High incidence of spontaneous Ig-producing lymphocytes in peripheral blood and synovial fluid of patients with active seropositive rheumatoid arthritis

Immunoglobulin G and A antibody responses to Bacteroides forsythus and Prevotella intermedia in sera and synovial fluids of arthritis patients

The objective of the present study was to investigate immunoglobulin G (IgG) and IgA antibody immune responses to Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, and Candida albicans in the sera of patients with rheumatoid arthritis (RA), the synovial fluid (SF) of patients with RA (RA-SF samples), and the SF of patients without RA (non-RA-SF samples). An enzyme-linked immunosorbent assay was used to determine IgG and IgA antibody levels in 116 serum samples from patients with RA, 52 RA-SF samples, and 43 non-RA-SF samples; and these were compared with those in SF samples from 9 patients with osteoarthritis (OA-SF samples) and the blood from 100 donors (the control [CTR] group). Higher levels of IgG antibodies against B. forsythus (P < 0.0001) and P. intermedia (P < 0.0001) were found in non-RA-SF samples than in OA-SF samples, and higher levels of IgG antibodies against B. forsythus (P = 0.003) and P. intermedia (P = 0.024) were found in RA-SF samples than in OA-SF samples. Significantly higher levels of IgA antibodies against B. forsythus were demonstrated in both RA-SF and non-RA-SF samples than in OA-SF samples. When corrected for total Ig levels, levels of IgG antibody against B. forsythus were elevated in RA-SF and non-RA-SF samples compared to those in OA-SF samples. Lower levels of Ig antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group for both IgG (P = 0.003) and IgA (P < 0.0001). When corrected for total Ig levels, the levels of IgG and IgA antibodies against B. forsythus were still found to be lower in the sera from patients with RA than in the plasma of the CTR group (P < 0.0001). The levels of antibodies against P. gingivalis and C. albicans in the sera and SF of RA and non-RA patients were comparable to those found in the respective controls. The levels of IgG and IgA antibodies against B. forsythus were elevated in SF from patients with RA and non-RA-SF samples compared to those in OA-SF samples. Significantly lower levels of IgG and IgA antibodies against B. forsythus were found in the sera of patients with RA than in the plasma of the CTR group. This indicates the presence of an active antibody response in synovial tissue and illustrates a potential connection between periodontal and joint diseases.

High IgE in rheumatoid arthritis (RA) patients is complexed with anti-IgE autoantibodies

This study presents data on more than 300 RA and allergic patients analysed for their serum levels of anti-immunoglobulin isotype autoantibodies and IgE. We observed high levels of IgE in sera of RA and allergic patients. Interestingly, we measured significantly higher specific IgE levels against Alternaria but not against nine other allergens in the RA compared with the allergic group. As expected, anti-IgG autoantibodies (rheumatoid factors (RF)) of different isotypes were detected in sera from RA patients only. However, we found increased titres of complexed anti-IgE autoantibodies in all RF+ groups and in the allergic group. These findings may explain why despite elevated IgE levels a decreased prevalence of allergic diseases in RA patients has been observed.

Pre-B lymphocytes with intracytoplasmic mu chains in the peripheral blood of rheumatoid arthritis patients

A dysregulation of B-cell differentiation and activation has long been evidenced in rheumatoid arthritis (RA). Such analyses have, however, usually focused on the latest stages of B-cell development. Using a classical technique of immunofluorescence labeling on cytospins, we investigated the presence of peripheral pre-B lymphocytes in 92 RA patients and 23 controls. Cells with intracytoplasmic mu chains were evidenced in 58.7% of the RA patients studied, ranging between 0 and 30%, while small numbers of c-mu cells, never exceeding 6% of peripheral blood lymphocytes, were observed in 9 controls. Relationships between this feature and clinical or laboratory data were investigated, showing a negative correlation between the percentage of c-mu + lymphocytes and Ritchie's index (P = 0.05), the number of tender or swollen joints (P = 0.05), erythrocyte sedimentation rate (P = 0.005), seropositivity (P = 0.05), and disease duration (P = 0.01).

