AIDS primary central nervous system lymphoma: molecular analysis of the expressed VH genes and possible implications for lymphomagenesis

AIDS-associated primary central nervous system lymphomas are late events that have an extremely poor prognosis. Despite different hypotheses, the brain localization of these B cell lymphomas remains an enigma. To better define the cell origin of the lymphomas and the possible role of the B cell receptor (BCR) in the brain localization and/or in the oncogenic transformation, we analyzed the V region genes of the Ig heavy chain expressed by lymphoma cells in five randomly selected patients. After amplifying the rearranged VHDJH DNA by PCR, cloning, and sequencing of the amplified products, we observed that: 1) of the five lymphomas analyzed, four were clearly monoclonal; 2) there was no preferential use of one peculiar VH family or one peculiar segment of gene; 3) the mutation analysis showed that an Ag-driven process occurred in at least two cases, probably before the oncogenic event; and 4) there was no intraclonal variability, suggesting that the hypermutation mechanism is no longer efficient in these lymphoma B cells. Taken together, our results suggest that distinct Ags could be recognized by the BCR of the lymphoma cells in different patients and that, if the Ags are responsible for the brain localization of these B cells bearing mutated BCR, other factors must be involved in B cell transformations in primary central nervous system lymphoma.

Terminal Deoxynucleotidyl Transferase Deficiency Reduces the Incidence of Autoimmune Nephritis in (New Zealand Black × New Zealand White)F1 Mice

Terminal deoxynucleotidyl transferase (TdT) enzyme activity in lymphocytes generates diversity in the Ag receptor repertoires by adding template-independent N nucleotides and disrupting homology-directed rearrangements. The importance of this diversity in vivo and the significance of the suppression of TdT during fetal life remain uncertain. Previous studies have shown that in TdT knockout mice (TdT°) 1) the T cell repertoire is less peptide oriented; and 2) natural autoantibody, particularly anti-DNA autoantibodies, are less polyreactive, and their mean affinities are reduced. Consequently, the suppression of TdT during early T/B cell ontogeny may participate in controlling autoimmunity. To study the impact of TdT suppression in autoimmune-prone mice, we introduced the TdT null mutation into the (NZB × NZW)F1 (B/W) mouse strain. We show that TdT deficiency significantly reduces the incidence of autoimmune nephritis and prolongs survival compared with those in control mice. Surprisingly, the long-term survivor TdT° mice produced amounts of anti-ADN and anti-histone autoantibodies similar to those of their TdT+ littermates. However, these TdT° mice showed no evidence of renal inflammation, and the immune deposits were restricted to the mesangium, whereas basal membrane deposits were clearly correlated with overt renal disease. The present study supports the idea that the absence of TdT enzyme activity in lymphocytes protects mice against autoimmunity and could offer a therapeutic approach to autoimmune diseases. Moreover, our results may help to unravel the mechanisms of lupus nephritis.

Terminal deoxynucleotidyl transferase deficiency reduces the incidence of autoimmune nephritis in (New Zealand Black x New Zealand White)F1 mice

Terminal deoxynucleotidyl transferase (TdT) enzyme activity in lymphocytes generates diversity in the Ag receptor repertoires by adding template-independent N nucleotides and disrupting homology-directed rearrangements. The importance of this diversity in vivo and the significance of the suppression of TdT during fetal life remain uncertain. Previous studies have shown that in TdT knockout mice (TdT(0)) 1) the T cell repertoire is less peptide oriented; and 2) natural autoantibody, particularly anti-DNA autoantibodies, are less polyreactive, and their mean affinities are reduced. Consequently, the suppression of TdT during early T/B cell ontogeny may participate in controlling autoimmunity. To study the impact of TdT suppression in autoimmune-prone mice, we introduced the TdT null mutation into the (NZB x NZW)F1 (B/W) mouse strain. We show that TdT deficiency significantly reduces the incidence of autoimmune nephritis and prolongs survival compared with those in control mice. Surprisingly, the long-term survivor TdT(0) mice produced amounts of anti-ADN and anti-histone autoantibodies similar to those of their TdT+ littermates. However, these TdT(0) mice showed no evidence of renal inflammation, and the immune deposits were restricted to the mesangium, whereas basal membrane deposits were clearly correlated with overt renal disease. The present study supports the idea that the absence of TdT enzyme activity in lymphocytes protects mice against autoimmunity and could offer a therapeutic approach to autoimmune diseases. Moreover, our results may help to unravel the mechanisms of lupus nephritis.

