Human CD5-positive B cells in lymphoid malignancy and connective tissue diseases

Biochemical biomarkers for multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is the most frequent demyelinating disease of the central nervous system. Although there is currently no definite cure for MS, new therapies have recently been developed based on a continuous search for new biomarkers.

DEVELOPMENT

MS diagnosis relies on the integration of clinical, imaging and laboratory findings as there is still no singlepathognomonicclinical feature or diagnostic laboratory biomarker. The most commonly laboratory test used is the presence of immunoglobulin G oligoclonal bands (OCB) in cerebrospinal fluid of MS patients. This test is now included in the 2017 McDonald criteria as a biomarker of dissemination in time. Nevertheless, there are other biomarkers currently in use such as kappa free light chain, which has shown higher sensitivity and specificity for MS diagnosis than OCB. In addition, other potential laboratory tests involved in neuronal damage, demyelination and/or inflammation could be used for detecting MS.

CONCLUSIONS

CSF and serum biomarkers have been reviewed for their use in MS diagnosis and prognosis to stablish an accurate and prompt MS diagnosis, crucial to implement an adequate treatment and to optimize clinical outcomes over time.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

The dietary supplement ephedrine induces b-adrenergic mediated exacerbation of systemic lupus erythematosus in NZM391 mice

The dietary supplement and adrenergic receptor agonist ephedrine has been a controversial topic as its safety has been questioned. b-adrenergic receptor (b-AR) activation causes immunomodulation, which may contribute to promotion of autoimmune pathology. This report investigated the ability of ephedrine to exacerbate processes associated with autoimmune disease in a lupus-prone mouse model. To mimic human supplementation, ephedrine was administered to NZM391 (lupus-prone) and BALB/c (nonlupus prone) mice orally twice a day for three months at a dose of 50 and 100 mg/day. Some ephedrine-treated NZM391 mice also were preadministered the b-AR antagonist propranolol to investigate b-AR involvement. Mice were bled monthly, and sera were assayed for a variety of lupus manifestations and immunological measurements. In NZM391 males and females, both doses of ephedrine significantly increased lupus manifestations, including IgG production and organ-directed autoantibody titers, and significantly lowered the ratio of IgG2a/IgG1 compared to controls. Ephedrine significantly decreased female lifespan and significantly increased circulating populations of plasma cells (CD38hi CD19lo cytoplasmic IgG+) and CD40+ B1a cells, while preventing an age-related decrease in the B1a cell population expressing a high level of CD5. While ephedrine induced gender-specific immunomodulation in BALB/c mice, increases in the lupus manifestations of anti-dsDNA titers and serum urea nitrogen were not detected. Preadministration of propranolol decreased lupus manifestations and serum levels of IgG and IgE in ephedrine-treated mice, but did not block the shift towards IgG1 production. These findings indicate that ephedrine via b-AR can exacerbate lupus symptoms in NZM391 mice and that blockade of the b-ARs on B cells, and not T cells, apparently was of greater importance as the inhibition of lupus symptoms corresponded to an inhibition of immunoglobulin levels, not a change of Th1/Th2 balance.

Phenotypic abnormalities of peripheral blood mononuclear cells in patients with Behçet's disease and association with HLA-B51 expression

The aim of this study was to investigate the subclasses and the immunophenotypic profile of peripheral mononuclear cells in patients with Behçet's disease (BD) and to assess associations between the expression of HLA-B51 antigen and that of other cell markers. Thirty healthy volunteer blood donors and forty patients with BD were enrolled into this study. Phenotyping was performed using two color flow cytometry. HLA-B51 typing was performed using the complement dependent microlymphocytotoxicity assay. Unlike controls, patients with BD presented a modified immunophenotypic profile of lymphocytes. Compared to those in the remission phase, patients with active BD showed an increased mean of MFI ratio of CD56 on CD16+CD56+ cells (32.47 ± 14.26 versus 23.87 ± 10.3; p = 0.032), increased absolute numbers of CD4(-)CD8(bright) and CD4(+)CD8(+) cells (657.1 ± 463.6 cells/µL versus 319.24 ± 116.4 cells/µL; p = 0.017 and 40.77 ± 36.41 cells/µL versus 10.77 ± 9.78 cells/µL; p < 0.0001, respectively) and an elevated mean of MFI ratio of CD19 on B cells (252.3 ± 56.7 versus 205.67 ± 32.3; p = 0.021). However, expression of HLA-B51 was not associated with any specific immunophenotypic profile. In conclusion, abnormal immunophenotypic profile of peripheral lymphocytes was found in patients with BD, especially in active phase, reflecting an immune dysregulation. Moreover, HLA-B51 expression was not found to be related to the expression of other cell markers.