Characterization of B cell growth in systemic lupus erythematosus. Effects of recombinant 12-kDa B cell growth factor, interleukin 4 and transforming growth factor-beta

B cells from systemic lupus erythematosus (SLE) patients have been shown to be hyperactive as measured by proliferation and immunoglobulin production. We find that B cells from 6 of 13 SLE patients, in the absence of prior activation, respond two to three times better to recombinant 12-kDa B cell growth factor (BCGF) than do normal or rheumatoid arthritis B cells (p less than 0.005). B cells from normally responsive SLE patients require an anti-mu antibody activation step to generate similar proliferative signal in response to r12-kDa-BCGF. There are no clinical or serological parameters that distinguish these hyperresponsive SLE patients from the normally responsive SLE patients. The combination of r12-kDa-BCGF and interleukin 4 (IL4) gives an enhanced response with both normal and SLE B cells. Transforming growth factor type beta (TGF-beta) suppresses the response to r12-kDa-BCGF in a dose-dependent fashion using B cells from both healthy donors and SLE patients. We conclude that peripheral blood B cells are in an activated state (as detected by response to 12-kDa-BCGF) in approximately 50% of SLE patients. These B cells respond normally to regulation by IL4 and TGF-beta. A therapeutic approach aimed at reducing the B cell hyperactivity in SLE would involve suppressing the effects of 12-kDa-BCGF and IL4 while at the same time enhancing the effects of TGF-beta.

Regulation of isotype immunoglobulin production by adjuvants in vivo

Mice were immunized against fluorescein isothiocyanate (FITC)-labelled human gamma globulin (HGG) or dextran sulphate (DXS) in the absence or presence of different adjuvants. The immune response was assayed as the total Ig-secreting cells and FITC-specific plaque-forming cells (PFC) found in various lymphoid organs. The adjuvants influenced the isotype of antibodies produced to the same antigenic determinant. The PFC of different IgG subclasses were favoured by different adjuvants. The IgG3 isotype was produced mainly after immunization with either antigen and lipopolysaccharide (LPS) or Li salt as adjuvant; IgG1 was produced with incomplete Freund's adjuvant (IFA), complete Freund's adjuvant (CFA), alum, poly I:C, Quil A, Be salt, and poly A:U. Some of the above adjuvants (Be salt and poly A:U) favoured the production of IgG2b, and others (CFA, alum, Quil A, and poly I:C) favoured the IgG2a isotype besides the main isotype. Attempts were made to correlate the activation by the various adjuvants of certain TH subtypes with the isotypes produced.

Synovial fluid from rheumatoid arthritis patients induces polyclonal antibody formation in vivo

Our previous studies demonstrated the presence of a T-cell replacing factor in the synovial fluid (SF) of patients with rheumatoid arthritis (RA) and that RA-SF can activate, selectively, the induction of IgG2b antibody secreting cells in lipopolysaccharide (LPS)-pretreated mouse spleen cell cultures. In the present study the effect of RA-SF was tested in vivo in mice. Injection of the polyclonal activator LPS induced the production of IgM and IgG3 secreting cells in normal mice. However, the addition of RA-SF led to a selective increase in the production of IgG2b with a peak response on day 5 and IgG1 plaque-forming cells (PFC) with a peak on day 7. Neither the IgG2b nor IgG1 responses were caused by specific immunity against heterologous proteins present in RA-SF, as injection of in vitro inactive RA-SF samples did not induce PFC. The effect on B cells of RA-SF was further evaluated by injection of RA-SF in combination with LPS to the Xid B-cell deficient CBA/N mice. RA-SF had identical effects in CBA/N as in normal mice. The biological implication of these findings is discussed. Our earlier results support the idea that B cells are endogenously activated in RA patients. We have speculated that this activation is caused by the B-cell differentiation factor which is present in SF. Therefore, we also tested whether RA-SF could influence antibody-forming cells in mice that spontaneously develop autoimmunity. We found that injection of RA-SF alone, in the absence of any other activating substance, induced a very marked increase of IgG producing cells in (NZW x NZB) F1 hybrid mice. From a relatively high background level the RA-SF could still induce an up to 100-fold increase in the numbers of PFC in spleens of such mice.

