooperation with resident sinusoidal cellsremains obscure and inadequately studied dueto the difficulties in obtaining samples ofsinusoidal blood from a living animal. Toovercome these shortcomings, we have workedout an in situ rat liver perfusion model inexsanguinated animals that enablesquantitative observations of blood lymphocytetrapping in sinusoids. The cell populationstrapped by the liver and retained in theperfusing blood were characterized withrespect to their phenotypes and cytotoxicity.Perfused livers, previously washed out ofsinusoidal lymphocytes, halted leukocytesfrom normal perfusing blood. The numbers ofhalted post-perfusion CD5+, CD4+, CD8+,CD56+ (EDI) and MHC class II+ (OX6)subsets did not differ statistically from thepre-perfusion population, which suggestsactive extraction of leukocytes duringperfusion. Moreover, cytotoxicity ofpost- andpreperfusion populations against CC53I andK562 remained at a similar level. The perfusedlivers with CC53I colon adenocarcinomametastases halted higher numbers of theCDI4 and MHC class II+ andfewer ofCDllb+ and CD54+ normal blood leukocytesthan normal livers. The phenotypes of cellsretrieved from sinusoids after perfusion werealmost identical to those obtained prior toperfusion. Interestingly, the post-perfusionpopulations displayed higher cytotoxiccapacity than before perfusion. Takentogether, the in situ liver perfusion methodallows the study of the specificity and kineticsof recruitment of specific populations of hostleukocytes in metastatic tumor tissue andevaluation of their cytotoxicity levels.