Decreased CD5⁺ B cells in active ANCA vasculitis and relapse after rituximab

BACKGROUND AND OBJECTIVES

B cell significance in ANCA disease pathogenesis is underscored by the finding that ANCA alone can cause disease in mouse models and by the effectiveness of rituximab as therapy in ANCA-small vessel vasculitis (ANCA-SVV). To avoid infections and adverse events from therapy, clinicians require improved markers of disease activity and impending relapse to guide immunosuppression strategies after rituximab treatment.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The B cell phenotype was investigated in patients with active ANCA-SVV and in remission. From 2003 to 2009, 54 patients were followed longitudinally for 4-99 months and compared with 68 healthy controls. In a subset of 19 patients, the B cell immunophenotype was examined in samples after rituximab therapy.

RESULTS

Patients with active ANCA-SVV had lower %CD5(+) B cells, whereas %CD5(+) B cells from patients in remission were indistinguishable from healthy controls. After rituximab, median time to relapse was 31 months in patients maintaining normalized %CD5(+) B cells, with or without maintenance immunosuppression. Among patients whose B cells repopulated with low %CD5(+) B cells or had a sharply declining %CD5(+) B cells, those who were on low or no maintenance immunosuppression relapsed sooner (median 17 months) than patients who were maintained on high levels of oral maintenance immunosuppression (29 months; P=0.002).

CONCLUSIONS

The %CD5(+) B cells, as a component of the human B regulatory cell phenotype, is a useful indicator of disease activity, remission, and future relapse, and thus may guide remission maintenance therapy after rituximab treatment.

Increased peripheral blood CD5+ B cells predict earlier conversion to MS in high-risk clinically isolated syndromes

Clinically isolated syndrome patients (CIS) with oligoclonal IgG bands (OCGB) are at high risk for clinically definite multiple sclerosis (MS). However, the outcome for individual patients is unpredictable and the search for reliable blood markers predicting early conversion to multiple sclerosis (MS) has clinical relevance. CD5+ B cells (CD5+Bc) are involved in some autoimmune diseases. This study investigated whether high blood CD5+Bc percentage can predict CIS conversion to MS. Fifty-five consecutive CIS showing OCGB were prospectively studied. Every patient underwent a brain MRI study and a flow cytometry analysis of CD5+Bc percentage. Conversion to MS was studied during follow-up. The CD5+Bc percentage was assessed in 40 controls and a cut-off value of 3.5% (mean+2 SD) was calculated. A blood CD5+Bc percentage above this value predicted earlier conversion to MS in the whole group (hazard ratio [HR]: 3.40; 95% confidence interval [CI]: 1.69-6.68; p=0.0005) and in CIS patients fulfilling three or more Barkhof-Tintoré criteria plus OCGB, who showed higher risk for MS (HR: 3.79; 95% CI: 1.86-15.32; p=0.0018). Multivariate analysis also showed a predictive value for high blood CD5+Bc count (HR: 4.3; 95% CI: 1.9-9.5; p<0.0001). It was concluded that high percentages of CD5+Bc independently associate with increased risk of early conversion to MS in CIS patients with OCGB and Barkhof-Tintoré criteria.

Skin lesions in chronic lymphocytic leukemia

Cutaneous lesions occur in up to 25% of patients with chronic lymphocytic leukemia (CLL). These can be caused by either cutaneous seeding by leukemic cells (leukemia cutis, LC) and other malignant diseases or nonmalignant disorders. Skin infiltration with B-lymphocyte CLL manifests as solitary, grouped, or generalized papules, plaques, nodules, or large tumors. Prognosis in CLL patients with LC is rather good and many authors claim that it does not significantly affect patients' survival. However, prognosis is poor in patients in whom LC shows blastic transformation (Richter's syndrome) and when leukemic infiltrations in the skin appear after the diagnosis of CLL. Secondary cutaneous malignancies are also frequent complications in patients with CLL. A higher risk was seen in skin cancer, for which eightfold higher occurrence has been stated. There are some suggestions that alkylating agents and purine analogs may be associated with an increased incidence of secondary malignancies in CLL. Nonspecific, secondary cutaneous lesions are frequently observed in CLL patients. The most common secondary cutaneous changes seen in CLL are those of infectious or hemorrhagic origin. Other secondary lesions present as vasculitis, purpura, generalized pruritus, exfoliative erythroderma, and paraneoplastic pemphigus. An exaggerated reaction to an insect bite and insect bite-like reactions have been also observed.