Polyclonal B-cell activation in periodontitis

The evidence that periodontitis-associated bacteria contain potent PBA factors is very strong. Clearly, antibodies directed against non-oral antigens are produced in the inflamed periodontal lesion, and PBA appears to contribute to that production. It is also clear that B cells and plasma cells are the major cell types in the periodontal lesion. Furthermore, alterations in the regulation of B-cell responses to PBA factors are associated with severe periodontal disease. However, evidence demonstrating that activated B cells and plasma cells are directly involved in the pathogenic mechanisms leading to destruction of the periodontal support is still circumstantial. Polyclonal B-cell activation and potential pathways by which PBA-stimulated cells could be involved in periodontal destruction remain largely hypothetical. It appears that IL-1 is an important osteoclast-activating agent, and that LPS, which is a potent PBA factor in many systems, can elicit IL-1 production by B cells as well as by the monocyte/macrophage lineage. Recent data indicating that IL-1 is produced by numerous malignant B-cell lines lend support for the idea that B-cell IL-1 could be important in bone resorption. It is also likely that polyclonal activation may lead to production of autoantibody such as anti-type I and anti-type III collagens, and the destruction of self tissues through ADCC reactions, immune complex formation, and complement activation. Further research is needed to determine how the B cell/plasma cell may participate in tissue injury in periodontitis, and how the B-cell response to PBA factors is regulated.

B-cell growth-promoting activity in supernatants from CD4+ cells from synovial fluid and peripheral blood of patients with rheumatoid arthritis and other inflammatory arthritides

The purpose of this study was to compare CD4+ cells from peripheral blood (PB) and synovial fluid (SF) of patients with rheumatoid arthritis with regard to mitogen-induced production of B-cell growth-promoting activity. CD4+ cells were isolated by a direct immunomagnetic technique and supernatants from both unstimulated and mitogen-stimulated CD4+ cells were studied. B-cell growth-promoting activity was assayed using highly purified B cells obtained from peripheral blood of healthy individuals. The indicator B cells were isolated by an indirect immunomagnetic technique and solid-phase anti-mu was used for activation of the B cells. Supernatants of unstimulated CD4+ cells from SF and PB did not contain B-cell growth-promoting activity, while usually high levels of B-cell growth-promoting activity were detected in the supernatants from mitogen-stimulated cultures. There was no significant difference in the B-cell growth-promoting activity level between supernatants from SF CD4+ and patient PB CD4+ cells, nor was there any significant difference between SF CD4+ and control PB CD4+ supernatants. The results indicate that the CD4+ cells in the SF have a normal potential for producing B-cell growth-promoting activity.

Biological characterization of T cell-replacing factor in the synovial fluid of rheumatoid arthritis patients

The synovial fluid of patients with rheumatoid arthritis (RA) contains a biologically active factor which has the ability to replace T cells for the induction of antibody secretion by human blood lymphoid cells stimulated by pokeweed mitogen (PWM) in vitro. This factor, which will be referred to as RA-SF (synovial fluid), also has the capacity to act as a B cell-stimulatory factor of mouse splenic lymphocytes in the presence of lipopolysaccharide (LPS). Using a test system developed for the definition of interleukin 4 (IL-4), which is a B cell-stimulating lymphokine which preferentially activates the synthesis of selected Ig classes in mouse lymphoid cells, we have shown that RA-SF has properties similar to IL-4 in that it induces differentiation of antibody secretion in the LPS-pretreated mouse cell, but unlike IL-4, which gives IgG1 and IgE, it selectively induces IgG2b synthesis. The present study demonstrates that RA-SF has a biological activity that is reminiscent of other B cell-stimulating mouse lymphokines, but it is biologically distinct from IL-2, IL-4, and IL-5. Recent data also indicate that it is distinct from gamma interferon (IFN-gamma). Therefore, we conclude that the biological activity of RA-SF has properties in common with a T-cell replacing (TRF) and B-cell differentiation factor (BCDF) and probably represents yet another biological activity which so far lacks an experimental counterpart. The relevance of this factor for autoantibody synthesis is discussed.

