Nonstochastic pairing of immunoglobulin heavy and light chains expressed by chronic lymphocytic leukemia B cells is predicated on the heavy chain CDR3

Abstract

IntroductionSeveral studies have demonstrated that leukemic B cells of patients with chronic lymphocytic leukemia (CLL) express a restricted immunoglobulin (Ig) heavy chain repertoire and that expression of Ig variable heavy chain (IGHV) genes in CLL is not random. [1][2][3][4][5] One particular IGHV gene, the 51p1 allele of IGHV1-69, generally is expressed with little or no somatic mutation in 10 to 20% of all cases of this disease. 6 Furthermore, CLL B cells that express 51p1 have a preferential use of certain diversity (IGHD) and junctional (IGHJ) gene segments with restricted reading frames (RF) that encode relatively long third complementarity determining regions (CDR3), which have conserved amino acid motifs that are not characteristic of the CDR3s of the Ig expressed by nonneoplastic tonsilar or blood B cells that use 51p1. 3,7,8 The CDR3 is typically the most variable region of the Ig heavy chain and is generally directly involved in binding to conventional antigens. As such, the expression of such conserved Ig with restricted CDR3 argues that the Ig repertoire expressed in this disease is highly selected, suggesting a potential role for antigen in the development and/or progression of CLL.More recently we identified 15 unrelated CLL cases that expressed nearly identical Ig, with Ig heavy and light chain variable regions encoded by 51p1 and IGKV3-20 (A27), respectively. 9 The heavy and light chains of these 15 samples were virtually identical to SMI, a previously characterized CLL that expressed a polyreactive IgM/ autoantibody with low-affinity-binding activity for a variety of self-antigens. 10 The CDR3 regions of both the heavy and light chains together comprise the Ig binding site for antigen. The prevalent use of the 51p1 allele of IGHV1-69 in CLL with little or no somatic mutation allowed us to examine the effect of different Ig heavy chain CDR3 (HCDR3) motifs on Ig light chain pairing in CLL cases that otherwise expressed nearly identical Ig heavy chain variable regions. For this, we examined the IGKV and IGLV gene usage and CDR3 structure of 258 CLL cases that expressed unmutated Ig heavy chains encoded by 51p1 that were identified in a large cohort of 1846 nonselected CLL cases followed by the CLL Research Consortium (CRC). Methods Patient materialBlood was collected from consenting patients who satisfied the diagnostic and immunophenotypic criteria for B-cell CLL 11 and who presented for evaluation at the referral centers of the CRC. Institutional review board approval from each participating institution and informed consent were obtained in all cases, in accordance with the Declaration of Helsinki. Peripheral blood mononuclear cells were isolated by density gradient centrifugation using Ficoll-Hypaque 1077 (Sigma-Aldrich, St Louis, MO), washed twice, and analyzed directly or suspended in fetal calf serum containing 10% dimethylsulfoxide (DMSO; Sigma-Aldrich) for storage in liquid nitrogen. All samples contained more than 90% CLL B cells as Submitted February 8, 2007; accepted June 18, 2007. Pr...

Vλ genes in chronic lymphocytic leukaemia: highly skewed V gene segment usage with similar CDR3 sequences

“…About half of all CLL cases have unmutated immunoglobulin genes and this is associated with poor clinical outcome. One allele of V H 1-69 in CLL is overexpressed in unmutated cases of CLL 3 and the sequence of the CDR3 region, which is important in antigen binding, is identical in a surprisingly high proportion of patients 4,5 again suggesting that antigen-driven processes may be important in leukaemogenesis. There is much less work on the light-chain V gene usage in CLL but there is a biased usage of both k and l light chains.…”

“…4 Mutational analyses of N-RAS, K-RAS, NPM1, FLT3/ITD, FLT3/TKD, CEBPA, KIT, AML1 and MLL/PTD were performed as previously described. 5,6 The correlation of genetic mutations with clinical and laboratory characteristics is summarized in Supplementary Table 1. Among the 272 AML patients recruited, 165 were males and 107 were females with a median age of 52.5 years (range, 19-90).…”

Analyses of Recombinant Stereotypic IGHV3-21–Encoded Antibodies Expressed in Chronic Lymphocytic Leukemia

“…In addition, there are examples in which certain IgH preferentially are expressed with certain Ig L chains (IgL) by CLL cells (3,7). Tobin and colleagues (8), for example, reported that CLL cells that make IgH encoded by one IGHV, namely, IGHV3-21, frequently express l-IgL encoded by IGLV3-21.…”

Overexpression of TCL1 activates the endoplasmic reticulum stress response: a novel mechanism of leukemic progression in mice

“…Malignant CLL cells use a limited repertoire of immunoglobulin heavy and light chain genes to manufacture their BCRs, [1][2][3] and are very responsive to in vitro anti-IgM stimulation. 4,5 Thus, Ag stimulation has been proposed to drive malignant progression of CLL.…”