Restricted Pairing of Immunoglobulin Heavy and Light Chains Expressed by Chronic Lymphocytic Leukemia B Cells Is Predicated on the Heavy Chain CDR3.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2094-2094
Author(s):  
George F. Widhopf ◽  
Craig J. Goldberg ◽  
Traci L. Toy ◽  
Laura Z. Rassenti ◽  
Thomas J. Kipps
Keyword(s):  
Amino Acid ◽  
B Cells ◽  
Heavy Chain ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Sequence Motif ◽  
Amino Acid Motif ◽  
Heavy Chains ◽  
Vh Genes ◽  
Ig Heavy Chain

Abstract Analysis of the immunoglobulin (Ig) heavy chains expressed by the leukemic B cells of patients with chronic lymphocytic leukemia (CLL) has demonstrated that expression of Ig variable heavy chain (VH) genes in CLL is not random. Certain VH genes are more frequently expressed in CLL than in the normal adult B cell repertoire, and some, such as the 51p1 allele of VH1-69, also use of certain diversity (D) and junctional (JH) gene segments that encode third complementarity determining regions (CDR3) with conserved molecular structures. We identified 15 CLL cases among 1,220 examined that express nearly identical Ig heavy and light chains, encoded by 51p1/D3-16/JH3 and VKA27, respectively (Blood, 104:2499, 2004). The highly restricted and virtually identical structure of these B cell receptors strongly suggests selection for Ig in CLL that have a particular binding activity. However, little information is currently available about the light chains expressed by CLL B cells that have 51p1-encoded Ig heavy chains that use other D and JH segments encoding CDR3 that also are repeatedly observed in this disease. We analyzed the VL genes used by 235 CLL cases found to express 51p1-encoded Ig heavy chains among 1,605 CLL patients examined. First, we find restricted light chain isotype expression, as 72% of samples express kappa and 28% express lambda light chains, compared to 65% kappa and 35% lambda within the cohort of all 1,605 CRC CLL samples, and about 60% kappa and 40% lambda expression in normal blood B cells. Nucleotide sequence analysis of the Ig light chain V gene used by these 235 cases revealed that each had greater than 98% homology to an identified germline VK or Vl gene. Additionally, we identified non-stochastic pairing of particular VK and Vl genes with 51p1-encoded heavy chains that have highly-conserved CDR3. Twenty of the 235 cases (8.5%) were found to have Ig light chains encoded by VKO2. Seventeen (85%) of such cases had 51p1-encoded Ig heavy chains that used D2-2 and JH6, 15 of which had nearly identical CDR3 using the amino acid motif DIVVVPAAI. The VKO2-encoded light chains paired with these Ig heavy chains all had nearly identical CDR3 with the amino acid sequence motif QQSYSTPRT. Similarly, seven of the 235 cases (3%) were found to have Ig light chains encoded by Vl3-9. Six (86%) of such cases had 51p1-encoded Ig heavy chains that used D3-3 and JH6, and all had highly conserved heavy chain CDR3 with the amino acid motif YDFWSGYYPNYYYYGMDV. The Vl3-9-encoded light chains paired with these Ig heavy chains all had nearly identical CDR3 with the amino acid sequence motif QVWDSSTXV. Finally, we identified seven additional samples that express a heavy chain using D3-16 and JH3 that have nearly identical CDR3 amino acid sequences GGGYDYIWGSYRPNDAFDI, and also express light chains encoded by VKA27. These seven samples combined with the previous 15 represent all of the 51p1-encoded heavy chains that utilize D3-16 and JH3, as well as 52% (22 of 42) of all 51p1-encoded CLL samples that express VKA27-encoded light chains. These studies reveal for the first time that CLL cases using the same unmutated Ig heavy chain have non-stochastic pairing with disparate Ig light chains that is predicated upon the Ig heavy chain CDR3 structure. Because the CDR3 typically forms a major part of antibody binding site(s) for antigen, these data provide compelling evidence for antigen selection of the antibodies expressed in CLL.