Polyclonal antibody secretion during acute graft-versus-host disease

Spontaneous plaque-forming cells (S-PFC) were followed in 67 bone marrow transplantation (BMT) recipients and 41 controls. Patients with no acute graft-versus-host disease (GVHD) had decreased IgA and IgM S-PFC up to 7 weeks after BMT compared with controls. Patients with acute GVHD had increased IgG, IgA, and IgM PFC compared with controls and patients without GVHD during the first 4 weeks after BMT. The maximum number of S-PFC increased with increasing severity of acute GVHD. However, at diagnosis of GVHD there was no difference in S-PFC in patients who resolved their GVHD or in those who developed more severe GVHD. After 6 weeks, patients with acute GVHD had significantly decreased IgA and IgM S-PFC compared with normal. No major changes in S-PFC were induced during various infections. However, a patient who developed urticaria had a dramatic increase in S-PFC. Patients studied more than a year after BMT had reduced IgM S-PFC compared with controls. It is concluded that S-PFC are reduced after BMT, but markedly enhanced during acute GVHD.

Differential expression of Ia antigens by rheumatoid synovial lining cells

The differential expression of Ia antigens was studied in freshly isolated rheumatoid nonlymphoid synovial lining cells (SLC) and rheumatoid synovial fibroblast cell lines cultured in the presence of Interferon-gamma, using a large panel of anti-Ia reagents with monomorphic or polymorphic specificities. All the HLA-DR or -DQ specificities detectable on the corresponding peripheral blood B cells were also expressed in freshly isolated SLC. However, in all instances, the number of DR-positive SLC exceeded the percentage of cells expressing DQ antigens. In addition, the epitope expression of Ia antigens varied within the DR or DQ populations of Ia molecules as revealed by polymorphic reagents. Double-label experiments or using the ingestion of Latex particles as a marker demonstrated that the synovial macrophages (type I SLC) primarily bear the DR+DQ+ phenotype, while there is an additional population of nonphagocytic SLC (previously termed type II SLC) that has a DR+ and monocyte marker negative phenotype but did not have detectable levels of DQ antigens as analyzed by both fluorescence microscopy and cell sorter analysis. This latter population frequently had a morphology showing dendritic processes and rapidly lost the expression of Ia antigens upon culture. Cells with a similar, primarily DR+ phenotype were readily obtained in synovial fibroblast cultures after treatment with Interferon-gamma. These data suggest that there are two populations of Ia+ synovial lining cells: the synovial macrophages (type I cells) with the DR+DQ+ phenotype, and cells probably related to fibroblasts with a DR+ phenotype without detectable DQ antigens (type II cells). The fact that the latter phenotype could be induced by Interferon-gamma treatment of cultured synovial fibroblasts suggests that this mediator may have a similar role in vivo in the activation of certain synovial cell populations.

Mononuclear cells in synovial fluid of rheumatoid arthritis patients undergoing joint surgery

Analysis of synovial fluid from patients with rheumatoid arthritis (RA) and a long history of RA, who were undergoing synovectomy and joint surgery, revealed that 71 +/- 15% of the mononuclear cells in the synovial fluid were lymphocytes. 3 +/- 2% lymphoid blast cells, and 26 +/- 15% of monocytes/macrophages. The lymphocyte population consisted mainly of T cells, and 72 +/- 15% of lymphocytes were OKT11-positive. OKT8-positive cells (48 +/- 9%) dominated over OKT4-positive (32 +/- 8%) cells with a mean OKT4/OKT8 ratio of 0.69. On the basis of Ia- and Tac-markers, very few of the lymphocytes were activated. Few B cells (12 +/- 7%) and no plasma cells were seen. The results are discussed in relation to previous reports.

