Presentation on theme: "Immunogenetica della LLC: implicazionui patogenetiche e prognostiche mediante analisi del gene IGHV1-69 Francesco Forconi Ematologia e Trapianti Università"— Presentation transcript:
Immunogenetica della LLC: implicazionui patogenetiche e prognostiche mediante analisi del gene IGHV1-69 Francesco Forconi Ematologia e Trapianti Università di Siena Orvieto, Palazzo Coelli 21 Novembre 2009
IGHV-D-J rearrangement HFR1HFR2HFR3 HCDR1HCDR2 HCDR3 IGHVIGHJIGHD N Region Hypervariable Region IGH Variable region 51 IGHV genes27 IGHD genes6 IGHJ genes
Antigen Ig IgM IgD Ig MUTAZIONI SOMATICHE Cellula B memoria Cellula B immatura Cellula B naive Midollo Osseo Organi linfoidi secondari/ Marginal Zone IgM IgD IgG UM-CLL 40 % M-CLL 60%
Sopravvivenza e stato mutazionale dei geni IGHV Hamblin, T. J. et al. Blood 1999;94: mesi 293 mesi Damle, R. N. et al. Blood 1999;94: anni 9 anni
Shared sequence stereotypic characteristics of the HCDR3 suggest antigen selection of the leukemic clones
Top 10 in CLL Murray et al BLOOD, 2008 (111).
Selective stimulation of the B cell of origin (?) Antigenic drive continuing following transformation (?) Are Stereotypes CLL-specific?
IGHV alleli di cui i più frequenti IGHV1- 69*01, *02, e *12 (riconosciuti dallanticorpo anti-51p1 G6) Infrequente nella popolazione B del sangue periferico da analisi molecolari (Lipsky: <1%) 13% di tutte le CLL 30% delle UM-CLL 227/259 (88%) cases >98% homology to germline alleles Dal 47% al 55% delle CLL stereotipate Nella CLL mediana dei casi 1-69 è 69 anni N=214
51p1-IGHJ6 rearrangements expressed in the normal B cell repertoire
Comparison of the HCDR3 sequences of CLL and normal B cells in the 51p1-IGHJ6-derived subset 5.
4.8% of all B-cells. CD27-negative, indicative of naïve B cells. IgM+ IgD+ CD23+ CD5- CD38+ (as in G6-ve naïve B-cells). A small percentage of CD5+ B cells, not found in the memory B- cell subset. CD38 expression was similarly high in naïve and G6-positive populations. IgK (65%) : IgL (35%) comparable to normal B cells and 51p1+ve CLL (data not shown). Absence of activation markers (CD25 and CD69). G6-positive (IGHV p1-expressing) B- cells are part of the conventional resting naïve B-cell population.
Are Stereotypes CLL-specific? by focusing only on the IGHV1-69-derived sequences combined to IGHJ6 in age-matched normal subjects, we have found Stereotypic sequences of several of the major subsets described in CLL and of new potential subsets in > 33% sequences cloned from normal donors. it is possible that this conserved sequences are a likely source of transformation to U-CLL and that they derive from the naïve B-cell repertoire. Little similarity in the HCDR3 junctional amino acids between cases of CLL and little similarity within normal B cells
How does antigenic stimulation would continue following transformation? HCDR3 driven clustering to identify prognostic subsets Stamatopoulos, K. et al. Blood 2007;109:
Subset 1 CRO AVIANO
Events/N5-year riskSE IGHV4-39 6/ %13.5% No IGHV / %1.1% p<.001 No IGHV4-39 IGHV4-39 Rossi, Clinical Cancer Research 2009 No IGHV4-39/stereotypic HCDR3 IGHV4-39/stereotypic HCDR3 No IGHV4-39/no stereotypic HCDR3 IGHV4-39/no stereotypic HCDR3 5-year riskp IGHV4-39/stereotypic HCDR368.7%.003 IGHV4-39/no stereotypic HCDR30 No IGHV4-39/stereotypic HCDR39.9%.005 No IGHV4-39/no stereotypic HCDR34.2% IGHV4-39 and transformation to Richter Sydrome
IGHV1-69 & progression Stamatopoulos, K. et al. Blood 2007;109:
HCDR3 length in CLL HCDR3 length in 1-69
Summary By investigating the IGHV1-69-J6 repertoire we can observe that CLL-specific HCDR3 are present in the normal individuals The subsets with different clinical behavior may rely on (super)antigen stimulation. However, it remains to be demonstrated that stimulation occurs through specific CDR3 interaction. Lack of different behavior (CLL progression and overall survival) between stereotyped and non stereotyped UM- CLL using IGHV1-69 point to antigen stimulation via CDR3-independent antigen. Clinically, mutational status keeps being confirmed as the relevant tool to stratify progression risk in CLL
p66Shc levels and clinical behavior of U-CLL and M-CLL Capitani et al, submitted 2009
Siena Emanuele Cencini Elisa Sozzi Nagaja Capitani Cosima Baldari Novara Davide Rossi Gianluca Gaidano Aviano Riccardo Bomben Valter Gattei Bellinzona Andrea Rinaldi Francesco Bertoni Niguarda Milano Silvio Veronese Marco Montillo Roma Dimitar Efremov Luca Laurenti Giovanni Del Poeta Modena Roberto Marasca Torino Marta Coscia Massimo Massaia Southampton Kathy Potter Freda K. Stevenson Salonicco Kostas Stamatopoulos