[Soluble tumor necrosis factor receptors in patients with systemic lupus erythematosus]

OBJECTIVE

To study the variations of type II soluble receptors for tumor necrosis factor (sR-TNF) in patients with systemic lupus erythematosus and investigate their use in the clinical setting.

PATIENTS AND METHODS

Twenty-six patients with systemic lupus were followed for a mean 3 years. sR-TNF and other immunological parameters (C reactive protein, anti-DNA antibodies, C3 and C4 complement fractions, soluble receptors for interleukin 2) were measured in sera at different points of the disease course. The systemic lupus activity measure (SLAM) was determined at each point, and confronted with the biology results. The study was cross sectional for the group and longitudinal for the patients.

RESULTS

sR-TNF was the immunological parameter which correlated best with SLAM. It also correlated with sedimentation rate, C reactive protein, thrombopenia, anemia, creatinine level, anti-DNA antibodies and sR-IL2. The longitudinal study pointed out however that this finding is not consistent for each patient.

CONCLUSION

A rise in sR-TNF related to systemic lupus activity but is of limited practical interest for individual patient follow-up.

Autoantibodies in mice lacking terminal deoxynucleotidyl transferase: evidence for a role of N region addition in the polyreactivity and in the affinities of anti-DNA antibodies

The generation of terminal deoxynucleotidyl transferase knockout mice (TdT0) has demonstrated that TdT is the only major activity involved in N region addition. This enzyme generates diversity by adding random nucleotides at the V-D-J junctions and by disrupting the formation of repetitive "homology-directed" junctions. Several studies have demonstrated that the Ig heavy chain third complementarity-determining region (H-CDR3) and the N region play a critical role: 1) in distinguishing between polyreactive and monospecific combining sites in natural and Ag-induced Abs; and 2) in the specificity and polyreactivity of natural autoantibodies (autoAbs) and in particular of anti-DNA Abs. To examine the impact of the lack of TdT on the natural autoAb repertoire in adult mice, we have stimulated TdT0 and TdT+ littermates with LPS. Serum studies demonstrate that TdT is not critical for the generation of B cells expressing autoAbs including anti-DNA Abs and rheumatoid factors. However, the generation of a large collection of hybridomas indicates that the frequencies of these cells are reduced in TdT0 mice mainly due to a lower incidence of polyreactivity; also, the lack of N region diversity seems to negatively affect the affinity of anti-DNA Abs. The physiologic relevance of these data is discussed.

Autoantibodies in mice lacking terminal deoxynucleotidyl transferase: evidence for a role of N region addition in the polyreactivity and in the affinities of anti-DNA antibodies

The generation of terminal deoxynucleotidyl transferase knockout mice (TdT0) has demonstrated that TdT is the only major activity involved in N region addition. This enzyme generates diversity by adding random nucleotides at the V-D-J junctions and by disrupting the formation of repetitive "homology-directed" junctions. Several studies have demonstrated that the Ig heavy chain third complementarity-determining region (H-CDR3) and the N region play a critical role: 1) in distinguishing between polyreactive and monospecific combining sites in natural and Ag-induced Abs; and 2) in the specificity and polyreactivity of natural autoantibodies (autoAbs) and in particular of anti-DNA Abs. To examine the impact of the lack of TdT on the natural autoAb repertoire in adult mice, we have stimulated TdT0 and TdT+ littermates with LPS. Serum studies demonstrate that TdT is not critical for the generation of B cells expressing autoAbs including anti-DNA Abs and rheumatoid factors. However, the generation of a large collection of hybridomas indicates that the frequencies of these cells are reduced in TdT0 mice mainly due to a lower incidence of polyreactivity; also, the lack of N region diversity seems to negatively affect the affinity of anti-DNA Abs. The physiologic relevance of these data is discussed.