Stereotypic IGHV3-21/IGLV3-21 Antibodies Expressed in High-Risk Chronic Lymphocytic Leukemia Bind Peptostreptococcus Magnus Protein L.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 740-740
Author(s):  
Emanuela M. Ghia ◽  
Laura Z. Rassenti ◽  
George F. Widhopf ◽  
Gregg J. Silverman ◽  
Donna S. Neuberg ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chronic Lymphocytic Leukemia ◽  
Specific Binding ◽  
Recombinant Antibodies ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Amino Acid Motif ◽  
Protein L ◽  
Heavy Chains ◽  
Peptostreptococcus Magnus

Abstract We examined a large cohort (N=2,457) of chronic lymphocytic leukemia (CLL) patients evaluated by the CLL Research Consortium (CRC) and found 63 (2.6%) used IGHV3-21. Comparing the Ig heavy chain third complementarity determining region (HCDR3) of the IGHV3-21 cases: 25/63 cases (39.7%) had a conserved amino acid motif (motif 1: DANGMDV) in the otherwise highly variable Ig HCDR3, as described by Tobin et al. Blood 2003. All but one of these Ig heavy chains (IgH) were paired with a lambda light chain encoded by IGLV3-21. In addition, we found that 3/63 cases (4.8%) had a previously unrecognized conserved HCDR3 amino acid motif (motif 2: DPSFYSSSWTLFDY). In contrast, these IgH invariably were paired with kappa immunoglobulin light chains (IgL) encoded by IGKV3-20. Similarly to that noted for CLL cases that use IgH encoded by unmutated IGHV1-69 (Widhopf et al. Blood Epub First Edition 2007), the pairing of IgH encoded by IGHV3-21 with IgL appears governed by the HCDR3. The non-stochastic pairing of IgH with IgL argues strongly that antigen plays a role in selecting the Ig expressed in CLL. To examine for the antigen(s) recognized by the most common Ig encoded by IGHV3-21, we isolated IgH and IgL genes expressed by IGHV3-21/IGLV3-21 CLL cases and generated recombinant antibodies, which we examined for binding to antigen(s) present on microarray of self or environmental antigens. We found that Ig encoded by IGHV3-21/IGLV3-21 had apparent specific binding for protein L, a multi-domain cell-wall protein isolated from Peptostreptococcus magnus, a Gram-positive commensal bacteria that comprise a large portion of the human bacterial gut flora. Prior studies identified that protein L is a superantigen capable of binding human Ig kappa light chains encoded by IGKV genes of the I, III, and IV subgroups, but not human Ig lambda light chains. The specific binding of IGHV3-21/IGLV3-21 to protein L suggested that protein L might play a role in the development of CLL cells that express such Ig. To test this hypothesis, we examined the capacity of various recombinant antibodies to bind protein L by ELISA. We found that lambda IgL encoded by IGLV3-21 could bind to protein L with similar activity, independent of whether this lambda IgL paired with the native IgH, IgH encoded by IGHV3-21 lacking the DANGMDV HCDR3 motif, or even irrelevant IgH encoded by IGHV4-39 that are not found paired with IGLV3-21 in the Ig expressed in CLL. Moreover, Ig formed by pairing IgH encoded by IGHV3-21 that has the DANGMDV HCDR3 motif with an IgL encoded by an IGLV that was irrelevant to IGLV3-21 did not bind protein L. These results reveal a previously unrecognized capacity of human IgL encoded by IGLV3-21 to bind the protein L superantigen of Peptostreptococcus magnus, a bacteria commonly found in the human gastrointestinal tract. However, because the binding of IGLV3-21 does not depend upon the non-stochaistic pairing of IgH and IgL observed in CLL, we reason that the capacity of IGLV3-21 to bind protein L cannot account for the selected Ig repertoire expressed in CLL, suggesting that it actually does not play a role in CLL leukemogenesis. This finding suggests that caution should be exercised when defining an antigen that is found capable of binding the restricted Ig expressed in CLL as the driving factor responsible for leukemogenesis.

