We have applied the highly sensitive method of randomly-primed PCR ("differential display") to a comparative analysis of gene expression in the human pre-B cell line OB5 and the clonally-related immature B cell line 1E8. Three novel gene fragments, 3, 5 and 7, have been isolated which are differentially expressed in these leukemic cell lines. To examine gene expression in normal B lineage cells, blood and bone marrow mononuclear cells were sorted on the basis of CD34, CD19, CD20, slgM, and slgD expression into the following subpopulations: "stem cells" (CD34+/CD19-), pro-B cells, pre-B I and II cells, and immature and mature B cells. By RT-PCR, gene 3 exhibits the most restricted expression, being detected only in the pre-B II cells. Gene 5 is expressed in the stem cell fraction and in the pre-B I and II cells. Gene 7 is expressed from the stem cell stage to the pre-B cell I stage of development. Full-length cDNA clones corresponding to these gene fragments are being isolated in order to gain clues to gene function. Initial analysis of one clone obtained by RACE-PCR suggests that eene 5 represents a novel splice variant of a regulatory subunit of protein phosphatase 2A. |.