Analysis of human lymphocyte protein expression. I. Identification of subpopulation markers by two-dimensional...

This study provides new knowledge on the changes in protein expression that differentiate the functionally and phenotypically different cells of the human immune system. Purification by flow cytometry of normal lymphocytes (both T and B cells), monocytes and granulocytes, combined with high-resolution two-dimensional polyacrylamide gel electrophoresis, revealed reproducible qualitative and quantitative changes between these cell populations. Characteristic profiles of marker proteins for each cell type were identified. Determination of markers for T lymphocyte subpopulations was achieved by the comparative analysis of normal T cells separated on the basis of CD4 and CD8 expression in combination with the analysis of cells from patients with T cell chronic lymphocyte leukemia. These results suggest that the modulation or regulation of proteins is very strictly controlled in lymphoid differentiation, and that several quantitative and a few qualitative differences can give rise to completely different phenotypes. Thus, instead of detecting numerous random differences among lymphocyte protein patterns, rather stringent regulation of protein expression in each subpopulation was found.