Study of VH3-21 in a Large Cohort of Chronic Lymphocytic Leukemia Patients Reveals Evidence for Antigen Selection and Confirms Its Predictive Value for Early Disease Progression.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2774-2774
Author(s):  
Emanuela M. Ghia ◽  
Laura Z. Rassenti ◽  
George F. Widhopf ◽  
Donna S. Neuberg ◽  
Michael J. Keating ◽  
...  
Keyword(s):  
United States ◽  
Amino Acid ◽  
Chronic Lymphocytic Leukemia ◽  
Disease Progression ◽  
Heavy Chain ◽  
The United States ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Early Disease ◽  
Ig Heavy Chain

Abstract The use frequency of the immunoglobulin (Ig) heavy chain variable region gene (VH) 3–21 in chronic lymphocytic leukemia (CLL) varies among studies on various cohorts of European patients, ranging from 0.9%–10%. Such variation could be due to geographic/population differences and/or sample-size limitations. We examined a large cohort (N=2,190) of CLL patients evaluated in the United States by the CLL Research Consortium (CRC) and found 56 (2.6%) used IgVH3-21. Thirty-five of the 56 cases (63%) expressed Ig light chains, whereas only 821 (38%) of the 2,134 cases that used IgVH other than IgVH3-21 used light chains, a difference that was highly significant (P < 0.001). Cases that used IgVH3-21 and light chains had significantly fewer amino acid residues in Ig heavy chain third complementarity determining region (CDR3) (m = 11.5 ± 5.3, S.D.) than did VH3-21 cases with light chains (m = 18.4 ± 4.8) (P<0.001). Twenty-eight of the 56 cases (50%) used unmutated IgVH3-21, defined as having >98% homology to germline VH3-21. Twenty (43%) or 18 (38%) of the 47 cases examined by flow cytometry expressed ZAP-70 or high-level CD38, respectively. Although there was frequent concordant expression of ZAP-70 and/or CD38 with unmutated IgVH3-21, such associations were not absolute, as had been noted for CLL cases that did not use IgVH3-21. Thirty-two percent (18/56) of the cases had a previously described common amino-acid motif (ARDANGMDV) in the otherwise highly variable Ig heavy-chain CDR3. Seventeen (94%) of such cases used light chains typically encoded by V3-21/J3. In addition, we identified a novel amino-acid consensus motif (DPSFYSSSWTLFDY) in the Ig heavy chain CDR3 for 3 of the 56 cases (5.4%). We examined the time from diagnosis to initiation of therapy as per established NCI-Working Group guidelines in 40 patients for whom complete clinical data were available. With a median follow-up of 4.2 years from the date of diagnosis, 25 of the 40 patients had received therapy at the time of this analysis. The median time to treatment (TTT) for all 40 patients was 3.5 years, which was significantly shorter than the median TTT of 6.6 years noted for a previously-described CRC cohort of 307 patients that were not selected for use of IgVH3-21 (NEJM2004; 351: 893–901) (P<0.001). The median TTT of 19 patients that used unmutated IgVH3-21 in this subset (3.0 years) appeared shorter than that noted for the 21 patients that had mutated IgVH3-21 (5.4 years), but this difference did not reach statistical significance. We conclude that a small proportion of patients studied in the United States by the CRC use IgVH3-21, which encodes Ig heavy chains that frequently have canonical motifs in the CDR3 and that typically are paired with certain Ig light chains, providing strong evidence for Ig selection by antigen(s). Finally, patients with IgVH3-21-expressing CLL have a higher risk for early disease progression than do patients with CLL not selected for use of IgVH3-21.

