Detection of cell-adhesion molecules on human liver-associated lymphocytes

Liver-associated lymphocytes (LAL) from human liver are phenotypically and functionally different from peripheral blood lymphocytes (PBL). Phenotypically, they are mainly represented by the CD3+/-CD56+ phenotype and functionally they spontaneously possess lymphokine-activated killer (LAK) activity. In this study we evaluated the expression of cell-adhesion molecules (CAM) which could be involved in LAL contacts with other sinusoidal cells and/or be responsible for the LAK activity. The LAL population was isolated by sinusoidal high-pressure lavage from partial hepatectomies obtained from patients operated on for benign liver disease (n = 6). Surface expression of the beta 2 integrin chains (CD18, CD11a, CD11b, CD11c), as well as that of members of the immunoglobulin superfamily (CD2, CD54, CD56, CD58), were analysed by one or two-colour flow cytometry. Quantitative and qualitative differences were observed in the expression of CAM between LAL and PBL. LAL were characterized by an increase in the percentages of CD11b+, CD54+, CD56+ and CD58+ cells and a decrease in the percentage of CD2+ cells compared to PBL. Fluorescence intensity values for CD2 and CD56 were higher in LAL than in PBL. Moreover, CD11a/CD18 cells presented a bimodal distribution (dim and bright) in both PBL and LAL; whereas these two subpopulations were equally represented in PBL, the number of bright cells was significantly greater (> 80%) in LAL. The increase in CAM expression (percentage of positive cells and intensity of fluorescence) on LAL combined with their increase in natural killer (NK) and LAK activities already reported, support the idea that, at least some, LAL might be, compared to PBL, in an activated state in vivo.