The significance of shed membrane particles during programmed cell death in vitro, and in vivo, in HIV-1 infection

The plasma membrane remodeling, including the early transverse redistribution of phosphatidylserine, is a general feature occurring in cells in which a death program has been induced. In most cases, studies of this kind have focused mainly on cells. In this study, we report a clear correlation between the degree of apoptosis induced by a variety of agents in several types of cultured cells and the amount of shed membrane microparticles captured in the corresponding supernatants by insolubilized annexin V, a protein showing a strong affinity for phosphatidylserine. Such particles carry membrane antigens specific of the cells they stem from, and through which capture is also feasible. Homologous circulating microparticles were captured in peripheral blood from individuals with HIV-1 infection. A substantial proportion bore CD4 antigen. In some cases, CD4+ particles could be detected even in the absence of circulating CD4+ T cells, testifying to the presence of such resident cells in lymphoid tissues. These results suggest that shed membrane particles are one of the hallmarks of programmed cell death, of particular interest when the corresponding cells are hardly accessible.

[Lipomatosis induced by corticosteroid therapy]

Steroid-induced lipomatosis usually presents as a localized hypertrophy of the adipose tissue and seems more common than previously thought. Most patients develop this phenomenon after prolonged administration of moderate to high doses of oral corticosteroids. The localizations are numerous and determine the clinical presentation. Often asymptomatic, they can also be revealed by worrying symptoms usually due to a compressive syndrome. The most frequently reported localizations (spinal epidural, retro-orbital, mediastinal) are also the most clinically apparent. The cessation or reduction of steroid therapy, when medically possible, inconsistently results in the decrease or disappearance of the lipomatosis deposits. Computerized tomography or magnetic resonance imaging are the most helpful diagnostic means. Interestingly, these lipomatoses have rarely been reported in patients with Cushing disease. Their pathophysiology remains poorly elucidated and may imply an inhibition of the brown adipose tissue lipolysis.

Albumin-impregnated polyester vascular prosthesis for abdominal aortic surgery: an improvement?

AIM

To compare the peroperative blood loss and the postoperative systemic inflammatory reaction in patients receiving either a Vasculour II Albumin pre-impregnated prosthesis (VA group, n = 32) or a preclotted Vasculour II prosthesis (V group, n = 33) for elective surgery of the abdominal aorta.

SETTING

University Hospital.

DESIGN

Prospective, randomised study.

METHODS

Peroperative blood loss was measured over two different periods: Phase I from the beginning of the operation to the completion of the proximal anastomosis, when blood loss cannot be related to the model of prosthesis implanted and phase II after the completion of the proximal anastomosis to the end of the operation. Postoperative blood loss was evaluated by the determination of the retroperitoneal drainage volume over a period of 2 days immediately following the operation. The presence of periprosthetic fluid was measured with echography at days 4, 9, 30 and 60. The postoperative systemic inflammatory reaction was evaluated by measuring the sedimentation rate and the C reactive protein levels daily from day 1 to day 9, and at days 14, 21, 28, 45, and 60, and by measuring the body temperature daily from day 1 to day 9.

RESULTS

No significant differences of peroperative blood loss were observed. The same proportion of patients (35%) in both groups received homologous transfusion. The mean number of units of homologous blood transfused per patient was respectively 0.77 and 0.91 for the VA and the V group. The retroperitoneal drainage volume and the percentage of patients with periprosthetic fluid did not differ significantly. No significant differences in systemic postoperative inflammatory reaction were observed.

CONCLUSION

There were no benefits in using albumin-impregnated prosthesis as opposed to preclotted prosthesis in terms of peroperative and postoperative blood loss, or by looking at the incidence of homologous blood transfusion. However, the glutaraldehyde cross-linked albumin did not induce any systemic inflammatory reaction.