Evidence for the Significant Role of Immunoglobulin Light Chains in Antigen Recognition and Selection in Chronic Lymphocytic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 780-780
Author(s):  
Anastasia Hadzidimitriou ◽  
Nikos Darzentas ◽  
Fiona Murray ◽  
Tanja Smilevska ◽  
Eleni Arvaniti ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chronic Lymphocytic Leukemia ◽  
Heavy Chain ◽  
Light Chain ◽  
Antigen Recognition ◽  
Lymphocytic Leukemia ◽  
Light Chains ◽  
Light Chain Gene ◽  
Heavy Chains ◽  
Gene Usage

Abstract The chronic lymphocytic leukemia (CLL) immunoglobulin (IG) heavy chain repertoire is known to display biased immunoglobulin variable heavy-chain (IGHV) gene usage, remarkable complementarity determining region 3 (HCDR3) stereotypy as well as distinctive somatic hypermutation (SHM) patterns, at least for subsets of cases. Our aim in the present study was to similarly investigate the IG light chain (LC) genes in terms of mutation frequency and targeting and CDR3 stereotypy to elucidate if the LC may play a significant complementary role in antigen recognition in CLL. We thus examined SHM patterns and secondary rearrangements of the IG LC gene loci in a total of 612 IGKV-J and 279 IGLV-J rearrangements from 725 patients with CLL. Firstly, we observed a highly restricted light chain gene usage in the vast majority of CLL cases with stereotyped HCDR3s. In particular, stereotyped IGHV3-21 CLL cases were characterized by a strikingly biased expression of lambda light chains utilizing the IGLV3-21 gene (36/37 cases of subset#2), whereas all 15 subset #4 cases with stereotyped IGHV4-34 IGs carried an IGKV2-30 rearrangement. In addition, subset-biased light chain CDR3 motifs were identified in groups of sequences utilizing the same IGKV or IGLV gene. For example, all 30 IGKV1-39/1D-39 light chains of subset#1 (using stereotyped IGHV1/5/7 genes) carried notably long KCDR3s (10–11 amino acids) generated by significant N region addition and characterized by the frequent introduction of a junctional proline (26/30 cases). Important differences regarding mutational load were observed in groups of sequences utilizing the same IGKV or IGLV gene and/or belonging to subsets with stereotyped B cell receptors (BCRs). In fact, significant differences were observed with regard to mutational status among groups of sequences utilizing different alleles of certain IGK/LV genes (specifically the IGKV1-5, IGLV1-51 and IGLV3-21 genes). At cohort level, the SHM patterns were typical of a canonical SHM process. A clustering of R mutations in KCDR1 was evident for all IGKV subgroups with the notable exception of the IGKV2 subgroup, which exhibited preferential targeting to the KCDR2, especially in IGKV2-30 rearrangements of cases with stereotyped IGHV4-34/IGKV2-30 BCRs (subset#4). Recurrent amino acid changes at certain positions across the entire IGKV/IGLV sequence were observed at a high frequency (27–67% of cases) in a number of stereotyped subsets, especially those expressing the IGHV3-21/IGLV3-21 BCR (subset #2) and the IGHV4-34/IGKV2-30 BCR (subset #4). Comparison with CLL LC sequences carrying heterogeneous K/LCDR3s or non-CLL LC sequences revealed that these distinct amino acid changes are greatly under-represented in such groups and appear therefore to be “subset-biased”. Finally, a significant proportion of CLL cases (63 cases; 26 kappa- and 37 lambda-expressing) with monotypic LC expression were found to carry multiple potentially functional LC rearrangements. Of note, nineteen of these 63 cases (30%) belonged to subsets with stereotyped BCRs. This finding alludes to the possibility of secondary rearrangements most likely occurring in the context of (auto)antigen-driven receptor editing, particularly in the case of stereotyped subsets. In conclusion, SHM targeting in CLL LCs appears to be just as precise and, most likely, functionally driven as in heavy chains. Secondary LC gene rearrangements and subset-biased mutations in CLL LC genes are strong indications that LCs are crucial in shaping the specificity of leukemic BCRs, in association with defined heavy chains. Therefore, CLL is characterized not only by stereotyped HCDR3 and heavy chains but, rather, by stereotyped BCRs involving both chains, which create distinctive antigen binding grooves.

scholarly journals Loss of an individual idiotype on chemical modification. A strategy for assigning idiotypic determinants.

