Deficiency of the expression of CD45RA isoform of CD45 common leukocyte antigen in CD4+T lymphocytes in children with infantile cholestasis

The immunological background of the pathological changes that appear in inf antile cholestasis (infections, inflammatory process in the liver) is large ly unknown. With the use of double color flow cytometry, we assessed the di stribution of functionally different lymphocyte subpopulations in the perip heral blood of 29 infants with extra and intra-hepatic cholestasis (12 and 17 patients, respectively), aged from 1 to 8.6 months. Control group consis ted of 15 age-matched, healthy infants. We examined: (1) the expression of CD3, CD4, CD8, CD19 lymphocyte surface receptors; and (2) the distribution of lymphocyte subsets with distinctive surface AE characteristics of 'naive ' (CD45RA +) and 'memory' (CD45RO +) cells in both CD4 + and CD8 + cell pop ulations. The surface markers expression was evaluated in terms of percenta ge of positive cells and receptor density. The following changes in the exp ression of lymphocyte surface markers are described: (1) a decrease in the percentage of total CD3 +, CD4 + cells but normal percentage of CD8 + cells and elevated proportion of CD19 + B cells; (2) a reduction of the proporti on of 'naive' CD4 + lymphocytes but normal percentage of 'naive' CD8 + as w ell as 'memory' CD4 + and CD8 + cell subsets; (3) a decrease in density of CD3, CD4 +, CDS receptors, and D45RA isoform in a subset of 'naive' CD4 + c ells. We conclude that deficiency of 'naive' CD4 + T cell subset which poss ess important effector and immunoregulatory functions, and low expression o f certain lymphocyte receptors known to be engaged in T cell activation, po ssibly reflect a defect of cell mediated immunity that may account for vira l and bacterial infections, often observed in infants with cholestasis. (C) 2001 Published by Elsevier Science B.V. All rights reserved.