Humoral immune function in severe, active rheumatoid arthritis

Peripheral blood mononuclear cells (PBMC) from 30 patients with definite or classic active rheumatoid arthritis who were on no remittive drugs were studied for spontaneous and pokeweed mitogen (PWM)-stimulated immunoglobulin plaque-forming cell frequency (IgPFC), spontaneous IgM-rheumatoid factor (IgM-RF) secretion, and in vitro proliferative responses to soluble recall antigens. Rheumatoid spontaneous total (IgG + IgM + IgA) IgPFCs were higher than those of normal controls when assayed after 7 days in culture. Spontaneous and PWM-stimulated IgM-PFCs, in contrast, were significantly less than normal regardless of when assayed. Spontaneous synthesis of IgM-RF was observed in 56% of the RA patients, but absolute amounts produced were widely heterogeneous. Spontaneous IgM-RF production by RA PBMC was associated with low or absent spontaneous IgM-PFC production. Moreover, a strong association was found between the median amount of IgM-RF secreted and depressed proliferative responses to soluble recall antigens. Our results define several abnormalities of immunoglobulin production in a clinically homogeneous and highly active rheumatoid population and delineate methodologic variations that can complicate the interpretation of similar data in the literature. In addition, our findings suggest that subgroups of rheumatoid patients that show distinct cellular and humoral immune abnormalities can be identified.

Inhibition of T cell-dependent antibody production by D-penicillamine. Different requirements for Cu2+ in suppression of polyclonal and antigen-specific B cell responses

The effects of D-penicillamine (D-Pen) on the production of immunoglobulins (Ig) and anti-microbial antibodies (Ab) by human mononuclear cells (MNC) cultured in vitro were analysed by haemolytic plaque forming cell (PFC) assays. Polyclonal Ig and Ab production, induced by pokeweed mitogen (PWM), was not affected by D-Pen in pharmacologically relevant concentrations, unless Cu2+ was added. Likewise, D-Pen + Cu2+, but not D-Pen alone, affected polyclonal Ig production induced by Epstein-Barr virus. The production of interleukin-2 and B cell growth factor by phytohaemagglutinin-stimulated T cells was not inhibited by D-Pen; again D-Pen + Cu2+ markedly reduced the production of these cytokines. By contrast, D-Pen significantly reduced the antigen-induced antibody production without requirement of additional Cu2+. Addition of cytokine-containing supernatant to MNC treated with D-Pen + Cu2+ tended to increase the PWM-induced Ig responses, but had no effect on the antigen-induced Ab production of MNC cultured with D-Pen. Thus, the mechanisms by which D-Pen suppresses polyclonal and antigen-induced B lymphocyte responses are different.

T-cell helper activity and B-cell function of synovial and blood lymphocytes from patients with rheumatoid arthritis or other forms of chronic arthritis

The helper effect of T cells on B-cell immunoglobulin (Ig) responses induced by pokeweed mitogen (PWM) or purified protein derivative of tuberculin (PPD) was studied in lymphocytes from synovial fluid (SF) and blood of nine patients with rheumatoid arthritis (RA) and eight patients with other forms of chronic arthritis. In PWM cultures the helper effect of SF T cells on Ig responses (IgG, IgM, IgA) of autologous and allogeneic blood B cells was lower than that of blood T cells (P less than 0.01). This decrease was more pronounced in patients with RA than in patients with non-RA. In PPD cultures no significant difference was found between the helper effect of SF T cells and blood T cells on the Ig responses of allogeneic blood B cells or on the IgG response of autologous blood B cells, whereas the helper effect of SF T cells on the IgM and IgA responses of autologous blood B cells was decreased. The Ig responses to PWM or PPD in cocultures of autologous blood B and T cells were not significantly different between patients and healthy controls. The PWM- and PPD-induced Ig responses of SF B cells were lower than those of blood B cells when cocultured with autologous blood T cells. SF B cells produced IgG but usually little IgM and IgA. Thus there was a dysfunction of SF B cells and of SF T cells in a PWM-driven system, but a fairly good helper function of SF T cells in a PPD-driven system.