Detection of bilayer phospholipid-binding antibodies using flow cytometry

Antiphospholipid antibodies (APL) are usually detected using solid-phase immunoassays, where cardiolipin is the most common capture antigen. Phosholipids are believed to adopt a monolayer organization when coated onto polystyrene after evaporation of the solvent. However, bilayer phospholipids are probably those evidenced as microparticles or cell fragments circulating in vivo under various pathological circumstances. The surface density of monolayer phospholipids on polystyrene is six times lower than that of bilayer phospholipids. In order to assess the influence of phospholipid organization on the detection of APL, we prepared glass microspheres coated with bilayer phospholipids (cardiolipin, phosphatidylcholine, cholesterol). Such lipospheres enabled us to study the binding of antibodies in 1:100 diluted plasma samples from patients with anticardiolipin antibodies of IgG isotype previously diagnosed by ELISA. Among the 39 plasma samples analysed by flow cytometry, 17 showed positive IgG binding to lipospheres. Only four additional samples became positive when adding 20 micrograms/ml apolipoprotein H. The specificity of the binding was demonstrated by complete reversibility with 1.4 microM annexin V and with a large excess of liposomes of the same composition. The absence of correlation between liposphere and ELISA results suggests that different subgroups of antibodies are detected depending on the method. The detection of APL using bilayer phospholipids is an original assay and may represent a more physiopathological approach to the specificity of APL.

[Treatment of lupus glomerulonephritis with intravenous cyclophosphamide]

The treatment of severe lupus nephritis remains problematic. We have analysed retrospectively 17 patients with corticoresistant lupus nephritis treated with pulse cyclophosphamide. Single monthly doses (500 mg/m2) were given by intravenous infusion with a mean of 10.4 infusions per patient (3 to 18). A comparison of parameters at entry and at the end of the treatment revealed an improvement in proteinuria (4.8 vs 1.9 g/24 h; p < 0.013) whereas mean serum creatinine level and SLAM (Systemic Lupus Activity Measure) remained stable. The results were identical at follow up (mean: 14.5 months). Most of the therapeutic effect was achieved as soon as the 6th pulse. Further treatment was beneficial for four patients only. None of the studied parameters (serum creatinine level, renal biopsy, SLAM) was predictive of a response to an extended course of pulse cyclophosphamide. The infusions were definitively stopped in one patient and delayed in two others because of serious adverse effects. The data indicate that, in mean term, monthly intravenous cyclophosphamide was associated with a substantial amelioration of 24 hours urinary protein level. An amelioration of the renal function was however, uncommon.

Heavy chain variable region, light chain variable region, and heavy chain CDR3 influences on the mono- and polyreactivity and on the affinity of human monoclonal rheumatoid factors

Monoreactive high affinity pathologic autoantibodies were supposed previously to derive through somatic mutation from polyreactive low affinity autoantibodies that are encoded by a small set of unmutated V region genes in fetal and neonatal B cells. However, recent data exploring the physiologically expressed Ab repertoire and the importance of the stochastically generated heavy chain CDR3 (H-CDR3) in autoreactivity suggest that this scheme is incomplete. Here we analyzed via gene-swapping experiments and site-directed mutagenesis the relative contributions of the mutations in the light chain variable region (VL) and the heavy chain variable region (VH) domains and of the H-CDR3 in the autoreactivity of two IgM rheumatoid factors (RF), one a polyreactive low affinity Ab, the other a monoreactive high affinity Ab. These two RFs derived from the same V kappa III (humkv325) and VH1 (51p1) genes, but differed from each other by a few mutations and by the structure of the H-CDR3. The analysis of the reactivity patterns of different combinations of wild-type and in vitro engineered hybrid gene products clearly demonstrates the main influence of the H-CDR3 in the autoAb activity profiles. The results directly demonstrate the previously proposed hypothesis, namely, that the H-CDR3 plays a critical role in distinguishing poly- from monospecific RF. However, the data also indicate that self polyreactivity is a very fragile property and is dependent upon the primary structure of the VH segment.

Association of intermediate uveitis with HLA-A28: definition of a new systemic syndrome?

BACKGROUND

Endogenous posterior uveitis (PU) can be associated with systemic diseases, and certain forms have strong association with HLA antigens. Much less is known regarding intermediate uveitis (IU). The purpose of this study was to determine whether IU is associated with the HLA system and whether it can be associated with systemic symptoms.

METHODS

In 179 consecutive patients consulting for uveitis, a detailed history was obtained and a physical examination performed. HLA typing for 71 HLA-A, B, DR and DQ antigens, laboratory tests, and radiography of the chest, sinuses, and sacroiliac joints were systematically performed.