Systemic antineutrophil cytoplasmic antibody vasculitis in a patient with chronic lymphocytic leukemia

There might be rheumatic manifestations of malignant diseases, especially those of the hematological type. Until now, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in chronic lymphocytic leukemia (CLL) has been reported on only very few occasions. Here, we present our patient with Rai stage II CLL who came to us with constitutional symptoms. She turned out to have hematuria with dysmorphic erythrocytes and developed hemoptysis. She had pulmonary-renal syndrome and was diagnosed with p-ANCA positive microscopic polyangiitis. She is currently using prednisolone and cyclophosphamide and undergoing regular hemodialysis. Constitutional symptoms in patients with hematological malignancies should make the physicians consider systemic vasculitis after exclusion of disease-related complications.

B cell conducts the lymphocyte orchestra

The interest for B cells has recently been revived. They normally play a role in the development, the regulation, as well as the activation of lymphoid architecture: they regulate dendritic cells and T-cell subsets function through cytokine production. Receptor editing is also essential in B cells and aids in preventing autoimmunity. Both abnormalities in the distribution of B-cell subsets and clinical benefit response to B-cell depletion in autoimmune states illustrate their importance. A new area has thus been reached, whereby B lymphocytes return as a significant contributor to autoimmune disorders.

B Lymphocytes Are Required for Development and Treatment of Autoimmune Diseases

Recent studies have revealed that B cells serve extraordinarily diverse functions within the immune system in addition to antibody production. These functions contribute to autoimmunity. They initiate the development of lymphoid architecture and regulate dendritic and T-cell function through cytokine production. Receptor editing is also essential to prevent autoimmunity. Both abnormalities in the distribution of B-cell subsets and the benefits of ablative B-cell therapy of autoimmune states confirm their importance. Results from transgenic models have demonstrated that the sensitivity of B cells to antigen receptor cross-linking correlates to autoimmunity, with particular reference to negative signaling by CD5 and CD22. These mechanisms maintain tolerance by recruiting src-homology 2 domain-containing protein tyrosine phosphatase-1. These findings open new prospects for immunotherapy of autoimmune diseases.

Production of Heymann nephritis by a chemically modified renal antigen

An autoimmune kidney disease morphologically and functionally similar to Heymann nephritis (HN) was induced in mature male Sprague Dawley rats by repeated weekly IP injections of a chemically modified azo sonicated ultracentrifuged (u/c) rat kidney fraction 3 (rKF3) antigen in an aqueous medium. The experiment was terminated 15 weeks after the first injection of the chemically altered antigen. Serum samples collected and analysed by an indirect fluorescent antibody test on normal rat kidney sections during the course of the experiment showed a gradual rise in circulating pathogenic autoantibodies directed against the proximal tubular brush border regions. Proteinuria was present and significantly increased in the urine of two of eight rats. The arising immune-complex glomerulonephritis (ICGN) revealed typical HN kidney disease lesions in 70% of the rats in histological, direct fluorescent antibody and electron-microscopical examinations. Control rats injected similarly with the an unmodified version of the same antigen did not develop the HN-characteristic morphological and functional changes. To our knowledge, this is the first time that the autoimmune kidney disease designated as an active HN has been produced by the administration of a chemically altered renal antigen in an aqueous solution and not by the usual presentation of the nephritogenic renal antigen in an adjuvant.

The V(lambda)-J(lambda) repertoire of patients with systemic lupus erythematosus manifests characteristics of the natural antibody repertoire

OBJECTIVE

To understand in detail the mechanisms of autoantibody production in patients with systemic lupus erythematosus (SLE), we performed a comprehensive analysis of the normal human immunoglobulin light chain V(lambda) repertoire and compared it with the V(lambda) repertoire in SLE patients.

