B- lineage non-Hodgkin's lymphoma cells against clonogenic B-lineage acute lymphoblastic leukemia as well as immunotoxins of human B-cell ontogeny and the efficacy of anti-CD40 Temporal association of CD40 antigen expression with discrete stages

summary, we examined the temporal association of the orderly acquisition and expression of CD40/Bp50 B-lineage differentiation antigen with discrete stages of development in human B-cell ontogeny. This study expands and clarifies the current knowledge about the correlated expression of CD40 and other B-lineage surface antigens at the earliest stages of human B-cell ontogeny. Multiparameter flow cytometric analysis of CD40 expression on immunologically distinct subpopulations of B-lineage lymphoid cells reflecting discrete maturational stages within the B-precursor pathway com- bined with analysis of sequential acquisition and expression of B-lineage lymphoid differentiation antigens on FBM BCPs showed that the acquisition and surface expression of CD40 antigen in human B-cell ontogeny is (1) developmen- tally programmed and reflects a distinct stage of differentia- tion and (2) occurs very early following the expression of CDlO and CD19 antigens and preceding the rearrangement oEIg genes as well as the acquisition of CD20, CD21, CD22, CD24, and sIgM. Our findings also show that the CD40 antigen is expressed on clonogenic B-lineage leukemia and lymphoma cells. Our study further demonstrates that an antLCD40 immunotoxins effectively kill clonogenic cells from B-lineage ALL as well as B-lineage NHL patients. The