RESULTS

Thirty-two patients (18%) had IU; 51 (28.5%) had PU and constituted our internal control group. Nine of the patients with IU (28%) had the HLA-A28 antigen, compared with 8.1% of a healthy control population and 8.6% of the patients with PU (P < 0.001). An associated disease was found in four patients with IU (12.5%) (none was HLA-A28) and in 45% of the patients with PU (P < 0.01). Some 67% of HLA-A28 patients with IU had arthralgias affecting the knee(s), compared with 17% of non-HLA-A28 patients and 18% of patients with PU (P < 0.05 and P < 0.01 respectively); 55% had gonalgias and hypocomplementemia compared with 9% and 2% respectively (P < 0.01 and P < 0.001).

CONCLUSIONS

IU is significantly associated with HLA-A28; patients having this antigen may represent a subset of the disease characterized by an increased prevalence of arthralgias and hypocomplementemia.

Heavy chain variable region, light chain variable region, and heavy chain CDR3 influences on the mono- and polyreactivity and on the affinity of human monoclonal rheumatoid factors

Monoreactive high affinity pathologic autoantibodies were supposed previously to derive through somatic mutation from polyreactive low affinity autoantibodies that are encoded by a small set of unmutated V region genes in fetal and neonatal B cells. However, recent data exploring the physiologically expressed Ab repertoire and the importance of the stochastically generated heavy chain CDR3 (H-CDR3) in autoreactivity suggest that this scheme is incomplete. Here we analyzed via gene-swapping experiments and site-directed mutagenesis the relative contributions of the mutations in the light chain variable region (VL) and the heavy chain variable region (VH) domains and of the H-CDR3 in the autoreactivity of two IgM rheumatoid factors (RF), one a polyreactive low affinity Ab, the other a monoreactive high affinity Ab. These two RFs derived from the same V kappa III (humkv325) and VH1 (51p1) genes, but differed from each other by a few mutations and by the structure of the H-CDR3. The analysis of the reactivity patterns of different combinations of wild-type and in vitro engineered hybrid gene products clearly demonstrates the main influence of the H-CDR3 in the autoAb activity profiles. The results directly demonstrate the previously proposed hypothesis, namely, that the H-CDR3 plays a critical role in distinguishing poly- from monospecific RF. However, the data also indicate that self polyreactivity is a very fragile property and is dependent upon the primary structure of the VH segment.

Monoclonal IgM rheumatoid factor secreted by CD5-negative B cells during mixed cryoglobulinemia. Evidence for somatic mutations and intraclonal diversity of the expressed VH region gene

Mixed cryoglobulinemia is usually considered to be a nonmalignant human B cell proliferation that produces a monoclonal IgM rheumatoid factor (RF). Important immunologic similarities and differences were described between the monoclonal B cells during mixed cryoglobulinemia and during malignant chronic lymphocytic leukemia (CLL):high frequency of the same VH and V kappa gene usage by both types of monoclonal B cells producing IgM with RF activity, apparent intraclonal homogeneity, but different expression of the pan T cell CD5 Ag. The description of an unusual CD5-negative B cell CLL case secreting a mutated IgM RF led the authors to suggest that the usage of non-mutated germline Ig genes is a property of cells derived from the CD5 lineage or stage of differentiation, rather than an intrinsic property of CLL or of IgM RF-producing cells in general. Because mixed cryoglobulinemia cells are usually CD5-negative, it was of interest to test for the existence of mutations in the VH and V kappa regions, as well as for the intraclonal homogeneity of the expressed Ig genes. In this study, we used the PCR technique to analyze the monoclonal rheumatoid factor (mRF) V genes from a patient with mixed cryoglobulinemia. We show that the CD5-negative monoclonal B cells express a slightly mutated V kappa 3 gene, but a more mutated VH1 gene whose genomic counterpart was shown to be the 51p1 germline gene. The sequence analysis of several independent clones shows some degree of intraclonal diversity, suggesting the existence of a clonal filiation. These results are discussed in terms of the origin of the monoclonal B cell during mixed cryoglobulinemia and CLL.