METHODS

The SLE V(lambda) repertoire of B cells obtained from 3 SLE patients was analyzed and compared in detail with the V(lambda) repertoire of IgM+ B cells obtained from 3 human fetal spleens and IgM+,CD5+ B cells obtained from 2 normal adults. Conventional IgM+,CD5- B cells obtained from normal adults were used as controls. V(lambda)-J(lambda) rearrangements were amplified from the genomic DNA of individual B cells by polymerase chain reaction.

RESULTS

The expressed V(lambda) repertoire of SLE patients contained several similarities with the expressed repertoire of the fetus and the adult CD5+ B cells. The V(lambda) genes 3L and 1G were overexpressed in the fetus, the adult CD5+ B cells, and the patients with SLE. The selection for rearrangements with restricted junctional diversity by utilization of homology-mediated joining, together with diminished N nucleotide addition, was a prominent feature of fetal, adult CD5+, and SLE B cell repertoires. Furthermore, profound expansion of V(lambda) clones with identical third complementarity-determining regions was observed in the adult CD5+, fetal, and SLE B cell repertoires. Notably, significant numbers of expanded adult CD5+ B cells, fetal, and SLE V(lambda) clones utilized homology-mediated joining at the V(lambda)-J(lambda) junctions.

CONCLUSION

These data demonstrate that the SLE V(lambda)-J(lambda) repertoire manifests characteristics of normal adult IgM+,CD5+ and fetal B cell populations that are known to be enriched for the production of natural autoantibodies.

Increased peripheral blood B-cells expressing the CD5 molecules in association to autoantibodies in patients with lupus erythematosus and evidence to selectively down-modulate them

The present investigation has been undertaken to analyze absolute and relative CD5+ B-cell numbers in patients with lupus erythematosus (LE), and concomitant B-CLL, and to monitor them under therapy. Peripheral blood lymphocytes of LE-patients, and healthy controls were analyzed by flow cytometry and direct immunofluorescence technique. Patients were treated with low-dose methotrexate (MTX). Before and during MTX treatment laboratory monitoring has been done. LE-patients had increased percentages of CD5+CD19+ as compared to controls (p < 0.0002), the absolute number of CD5+ B-cells was equal in controls and patients. Autoantibodies were positively correlated to the number of CD5+ B-cells in LE-patients. In a total of 140 LE-patients one male patient suffered from both LE and B-CLL (0.7%). He had increased absolute and relative CD5+ B-cells. MTX induced significant decrease of both total B-cell numbers, and CD5+ B-cells. The decrease of CD5+CD19+ cells was more pronounced than the decrease of total B-cells. Apoptosis rate increased in parallel to the drop-down of elevated CD5+CD19+ cells. Peripheral T-cell subsets remained stable under low-dose MTX. Both absolute and relative numbers of CD5+CD19+ cells should be taken into account in patients with LE. MTX seems to decrease B-cells, and preferentially to down-regulate B-cells expressing the CD5 molecule, which opens new therapeutic options and cell biological activities. The mechanism is unclear but apoptosis induction seems to be likely.

Prevalence and pattern of antinuclear autoantibodies in 347 patients with non-Hodgkin's lymphoma

The presence of antinuclear autoantibodies (ANA) was investigated in a large cohort of patients with non-Hodgkin's lymphoma (NHL) in order to assess their frequency, specificity and prognostic relevance. ANA were analysed in 347 patients with different histological subgroups of NHL and in 213 controls using an indirect immunofluorescence technique on HEp2 cells. As the appearance of autoantibodies may be found after treatment of NHL, samples were collected at the time of diagnosis of NHL before any therapy. Sixty-six (19%) NHL patients and 12 (5.6%) patients from the control group displayed ANA. The prevalence between the two groups was found to be significantly higher in NHL patients (P < 0.0001) with a marked increased prevalence in follicular and mantle cell lymphoma subgroups. Autoantibodies directed against mitotic proteins or mitotic-associated proteins were found in 6.9% of NHL patients versus 0.5% in the control group (P < 0.001), with a significantly increased incidence in follicular and mantle cell lymphoma subgroups (P < 0.0001). Some 28% of the patients with positive ANA displayed clinical symptoms that could correspond to classical autoimmune manifestations, this frequency appearing to be higher in the marginal zone/mucosa-associated lymphoid tissue lymphoma subgroup. These data demonstrate a significant incidence of ANA before any treatment in NHL occurrence, which seems to be higher in some histological subgroups with particular ANA, such as ANA directed against mitotic proteins or mitotic-associated proteins.