Evidence for oligoclonal B cell expansion in the peripheral blood of patients with rheumatoid arthritis

Peripheral blood lymphocytes from patients with rheumatoid arthritis and osteoarthritis were examined for evidence of oligoclonal B cell expansion using the computer assisted flow cytometric technique of kappa-lambda (kappa-lambda) analysis. Eleven of 29 patients with rheumatoid arthritis but only one of 16 with osteoarthritis gave abnormal results (p less than 0.025). Abnormal kappa-lambda determinations did not correlate with age, duration of disease, presence of rheumatoid factor, or other clinical and laboratory parameters. Therapy with oral or intramuscular gold compounds appeared to diminish the incidence of kappa-lambda abnormality. These findings may indicate defective control of clonal B cell proliferation in rheumatoid arthritis.

Spontaneous immunoglobulin synthesis by peripheral mononuclear cells in active rheumatoid arthritis

Spontaneous production of immunoglobulins (Igs) by peripheral blood mononuclear cells (PBMC) in vitro was investigated to assess B cell activity in a group of 24 patients with rheumatoid arthritis (RA) with or without active joint disease and with or without rheumatoid vasculitis (RV) at the time of study. PBMC of patients with active arthritis (Ritchie index above 16) produced significantly more IgG and IgA than those of patients with inactive joint disease or those of 12 healthy controls. Enhanced production of IgG was found mainly among RA patients with concomitant RV, whereas markedly enhanced IgA production could also be found in patients without symptoms of RV. IgM production was only enhanced in two patients who had both active arthritis and RV. High production of IgG and IgA was probably due to increased numbers of Ig-secreting cells among freshly isolated PBMC, since the concentrations of Ig produced in vitro rose steadily, starting on day 0 and persisting throughout the entire culture period. Moreover, IgG and IgA concentrations measured after 7 days of culture showed significant correlations with the numbers of IgG- and IgA-containing plasma cells in PBMC on day 0. Comparison of the spontaneous production of Igs by PBMC with the levels of circulating immune complexes (CIC), showed that CIC levels were also significantly higher in active arthritis and in RV, but that there was no correlation between the CIC levels in individual patients and Ig production by their PBMC in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis of antibodies, including antiviral antibodies, in the knee joints of patients with arthritis

Serum and synovial fluids from 16 patients with seronegative arthritis and eight with rheumatoid arthritis were studied for immunoglobulin levels and for antibody levels to five viruses. When allowances were made for the distribution of immunoglobulins between serum and synovial fluid there was evidence that in several patients antibody to one or more viruses was synthesised locally in the joint. IgG and especially IgM were present in greatly increased amounts in arthritic joints compared with normal joints. On the basis of serum/synovial fluid ratios inflammation and local immunoglobulin synthesis are discussed as possible causes. These results are compared with antiviral antibody and immunoglobulin ratios observed in the serum and cerebrospinal fluid of patients with multiple sclerosis.

Effect of drug therapy on circulating and synovial fluid Ig-secreting cells in rheumatoid arthritis

A common immunological abnormality in rheumatoid arthritis (RA) is an increased spontaneous polyclonal B cell activation. In order to study the influence of drug therapy in RA on the functional activity of B cells we enumerated spontaneous plaque-forming cells (PFC) in peripheral blood lymphocytes (PBL) and synovial fluid lymphocytes (SFL) by a reverse haemolytic plaque assay. Spontaneous IgG-, IgM-, and IgA-PFC in PBL of 26 patients with classical erosive RA receiving either gold salts or D-penicillamine were similar to those observed in 20 healthy controls. In contrast, significantly higher numbers of IgG- and IgA-PFC, but not IgM-PFC, were found in PBL of nine patients with classical erosive RA receiving non-steroidal anti-inflammatory drugs (NSAID) alone. Furthermore, spontaneous PFC in SFL from 16 consecutive patients with RA receiving second-line drugs, as well as 17 patients with other forms of arthritis (non-RA) were generally low and significantly less than those observed in 20 RA patients on NSAID alone. Moreover, a wide individual variation in PFC, especially in relation to the IgG class, was recorded in the synovial lymphocytes. These studies imply that treatment with second-line drugs is associated with normalisation of B cell activity in RA patients, and that the effect can be detected at the cellular level both in blood and synovial fluid.

