DIFFERENTIAL EXPRESSION OF LYMPHOCYTE FUNCTION-ASSOCIATED ANTIGEN (LFA-1) ON PERIPHERAL-BLOOD LEUKOCYTES FROM INDIVIDUALS WITH DOWNS-SYNDROME

We analysed the expression of lymphocyte function-associated antigen L FA-1 on the cell surface of peripheral blood lymphocytes, monocytes an d granulocytes from 20 children with Down's syndrome. No differences i n LFA-1 expression was found within monocytes or granulocytes from eit her normal or Down's syndrome children, however, a clear-cut differenc e was observed on lymphoid cells; Both normal and Down's syndrome lymp hocytes displayed a bimodal pattern of LFA-1 staining by flow cytometr y, with a predominance of cells with low expression in normal populati on, and an increased proportion of lymphocytes with high level of LFA- 1 expression in Down's syndrome children. This difference correlates w ell with the abnormal proportion of T cell subsets and inversion of CD 4/CD8 observed in a majority of our cases, and therefore, it could mer ely reflect the increase of certain T cell subsets normally expressing higher number of LFA-1 molecules. Taken together, our results do not support an abnormally increased expression of leucocytes integrins in trisomy 21 cells, and raise some doubt about the suggested role of the abnormal cellular expression of LFA-1 in the pathogensis of secondary immunodeficiency associated to Down's syndrome.