Over 20% of Patients with Chronic Lymphocytic Leukemia Carry Stereotyped Receptors: Pathogenetic Implications and Clinical Correlations.

Abstract

Chronic lymphocytic leukemia (CLL) immunoglobulin repertoire is biased. Furthermore, subsets of closely homologous (“stereotyped”) complementarity-determining region 3 (CDR3) sequences were recently described in CLL patients. In the present study, we evaluated the frequency and characteristics of these homologous subsets in a cohort of 916 CLL patients. We report that 201 cases (21.9%) expressed IGHV genes which belonged to one of 48 different subsets of sequences with stereotyped heavy chain (H) CDR3, of which only ten have been reported previously. Within each stereotyped HCDR3 subset, the IG sequences might show the usage of identical or different IGHV genes. In the latter case, the IGHV genes most often belonged to the same IGHV subgroup or clan or carried homologous HCDR1. Each subset included up to 20 cases. A similar proportion of HCDR3 restriction (80/462 cases; 17.3%) was found among public-database CLL sequences; comparison to 6430 non-CLL public database IGHV-D-J sequences showed that this is a “CLL-related” feature. In our series, the chance of belonging to a subset was even (p<0.001) higher for unmutated IGHV sequences (35%); furthermore, it exceeded 30% in cases using selected IGHV genes (e.g., IGHV3-21/1-69/1-2/1-3/4-39/3-48). Database and literature searches revealed that 64/916 CLL cases belonging to seven different subsets displayed HCDR3 homology with various autoantibodies, including rheumatoid factors and anti-cardiolipin antibodies. In our series, CLL cases with selected stereotyped IGs were also found to share unique biological and clinical features. In particular, cases expressing stereotyped IGHV4-34/IGKV2-30 B cell receptors (BCRs) were of significantly younger age and followed a strikingly indolent disease, whereas those expressing, IGHV3-21/IGLV3-21 BCRs experienced an aggressive disease, regardless of IGHV mutation status. Furthermore, among patients expressing unmutated IGHV1-69 genes, we identified a subset (IGHV1-69/IGHD3-10/IGHJ6) with higher overall survival (OS) compared to another subset (IGHV1-69/IGHD2-2/IGHJ6) with significantly shorter OS (log Rank test=0.05). In conclusion, the unique, “CLL-biased” molecular features of stereotyped HCDR3 sequences suggest a role for antigen not only in driving the cell of origin but also in determining the clinical features and outcome for at least some CLL patients. Considering the clinical-biological associations with certain subsets, it is conceivable that future therapeutic decisions should be based not only on mutational status of IGHV genes but also on individual HCDR3 characteristics.

B‐cell receptor, clinical course and prognosis in chronic lymphocytic leukaemia: the growing saga of the IGHV3 subgroup gene usage

“…IGHV3-21 was the first IGHV gene recognized to mark a CLL subset with very poor outcome, although usually bearing a M IGHV gene configuration (Tobin et al, 2003;Stamatopoulos et al, 2007;Bomben et al, 2009). Expression of IGHV3-23 was similarly indicated as an additional marker of poor prognosis in CLL (Krober et al, 2002); such a suggestion was then abandoned and, only recently, reconsidered as a feature capable of refining the prognostic assessment in the context of M CLL (Bomben et al, 2010b).…”

“…Finally, the infrequent phenomenon of spontaneous regression in CLL has been associated with usage of genes belonging to the IGHV3 subgroup, such as IGHV3-30 (Del Giudice et al, 2009). The relationship between mutational load and prognosis of these IGHV3-expressing CLL, in comparison with the canonical UM and M CLL, is illustrated in Fig 1. Expression of IGHV3 subgroup genes and poor prognosis in CLL CLL expressing the IGHV3-21 gene A peculiarity of IGHV3-21-expressing CLL is the highly heterogeneous geographical distribution of this CLL subset (Tobin et al, 2002(Tobin et al, , 2003(Tobin et al, , 2004Ghia et al, 2005Ghia et al, , 2008Thorselius et al, 2006;Abramenko et al, 2007;Bomben et al, 2007Bomben et al, , 2009Stamatopoulos et al, 2007;Murray et al, 2008;Messmer et al, 2009;Bilous et al, 2010). In series from Scandinavian countries, IGHV3-21 was the second most frequent gene, being expressed in more than 10% of cases, and was the gene most frequently used in the M configuration, though with a relatively low (2-5%) mutational load (Tobin et al, 2002(Tobin et al, , 2003Thorselius et al, 2006).…”

“…Moreover, IGHV3-21 CLL carrying this short and homologous HCDR3 express IGLV3-21/IGLJ3 light chain genes with homologous CDR3 sequences (Tobin et al, 2002(Tobin et al, , 2003Ghia et al, 2005Ghia et al, , 2008Thorselius et al, 2006;Bomben et al, 2007Bomben et al, , 2009Stamatopoulos et al, 2007;Messmer et al, 2009). This BCR combination is known as 'Subset 2' in the classification of the major BCR stereotypes (Stamatopoulos et al, 2007). An alternative stereotyped BCR carrying the IGHV3-21 heavy chain paired with a IGKV3-20 light chain has been subsequently identified in a minority of IGHV3-21 CLL .…”

“…The IGHV3-23 gene, one of the most frequently used IGHV genes in CLL, is expressed in the majority of cases in a M configuration, and is constantly absent from subsets of stereotyped BCR (Table II) (Stamatopoulos et al, 2007;Bomben et al, 2009;Messmer et al, 2009). Indeed, in the three largest studies published so far that collectively investigated 5,000 CLL cases, none of the confirmed stereotyped CLL subsets included IGHV3-23 sequences (Stamatopoulos et al, 2007;Bomben et al, 2009;Messmer et al, 2009). Given the absence of restricted HCDR3 features in IGHV3-23 rearrangements, a different BCR-mediated mechanism has been postulated for the selection of CLL cells expressing IGHV3-23 genes (Bomben et al, 2010b).…”

Enhanced outgrowth of EBV-transformed chronic lymphocytic leukemia B cells mediated by coculture with macrophage feeder cells

“…2 Furthermore, U-CLL clones frequently display stereotyped B-cell antigen receptors (BCRs) with very similar heavy chain complementarity determining region 3 (HCDR3s) because of common IGHV-D-J rearrangements. [7][8][9][10][11][12] Finally, most U-CLL cells and certain M-CLL cells express autoreactive BCRs. [13][14][15] Collectively, these data indicate that the structure and probably the antigen reactivity of the BCRs of B-CLL cells are intimately linked to the development and evolution of the disease.…”