Demonstration of a helper factor(s) with T-cell-replacing activity in synovial fluid

Cell-free synovial fluid (SF) obtained from patients with rheumatoid arthritis contains a helper factor(s) capable of augmenting the generation of plaque-forming cells (PFC) in pokeweed mitogen (PWM)-stimulated normal peripheral blood mononuclear cells (PBMC). This helper factor behaves like a polyclonal B-cell activator, in that it triggers the formation of IgM, IgG, and IgA PFC. However, SF has little or no effect on the proliferation of PWM-activated PBMC. Furthermore, SF was capable of replacing T cells for PWM-induced differentiation but not proliferation of enriched human blood B lymphocytes. No helper factor or T-cell-replacing activity was found in SF from patients with traumatic synovitis. Fractionation of SF containing helper activity on staphylococcal protein A column indicated that the activity is induced by biologically active molecules distinct from materials that preferentially bind to protein A such as IgG immune complexes. We conclude that the present activity has striking similarities to the recently described B-cell differentiation factor that is produced by specifically activated T-cell lines in vitro.

B cell differentiation factor in synovial fluid of patients with rheumatoid arthritis

In this paper we have summarized our findings on immune activity in patients with Rheumatoid Arthritis. RA is characterized not only by the formation of various autoantibodies but also of a hyperreactivity of the B cell system, shown as an increased DNA synthetic rate of blood non-T, non-monocytic lymphocytes as well as an increased number of actively antibody secreting cells both in the blood and the synovial fluid. Synovial fluid contains biological activity which synergizes with PWM for the induction of Ig-secreting cells in blood from healthy controls. The factor can also substitute for T cells in the PWM-induced antibody synthesis in vitro. This activity fits well with the finding that SF contains a factor which induces increased formation of IgG in LPS-pretreated mouse cell cultures. Experiments show that the factor leads to a preferential increase in the production of IgG2b antibody secreting cells. Therefore, we conclude that synovial fluid contains a B cell differentiating factor with a selective effect on the induction of a particular IgG subclass.

Spontaneous and induced immunoglobulin secretion by synovial fluid B lymphocytes in rheumatoid arthritis

The functional properties of B lymphocytes in synovial fluid (SF) from patients with rheumatoid arthritis (RA) were analysed by means of a reverse haemolytic plaque forming cell (PFC) assay. SF mononuclear cells spontaneously secreted IgG, but little IgM or IgA. The SF cells failed to respond to the polyclonal B cell activators pokeweed mitogen (PWM) and Epstein-Barr virus. However, SF B cells cocultured with autologous T lymphocytes from the blood and stimulated with PWM secreted IgG but little IgM or IgA. The PFC responses of blood B cells cocultured with autologous SF T cells in the presence of PWM were low; irradiation of the T cells increased the blood B lymphocyte responses, but the differences were not statistically significant. It is concluded that suppressor SF T cells may be partly responsible for the poor response of SF B cells to PWM.