1981 ◽  
Vol 153 (5) ◽  
pp. 1275-1285 ◽  
Author(s):  
J Dickerman ◽  
B Clevinger ◽  
B Friedenson
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Chemical Modification ◽  
Heavy Chain ◽  
Light Chains ◽  
Heavy Chains ◽  
Myeloma Proteins ◽  
Low Levels ◽  
The Individual ◽  
Complementary Strategy

Two dextran-binding myeloma proteins, J558 and Hdex 24, which possess the same individual idiotype (IdI) were diazotized to low levels (1-3.3 groups per subunit) with 1-[14C]-p-aminobenzoate. Both proteins lost the IdI idiotype under these conditions with most of the label incorporated on the heavy chains of each protein. When the diazotization ws carried out in the presence of the hapten 1-O-methyl-alpha-D-glucopyranoside the loss of idiotypic reactivity could be prevented for J558 but not for Hdex 24. Under these conditions most of the label was incorporated on the light chains of J558, but on the heavy chains of Hdex 24. For J558, these results show that a major determinant of the individual idiotype is within the hypervariable positions of the heavy chain. For Hdex 24 the determinant being modified is on the heavy chain but not involved in hapten binding. These results are consistent with previous work showing that J558 and Hdex 24 differ in amino acid sequence in the D and the J segments of the heavy chain and offer an alternative and complementary strategy for assigning idiotypic determinants.

scholarly journals The amino acid sequences of the Fd fragments of two human γ 1 heavy chains

1970 ◽  
Vol 117 (4) ◽  
pp. 641-660 ◽  
Author(s):  
E. M. Press ◽  
N. M. Hogg
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Heavy Chain ◽  
Variable Region ◽  
Amino Acid Sequences ◽  
Light Chains ◽  
Aspartic Acid Residue ◽  
Variable Regions ◽  
Heavy Chain Variable Region ◽  
Heavy Chains

The amino acid sequences of the Fd fragments of two human pathological immunoglobulins of the immunoglobulin G1 class are reported. Comparison of the two sequences shows that the heavy-chain variable regions are similar in length to those of the light chains. The existence of heavy chain variable region subgroups is also deduced, from a comparison of these two sequences with those of another γ 1 chain, Eu, a μ chain, Ou, and the partial sequence of a fourth γ 1 chain, Ste. Carbohydrate has been found to be linked to an aspartic acid residue in the variable region of one of the γ 1 chains, Cor.

scholarly journals Immunoglobulin phenotype on B cells correlates with clinical stage of chronic lymphocytic leukemia

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 256-263
Author(s):  
FS Ligler ◽  
JR Kettman ◽  
RG Smith ◽  
EP Frenkel
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Heavy Chain ◽  
Clinical Stage ◽  
Lymphocytic Leukemia ◽  
Light Chain Type ◽  
Immature B Cells ◽  
Advanced Stages ◽  
Ig Heavy Chain ◽  
Chain Type

The present study examines the relative amounts of surface immunoglobulin (Ig) on lymphocytes obtained from 64 patients with chronic lymphocytic leukemia (CLL) and correlates these findings with the clinical stage of disease. Since the maturing B cell first expresses surface IgM, followed by IgD, and subsequently by IgG, IgA, or IgE, the surface Ig phenotype can be used as a marker of differentiation. Surface Ig was analyzed using the fluorescence- activated cell sorter under carefully controlled conditions. The cells from all patients with CLL were monoclonal with respect to light chain type. Those patients with IgM as the brightest heavy chain class (suggesting relatively immature B cells) had clinically advanced stages of CLL, whereas those with a predominance of IgG (suggesting more mature cells) have a lesser stage of CLL. Thus, the predominant Ig heavy chain class appears to correlate with clinical stage of CLL and provides a clue to the potential aggressiveness of the tumor.