Monoclonal IgM rheumatoid factor secreted by CD5-negative B cells during mixed cryoglobulinemia. Evidence for somatic mutations and intraclonal diversity of the expressed VH region gene

Mixed cryoglobulinemia is usually considered to be a nonmalignant human B cell proliferation that produces a monoclonal IgM rheumatoid factor (RF). Important immunologic similarities and differences were described between the monoclonal B cells during mixed cryoglobulinemia and during malignant chronic lymphocytic leukemia (CLL):high frequency of the same VH and V kappa gene usage by both types of monoclonal B cells producing IgM with RF activity, apparent intraclonal homogeneity, but different expression of the pan T cell CD5 Ag. The description of an unusual CD5-negative B cell CLL case secreting a mutated IgM RF led the authors to suggest that the usage of non-mutated germline Ig genes is a property of cells derived from the CD5 lineage or stage of differentiation, rather than an intrinsic property of CLL or of IgM RF-producing cells in general. Because mixed cryoglobulinemia cells are usually CD5-negative, it was of interest to test for the existence of mutations in the VH and V kappa regions, as well as for the intraclonal homogeneity of the expressed Ig genes. In this study, we used the PCR technique to analyze the monoclonal rheumatoid factor (mRF) V genes from a patient with mixed cryoglobulinemia. We show that the CD5-negative monoclonal B cells express a slightly mutated V kappa 3 gene, but a more mutated VH1 gene whose genomic counterpart was shown to be the 51p1 germline gene. The sequence analysis of several independent clones shows some degree of intraclonal diversity, suggesting the existence of a clonal filiation. These results are discussed in terms of the origin of the monoclonal B cell during mixed cryoglobulinemia and CLL.

Structure-function studies on a polyreactive (natural) autoantibody. Polyreactivity is dependent on somatically generated sequences in the third complementarity-determining region of the antibody heavy chain

SMI is a previously characterized IgM kappa polyreactive (natural) autoantibody. The variable regions of the heavy and light chains of SMI are respectively encoded by a nonmutated VH1 gene, designated 51p1, and a conserved nonmutated V kappa gene, designated Humkv325. These V genes seem to be over-represented in the autoimmune and fetal B cell repertoires, and to be frequently expressed in malignant B cells during certain lymphoid proliferations such as chronic lymphocytic leukemia. Polyreactive natural autoantibodies are thought to rely mainly on the use of such V genes in germ-line configuration. However, this model underestimates the contribution of the somatically generated heavy chain third complementarity-determining region (HCDR3) to autoantibody specificity. We used oligonucleotide site-directed mutagenesis to permute the sequence of the SMI-HCDR3 to generate a family of mutant proteins, each of which differed from the original SMI-IgM kappa by one amino acid residue. This allowed us to examine the relative contribution of selected amino acid residues in this region to the binding affinity of SMI against a panel of self-Ags. We found that a single amino acid substitution within the HCDR3 could dramatically alter the specificity of this autoantibody. Some substitutions abrogated the reactivity with all the tested Ags, whereas others changed the affinity or spectrum of reactivity for certain self-Ags. These results demonstrate that the autoantibody-binding activity of these conserved autoantibody-associated germ-line V genes is dependent upon heavy chain junctional sequences that are generated somatically during Ig gene rearrangement.

Structure-function studies on a polyreactive (natural) autoantibody. Polyreactivity is dependent on somatically generated sequences in the third complementarity-determining region of the antibody heavy chain

SMI is a previously characterized IgM kappa polyreactive (natural) autoantibody. The variable regions of the heavy and light chains of SMI are respectively encoded by a nonmutated VH1 gene, designated 51p1, and a conserved nonmutated V kappa gene, designated Humkv325. These V genes seem to be over-represented in the autoimmune and fetal B cell repertoires, and to be frequently expressed in malignant B cells during certain lymphoid proliferations such as chronic lymphocytic leukemia. Polyreactive natural autoantibodies are thought to rely mainly on the use of such V genes in germ-line configuration. However, this model underestimates the contribution of the somatically generated heavy chain third complementarity-determining region (HCDR3) to autoantibody specificity. We used oligonucleotide site-directed mutagenesis to permute the sequence of the SMI-HCDR3 to generate a family of mutant proteins, each of which differed from the original SMI-IgM kappa by one amino acid residue. This allowed us to examine the relative contribution of selected amino acid residues in this region to the binding affinity of SMI against a panel of self-Ags. We found that a single amino acid substitution within the HCDR3 could dramatically alter the specificity of this autoantibody. Some substitutions abrogated the reactivity with all the tested Ags, whereas others changed the affinity or spectrum of reactivity for certain self-Ags. These results demonstrate that the autoantibody-binding activity of these conserved autoantibody-associated germ-line V genes is dependent upon heavy chain junctional sequences that are generated somatically during Ig gene rearrangement.

