Cellular Kinetics and VH studies
The majority of circulating CLL cells do not proliferate, however there is a small proliferative compartment in the lymph nodes and bone marrow that contains activated, dividing CLL cells. In addition, the accessory signals derived from the microenvironment play an essential role for the neoplastic cell survival and expansion. The CLL clones have a dynamic balance between birth and death.
Our preliminary data suggests that we can identify the small fraction of cells that proliferate within CLL clones by immunofluorescence using CD19, CD5, and CXCR4. Specifically, we have found that the CD19+CXCR4low/CD5high subset of CLL clones is enriched for cells that express CD38 and Ki-67, both markers of cellular activation in CLL. Furthermore this fraction contains the highest incorporation of 2H in patients that have entered the CRC "heavy water" (2H2O) studies (CRC Clinical Trial). Therefore we propose to define an extended phenotype for the "proliferative compartment" by adding additional makers to the CD19+CXCR4low/CD5 high panel. In particular, we will check CD11a, CD23, CD27, CD49d, and CD52. By these studies, we will attempt to identify those members of CLL clones that are most likely to undergo genetic evolution to more dangerous variants because of the heightened proliferative rate of this very small subgroup. The Tissue Core will include these proliferative markers in the standard CLL immunofluorescence panel.
The clinical course of patients with Chronic Lymphocytic Leukemia (CLL) is heterogeneous. While some patients have aggressive disease requiring therapy within a relatively short time after diagnosis, others have indolent, asymptomatic disease that might not require therapy for many years. Several CLL cell characteristics are associated with relatively aggressive disease. These include absence of IgVH somatic mutations, functional loss of P53, deletion of 11q23, high expression of CD38 and ZAP-70, or multiple cytogenetic abnormalities. The expression of unmutated IGHV is a predictor of aggressive disease. We are currently testing the hypothesis that the reason that CLL patients with mutated IGHV have a better clinical outcome is that somatic mutations lead to a structural change in the antigen-binding sites of the BCRs of such cases. There may be a direct correlation between the number of replacement somatic mutations and clinical outcome; similarly, silent mutations should not have an impact on patient survival. We are performing a detailed analysis of the thousands of IGHV sequences obtained from the Tissue Core to explore this and other hypotheses.
Damle RN, Temburni S, Calissano C, Yancopoulos S, Banapour T, Sison C, Allen SL, Rai KR, Chiorazzi N. CD38 expression labels an activated subset within Chronic Lymphocytic Leukemia clones enriched in proliferating B-cells. Blood 2007; 110: 3352-3359 [08/07/07 Epub ahead of print]
Catera R, Silverman GJ, Hatzi K, Seiler TM, Didier S, Zhang L, Herve M, Meffre E, Oscier DG, Vlassara H, Chen Y, Allen SL, Rai KR, Chu CC, Chiorazzi N. Chronic lymphocytic leukemia cells recognize conserved epitopes associated with apoptosis and chemical modifications. Mol Med 2008; 14: 665-674
Chu CC, Catera R, Hatzi K, Yan X-J, Zhang l, Wang XB, Fales HM, Allen SL, Kolitz JE, Rai KR, Chiorazzi N. Chronic lymphocytic leukemia antibodies with a common stereotypic rearrangement recognize non-muscle myosin heavy chain IIA. Blood 2008; 112: 5122-5129 [09/23/08 Epub ahead of print]
Seiler T, Woelfle M, Yancopoulos Y, Catera R, Li W, Hatzi K, Moreno C, Torres M, Paul S, Dohner H, Stilgenbauer S, Kaufman MS, Kolitz JE, Allen SL, Rai KR, Chu CC, Chiorazzi N. Characterization of structurally-defined epitopes recognized by monoclonal antibodies produced by Chronic Lymphocytic Leukemia B-cells. Blood 2009; 114: 3615-3624. [Aug 18, 2009 Epub ahead of print]
Calissano C, Damle RN, Hayes G, Murphy EJ, Hellerstein MK, Sison C, Kaufman MS, Kolitz JE, Allen SL, Rai KR, Chiorazzi N. In vivo intra- and inter-clonal kinetic heterogeneity in B-cell Chronic Lymphocytic Leukemia. Blood 2009; 114: 4832-4942. [Sep 29, 2009 Epub ahead of print]
Darzentas N, Hadzidimitriou A, Murray F, Hatzi K, Josefsson P, Laoutaris N, Moreno C, Anagnostopoulos A, Jurlander J, Tsaftaris A, Chiorazzi N, Belessi C, Ghia P, Rosenquist R, Davi F, Stamatopoulos K. A different ontogenesis for Chronic Lymphocytic Leukemia cases carrying stereotyped antigen receptors: molecular and computational evidence. Leukemia 2010; 24:125-132. [Sep 17, 2009 Epub ahead of print]
Chu CC, Catera R, Zhang L, Didier S, Agagnina BM, Damle RN, Kaufman MS, Kolitz JE, Allen SL, Rai KR, Chiorazzi N. Many Chronic Lymphocytic Leukemia antibodies recognize apoptotic cells with exposed non-muscle myosin heavy chain IIA: Implications for patient outcome and cell of origin. Blood 2010: in press.