Establishment and characterization of new B-cell precursor leukemia cell line NALM-35

A novel B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) cell line, NALM-35, was established from the peripheral blood of a 40-year-old woman at diagnosis of ALL. Imunophenotyping showed BCP type III characteristics including expression of TdT, CD10, CD19, CD22, CD79a and HLA class II. T-cell and myeloid-associated antigens tested were negative except CD5 and CD28. The surrogate light chains CD179a and CD179b were positive. NALM-35 cells have the morphological appearance of lymphoblasts. Cytogenetic analysis of NALM-35 revealed an abnormal karyotype with 46, XX, add(9)(p11). Southern blot analysis of the immunoglobulin genes status of NALM-35 at 10 months after establishment showed germ line configuration of the kappa and lambda light chain genes, and rearrangement of the mu heavy chain gene. DNA fingerprinting, chromosomal analysis and immunophenotyping proved that NALM-35 was clonally derived from the primary leukemia cells. The established cell line may provide a useful model system and unprecedented opportunities for analyzing the multitude of biological aspects of normal and neoplastic B-lymphocytes and their precursors.

The occurrence and significance of V gene mutations in B cell-derived human malignancy

The classification of B cell tumors has relevance for refining and improving clinical strategies. However, consensus has been difficult to establish, and although a scheme is now available, objective criteria are desirable. Genetic technology will underpin and extend current knowledge, and it is certain to reveal further subdivisions of current tumor categories. The Ig variable region genes of B cell tumors present a considerable asset for this area of investigation. The unique sequences carried in neoplastic B cells are easily isolated and sequenced. In addition to acting as clone-specific markers of each tumor, they indicate where the cell has come from and track its history following transformation. There is emerging clinical value in knowing whether the cell of origin has encountered antigen and has moved from the naive compartment to the germinal center, where somatic mutation is activated. This is amply illustrated by the subdivision of chronic lymphocytic leukemia into two subsets, unmutated or mutated, each with very different prognosis. Other tumors may be subdivided in a similar way. Microarray technology is developing rapidly to probe gene expression and to further divide tumor categories. All these genetic analyses will provide objective data to enhance both our understanding of B cell tumors and our ability to treat them.

Low-grade non-Hodgkin's lymphoma in a patient with systemic lupus erythematosus

Coexistence of systemic lupus erythematosus (SLE) with low-grade non-Hodgkin's lymphoma (LGNHL) has been described occasionally in the literature with the potential pathogenetic role of monoclonal B CD5+/CD19+ cells. We report a case of LGNHL which developed 18 months after diagnosis of SLE. The monoclonal population of lymphocytes in the peripheral blood and bone marrow was CD5/CD19 negative but CD19/CD22 positive. The SLE responded well to treatment with prednisone and the course of the LGNHL was stable and cytotoxic treatment was not required.

Analysis of V(H)-D-J(H) gene transcripts in B cells infiltrating the salivary glands and lymph node tissues of patients with Sjögren's syndrome

OBJECTIVE

In patients with Sjögren's syndrome (SS), B lymphocytes have been found to infiltrate salivary glands, resulting in sialadenitis and keratoconjunctivitis. The disease is frequently associated with benign and neoplastic lymphoproliferation. The present study was undertaken to investigate whether clonal B cell expansion takes place in lymphocytic infiltrations of salivary glands under (auto- [?]) antigen stimulation, by analyzing in more detail the variable part (V(H)-D-J(H)) of the immunoglobulin heavy chain genes expressed in these B cells.

METHODS

Biopsies of the labial salivary glands and lymph nodes were performed on 2 female patients with SS. The Ig gene rearrangements in these tissues were amplified by reverse transcriptase-polymerase chain reaction using specific primers.

RESULTS

A total of 94 V(H)-D-J(H) transcripts were cloned and sequenced. Our data suggest a polyclonal origin of the B cell infiltrates. In 92 of the transcripts, V(H) genes were modified by somatic mutation. Further analysis showed counterselection for replacement mutations within the framework regions, suggesting that those B cells were stimulated and selected for functional expression of a surface Ig. In labial salivary glands from both patients, clonally related B cells became evident. Members of 1 particular clone were found in both the lip and lymph node material.