Studies on the amino acid sequence of heavy chains from rabbit immunoglobulin G

1966 ◽  
Vol 166 (1003) ◽  
pp. 159-175 ◽  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Heavy Chain ◽  
Immunoglobulin G ◽  
Light Chains ◽  
Antibody Specificity ◽  
Sequence Heterogeneity ◽  
Specific Antibodies ◽  
Heavy Chains ◽  
Insight Into

It is now generally agreed that the four-chain subunit structure of Immunoglobulins which was first proposed by Porter (1962), accurately represents the gross structure of immunoglobulin G (IgG) and specific antibodies (Fleischman, Porter & Press 1963; Edelman & Gally 1964; Marler, Nelson & Tanford 1964; Nelson et al . 1965). However, an understanding of the structural basis of antibody specificity requires greater insight into the amino acid sequence of the polypeptide chain components of specific antibodies. Isolated light chains from specific antibodies and inert IgG, show a considerable degree of electrophoretic heterogeneity (Edelman & Gally 1964; Cohen & Porter 1964; Poulik 1964). Tryptic peptide maps of light chains (Nelson et al . 1965) have suggested that this heterogeneity may be accounted for by differences in amino acid sequence. This view has received considerable support from the observation that Bence-Jones proteins, which may be regarded as light chains, vary significantly in amino acid sequence (Hilschman & Craig 1965; Milstein 1966; Titani, Whitley & Putman 1966). A similar but less well-defined sequence heterogeneity has been suggested to exist in the heavy chains of specific antibodies (Feinstein 1964). However, the Fc fragment of the heavy chains has been thought to possess a regular amino acid sequence which may be similar, if not identical, among all specific antibodies (Porter 1959; Nelson et al . 1965). This paper summarizes the results of studies on the amino acid sequence of heavy chains and that portion of heavy chain, Fc fragment, which is obtained on treatment of rabbit IgG with papain (Porter 1959). These studies were designed to determine how much of the amino acid sequence of heavy chain could be accounted for by a unique, regular amino acid sequence which was common to most, if not all, IgG antibodies. In addition, attempts were made to locate regions of heavy chains which varied in amino acid sequence. Although structural variants appear to occur among the heavy chains found in non-specific IgG, it would be desirable to know what portion of the heavy chain sequence is invariant among all antibodies. If antibody specificity results from sequence heterogeneity in light and heavy chains, then knowledge of the variant and invariant portions of these chains may provide insight into the nature of specific binding sites in anti-­bodies.

scholarly journals Lack of Allelic Exclusion in B Cell Chronic Lymphocytic Leukemia

1997 ◽  
Vol 185 (8) ◽  
pp. 1435-1446 ◽  
Author(s):  
Laura Z. Rassenti ◽  
Thomas J. Kipps
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Heavy Chain ◽  
Protein A ◽  
Lymphocytic Leukemia ◽  
Allelic Exclusion ◽  
Staphylococcal Protein A ◽  
Vh Genes ◽  
Ig Heavy Chain ◽  
Cell Chronic Lymphocytic Leukemia

We determined the immunoglobulin (Ig) VH subgroup expressed by the leukemia cells of 108 patients with B cell chronic lymphocytic leukemia (CLL). Surprisingly, we found that six samples (5%) each expressed Ig of more than one VH subgroup. Southern blot analysis demonstrated that these samples each had rearrangements involving both Ig heavy chain alleles. Nucleic acid sequence analyses of the Ig cDNA revealed each to express two functional Ig VH genes: VH3-33 and VH4-39; VH3-7 and VH4-39; VH3-23 and VH4-61; VH2-70 and VH3-30.3; or VH3-30 and VH4-b (DP67). One sample expressed three Ig VH genes: VH2-70, VH3-7, and VH4-59. Despite having more than one Ig heavy chain transcript, each sample was found to express only one functional Ig light chain. From the primary sequence, we deduced that the Ig of some of these CLL samples should react with Lc1, a monoclonal antibody (mAb) reactive with a supratypic cross-reactive idiotype present on Ig encoded by a subgroup of Ig VH4 genes (namely, VH4-39, VH4-b [DP-67], VH4-59, or VH4-61), and B6, an mAb that reacts with Ig encoded by certain Ig VH3 genes (namely, VH3-23, VH3-30, or VH3-30.3), and/or modified staphylococcal protein A (SpA), a 45-kilodalton bacterial “superantigen” that reacts with most Ig of the VH3 subgroup. Flow cytometric analyses revealed that such samples did in fact react with Lc1 and B6 and/or SpA, but not with control mAbs of irrelevant specificity. This study demonstrates that a subset of CLL patients have leukemic B cells that express more than one functional Ig heavy chain.

