DIRECT MEASUREMENT OF LEUKEMIC CELL TURNOVER (SYNTHESIS AND REMOVAL) IN PATIENTS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. B cell chronic lymphocytic leukemia (B-CLL) cases are clinically heterogeneous since some patients survive for prolonged periods without requiring therapy, while others die rapidly despite aggressive treatment. However at the cellular level, the disease has been considered homogeneous, resulting from the accumulation of a leukemic clone derived from a normal CD5+ B lymphocyte. Data from our group has documented that B-CLL cases are heterogeneous at the cellular level and segregate into at least two subgroups based on the molecular and phenotypic features of the leukemic B cells. This distinction has very significant clinical implications since the patients in the different groups follow strikingly different courses and outcomes. In this protocol, we will determine more precisely how the leukemic cells in these subgroups differ by studying newly diagnosed, untreated B-CLL patients. These studies involve a series of in vitro experiments (Aims 1 & 3) designed to analyze the expression of surface and intracellular markers of cell activation and maturation as well as gene expression profiling. In addition, a series of in vivo experiments (Aim #2) will be carried out to determine if there is a difference in leukemic cell kinetics (proliferation vs. cell death) between the subgroups. These studies involve the ingestion of deuterated water by patients over a 12 week period, with longitudinal analyses of the appearance and disappearance of deuteriated DNA in newly created leukemic cells as a measure of cell turnover. Concomitantly, the kinetics of polymorphonuclear leukocytes and T lymphocytes will be determined. Polymorphonuclear leukocytes will serve as indicators of a rapidly turning over population of normal autologous non-lymphoid cells, and T cells will serve as an autologous normal lymphocyte population that is clonally expanded. We will correlate these in vivo measurments of leukemic and non-leukemic cell kinetics with other currently used clinical markers of B-CLL growth and disease progression. This approach should help to understand differences among patients of the in vivo biology of B-CLL cells, and may represent a more sensitive and rapid method to analyze B-CLL progression than the currently used parameters. This kinetic approach also may to identify new prognostic subgroups of patients.