CONCLUSION

These data provide evidence, on the nucleotide sequence level, that an antigen-triggered clonal B cell expansion takes place in the salivary glands of patients with SS who do not have histologic evidence of developing lymphoma. It may be speculated that those B cell clones expand during disease progression, resulting in lymphomagenesis.

Production of anti-erythrocyte antibodies by leukemic and nonleukemic B cells in chronic lymphocytic leukemia patients

We have assessed the specificity of antibodies from the leukemic B cells of five patients with both chronic lymphocytic leukemia and autoimmune hemolytic anemia (CLL-AHA). Leukemic cells from one patient displayed surface immunoglobulin with heavy and light chain isotypes identical to that of the patient's anti-red blood cell (RBC) antibodies, and the leukemic cells secreted antibodies in vitro with anti-RBC activity. However, in the remaining patients, the leukemic cells displayed surface immunoglobulin with light chain isotypes different from that of the patient's anti-RBC antibodies and secreted antibodies in vitro with no detectable anti-RBC activity. Thus, there are two distinct classes of CLL-AHA patients, differentiated by the presence or absence of an anti-RBC antibody-producing leukemic B cell clone. The apparent heterogeneity in the source of pathogenic anti-RBC antibodies may impact the treatment response of the two classes of CLL-AHA patients.

Anti-CD5 extends the proliferative response of human CD5+ B cells activated with anti-IgM and interleukin-2

The CD5 T cell glycoprotein which is expressed by a subset of B cells has been shown to be involved in T cell activation and proliferation. No similar studies, to date, have addressed the role of CD5 on the B cell subset. CD5+ and CD5- B cells were sorted and stimulated with anti-CD5 monoclonal antibody (mAb) in vitro. The activation and proliferative responses of these two populations, as measured by analysis of proliferation marker, did not differ following anti-mu and interleukin (IL)-2 stimulation. The addition of anti-CD5 did not change the responsiveness of such activated CD5+ B cells but resulted in a decrease in CD25 expression. Pre-activation of B cells with phorbol 12-myristate 13-acetate, which increased CD5 expression, failed to alter the proliferative response of CD5+ B cells to anti-mu and IL-2 with or without addition of anti-CD5 mAb. Anti-mu and IL-2 treatment of CD5+ cells resulted in optimal proliferation measured at day 3 which decreased by day 6. However, addition of anti-CD5 mAb at day 3 prevented this decline in proliferative response. This dose-dependent effect was observed only when the anti-CD5 mAb was presented to the B cells in cross-linked form. Co-stimulation of CD5 did not lower the threshold of antigen to which the B cells responded. Taken together, these data support a functional role for CD5 on B cells acting as an accessory signal, following their primary activation through the B cell receptor complex and highlight differences in the role of CD5 associated with the T cell receptor complex.

B lymphocytes and humoral immune responses in rheumatoid arthritis

Although the etiology of rheumatoid arthritis (RA) remains unknown at present, major evidence implicates humoral immune mechanisms in the pathophysiology of this disease. The primary lesions occur in the synovium and are characterized by immunological activation and chronic inflammation. Activated B cells and plasma cells secrete antibodies including rheumatoid factors and anticollagen antibodies. These antibodies give rise to immune complex formation and activation of the inflammatory cascade. There is no evidence that rheumatoid factor secreting B cells act as antigen presenting cells and present immune complex to T cells, leading to perpetuation of the inflammatory response.

Autoimmune phenomena in non-Hodgkin's lymphoma

In order to obtain valid data on the pattern, frequency and prognostic significance of autoimmune derangements in non-Hodgkin's lymphoma (NHL) we studied 626 consecutive adult NHL patients participating in a population-based lymphoma registry. A total of 86 patients, corresponding to 13.7%, showed autoimmune phenomena (AP). Of these, 7.8% exhibited clinical autoimmune phenomena (CAP), and 5.9% showed immunohaematological phenomena (IHP). The distribution of histological subgroups of NHL in the AP and non-AP patients was similar. The same holds true for the CAP and IHP patients. A slight, non-significant overrepresentation of NHL, T-cell phenotype was found in patients with AP. CAP preceded the diagnosis of NHL in most patients, whereas IHP was associated with active lymphoma disease. AP as a whole did not predict for time to complete response, time to relapse or for survival. The finding that IHP patients relapsed earlier than CAP patients was not reflected in a significant difference in survival.