Adjuvants influence the immunoglobin subclass distribution of immune responses in vivo

Mice were immunized against fluorescein isothiocyanate (FITC)-labelled human gamma globulin (HGG) in the absence or presence of different adjuvants. The immune response was assayed every other day with regard to both total Ig-secreting cells and FITC-specific plaque-forming cells (PFC). The adjuvants influenced the type of immune response induced to the same antigenic determinant. Thus, addition of Freund's complete (FCA) or incomplete (FIA) adjuvant preferentially led to the secretion of IgG1 PFC of an average high affinity. Most newly appearing IgG-secreting cells were also detected as FITC-specific PFC. The use of lipopolysaccharide (LPS) as an adjuvant resulted in the induction of both IgM and IgG, particularly of the IgG3 and IgG2b subclasses. However, these antibodies had relatively low affinity, and a large number of total IgG-secreting cells induced by LPS had no detectable FITC specificity. The FCA/FIA- and LPS-induced responses to FITC-HGG were additive when injected together, indicating that they act on distinct subpopulations of B lymphoid cells. The adjuvant response to LPS, but not the response to FCA/FIA, was totally absent in mice of the C3H/Hej strain, which are non-responders to the polyclonal activating properties of LPS. Finally, the response induced by FCA or FIA was T-cell-dependent and the LPS response T-cell-independent as assayed in nude mice.

Spontaneous DNA synthesis in rheumatoid arthritis: evidence of enhanced circulating non-T-cell proliferation

3H-thymidine incorporation in cultures of peripheral blood mononuclear cells from patients with seropositive rheumatoid arthritis (RA) and healthy controls was measured in vitro in the absence of added stimulants. A significantly higher level of spontaneous DNA synthesis was found in cultures of mononuclear cells from patients with clinically active RA than from patients with inactive disease and normal controls. This activity was more apparent in 24-h cultures than in 72-h cultures. There was no correlation between DNA levels and IgM rheumatoid factor (RF) titres. When T- and non-T-cell populations were separated and cultured simultaneously with unfractionated cells, only non-T cells maintained high levels of DNA synthesis, and enrichment of surface membrane Ig+ (SmIg) cells was generally associated with enhancement of 3H-thymidine incorporation. Furthermore, no difference was found in spontaneous DNA synthesis between cultures either containing or depleted of phagocytic cells. Moreover, the addition of graded numbers of autologous monocytes to highly purified T- and non-T-cell populations did not alter the background DNA synthesis. Thus, endogenously activated cells in RA patients are neither T lymphocytes nor monocytes. A regulatory influence by monocytes could not be demonstrated. It is suggested that cells actively engaged in DNA synthesis in RA blood are non-T cells in origin, most probably B lymphocytes.

IgG rheumatoid factor-secreting lymphocytes in rheumatoid arthritis: evaluation of a haemolytic plaque-forming cell technique

A haemolytic plaque-forming cell (PFC) assay detecting human B lymphocytes secreting IgG rheumatoid factor (RF) was established using sheep erythrocytes (SRBC) sensitized with rabbit IgG, developing rabbit anti-human IgG, and complement. IgG-RF PFC were only demonstrated with IgG-depleted guinea-pig serum as the source of complement. Cells spontaneously secreting IgG-RF were found among synovial fluid mononuclear cells (mean, 134/10(6)) and synovial tissue mononuclear cells (mean, 1775/10(6)) from patients with rheumatoid arthritis, whereas few were recorded among blood lymphocytes (mean, 3/10(6)). The experiments revealed that the RF-IgG PFC were protein-synthesizing B lymphocytes. The antibody specificity of the secreted IgF-RF was verified by the inhibitory effect of exogenous human and rabbit IgG on PFC formation.

Immunosuppressive actions of gold salts

In rheumatoid arthritis both lymphocyte-mediated and antibody-mediated immune reactions are important for the inflammatory lesions. In vivo activated B lymphocytes/plasma cells, T lymphocytes and monocytes/macrophages (Mo) are intimately involved in the disease process. Several clinical observations suggest an immunosuppressive action of gold salts. In humans, gold salts interfere with a number of Mo functions in vitro, including cellular interactions between Mo and T lymphocytes. Some workers have shown that the activation of human T lymphocytes is inhibited by gold salts, most probably secondary to an inhibition of Mo-T cell cooperation. Recent experiments indicate that gold salts also affect the in vitro differentiation of human B lymphocytes in response to polyclonal activators. Both the gold atom and the SH group seem to be important for the immunosuppressive actions of gold salts.