Molecular analysis of rearranged VH genes during B cell chronic lymphocytic leukemia: intraclonal stability is frequent but not constant

Several genetic mechanisms have been shown to diversify the expressed antibody repertoire of committed B lymphocytes. These include V gene replacement, ongoing gene rearrangement and somatic hypermutation. These mechanisms may be operational at discrete points in the B cell differentiation pathway and generate idiotype diversity in various malignant B cell tumors. In particular, V region mutations have been established as a major mechanism of tumor escape from anti-idiotype immunotherapy in some lymphoma. On the other hand, previous studies on a few selected cases have shown that this mutation process does not affect the B cell clone during chronic lymphocytic leukemia. However, to what extent this intraclonal stability is a general phenomenon during B cell CLL is not clear. Therefore, we randomly selected 6 patients suffering from classical B cell CLL (sIgM (+), CD5 (+), CD19 (+)) at different stages of the disease and analysed the intraclonal variability of the expressed variable region of the heavy chain (VH). After PCR amplification of the cDNA corresponding to the rearranged VDJ regions, the products were cloned and sequenced. In five cases, multiple clone analysis did not show any intraclonal variability whatever the stage of the disease. Furthermore, in a single case, this intraclonal stability was confirmed during a three year period of time when the disease progressed. The sixth case behaved differently since we found multiple nucleotide substitutions, apparently accumulating as the malignant clone expanded. Besides the theoretical difficulties that these changes can induce during immunotherapy, two findings merit further discussion: 1) the distribution of the ongoing mutations affecting the VH region was not suggestive of an antigen driven selection, 2) this intraclonal variability was specific for the VH region, since the VL region showed no intraclonal variation.

Evidence that the V kappa III gene usage is nonstochastic in both adult and newborn peripheral B cells and that peripheral CD5+ adult B cells are oligoclonal

There is evidence that in certain situations the expressed antibody repertoire is dominated by small subsets of V gene segments. They include fetal, CD5+, and autoantibody-forming B cells as well as low grade B cell malignancies. For instance, inside the V kappa III family of approximately 10 members, only 3 (humkv325, 328, and Vg) are used recurrently for autoantibody production. However, the significance of this recurrence is difficult to interpret without a clear vision of the actual repertoire in normal subjects. To address this, we have sequenced and compared two sets of rearranged V kappa III genes generated by cDNA PCR amplification from a normal newborn, a normal adult, and from CD5+ B cells of the same adult donor. The results show that: (a) only four V kappa III gene segments are used by neonatal and total adult B cells (humkv325, humkv328, Vg, and kv305), humkv325 being overexpressed in both repertoires; (b) there is no significant difference in terms of V kappa III gene usage between the adult and newborn repertoires; (c) regarding the junction regions, there is a favored use of the most 5' JK gene segments (Jk1-Jk2); approximately 20% of the newborn and adult junction sequences was characterized by one or two additional codons, most probably resulting from a nontemplate addition of nucleotides; (d) adult clones, in contrast to most newborn clones, show sequence divergences from prototype sequences with patterns which suggest antigen-driven diversity; (e) regarding the adult CD5+ B cell library, it is most probable that the 78 clones analyzed derived from no more than nine different VK-JK rearrangements. Humkv325 is used by at least six of them, and most of the expressed V genes were in exact or very near germline configuration. Collectively these results suggest that the expressed antibody V kappa III repertoire in the adult represents only a fraction of the potential genetic information and that it resembles the preimmune repertoire of the neonate. The data, which also suggest that the adult peripheral blood CD5+ B cell population may be dominated by a small number of B cell clones, are discussed with regards to the V kappa III usage in pathological situations.

[Granulomatous mastitis, erythema nodosa and oligoarthritis. Apropos of a case]

The authors report a case of granulomatous mastitis associated with erythema nodosum and oligoarthritis. The skin and joint symptoms improved with potassium iodide. The breast lesion clinically simulated a tumor of high malignant grade. Granulomatous mastitis is a benign and rare disease. Its interest lies in the possible association with systemic manifestations and in its steroid responsiveness. This condition has been recently described as a distinct entity. When associated with systemic manifestations, sarcoidosis should be considered.