scholarly journals The ultrastructural localization of immunoglobulin in chronic lymphocytic lymphoma cells: changes in light and heavy chain distribution induced by mitogen stimulation

Blood ◽  
1983 ◽  
Vol 61 (3) ◽  
pp. 511-519 ◽  
Author(s):  
DG Newell ◽  
AH Harris ◽  
JL Smith
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Heavy Chain ◽  
Ultrastructural Localization ◽  
Lymphocytic Leukemia ◽  
Pokeweed Mitogen ◽  
Light Chains ◽  
Immunoperoxidase Technique ◽  
Mitogen Stimulation ◽  
Heavy Chains

Abstract The distribution of light and heavy immunoglobulin chains in chronic lymphocytic leukemia (CLL) cells has been investigated at the ultrastructural level using an immunoperoxidase technique. Light chains were localized in the lumens of the perinuclear space and rough endoplasmic reticulum, while staining for heavy chains was weak or negative and generally confined to the membranes of the rough endoplasmic reticulum. This pattern is consistent with immunoglobulin biosynthetic studies on CLL cells in which light chains are synthesized in excess over heavy chains and secreted as the exclusive immunoglobulin product. The pokeweed mitogen stimulation of two populations of CLL cells for 6 days resulted in a balanced synthesis and secretion of light and heavy chains that was reflected in concomitant change in light and heavy chain distribution and intensity of staining using the immunoperoxidase technique.

scholarly journals Association of 4F2hc with light chains LAT1, LAT2 or y+LAT2 requires different domains

2001 ◽  
Vol 355 (3) ◽  
pp. 725-731 ◽  
Author(s):  
Angelika BRÖER ◽  
Björn FRIEDRICH ◽  
Carsten A. WAGNER ◽  
Sophie FILLON ◽  
Vadivel GANAPATHY ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Amino Acid ◽  
Heavy Chain ◽  
Membrane Surface ◽  
Transmembrane Helix ◽  
Surface Expression ◽  
Light Chains ◽  
Amino Acid Transporters ◽  
Slight Reduction ◽  
Heavy Chains

Heterodimeric amino acid transporters are comprised of a type-II membrane protein named the heavy chain (4F2hc or rBAT) that may associate with a number of different polytopic membrane proteins, called light chains. It is thought that the heavy chain is mainly involved in the trafficking of the complex to the plasma membrane, whereas the transport process itself is catalysed by the light chain. The 4F2heavy chain (4F2hc) associates with at least six different light chains to induce distinct amino acid-transport activites. To test if the light chains are specifically recognized and to identify domains involved in the recognition of light chains, C-terminally truncated mutants of 4F2hc were constructed and co-expressed with the light chains LAT1, LAT2 and y+LAT2. The truncated isoform T1, comprised of only 133 amino acids that form the cytosolic N-terminus and the transmembrane helix, displayed only a slight reduction in its ability to promote LAT1 expression at the membrane surface compared with the 529 amino acid wild-type 4F2hc protein. Co-expression of increasingly larger 4F2hc mutants caused a delayed translocation of LAT1. In contrast to the weak effects of 4F2hc truncations on LAT1 expression, surface expression of LAT2 and y+LAT2 was almost completely lost with all truncated heavy chains. Co-expression of LAT1 together with the other light chains did not result in displacement of LAT2 and y+LAT2. The results suggest that extracellular domains of the heavy chain are responsible mainly for recognition of light chains other than LAT1 and that the extracellular domain ensures proper translocation to the plasma membrane.

Sign in / Sign up

Export Citation Format

Share Document