Role of interleukin 10 in the B lymphocyte hyperactivity and autoantibody production of human systemic lupus erythematosus.

Interleukin-10 (IL-10) is produced at a high level by B lymphocytes and monocytes of patients with systemic lupus erythematosus (SLE). In the present work, we analyzed whether this increased production of IL-10 contributed to the abnormal production of immunoglobulins (Ig) and of autoantibodies in SLE. The role of IL-10 was compared with that of IL-6, another cytokine suspected to play a role in these abnormalities. The spontaneous in vitro production of IgM, IgG, and IgA by peripheral blood mononuclear cells from SLE patients was weakly increased by recombinant IL (rIL)-6, but strongly by rIL-10. This production was not significantly affected by an anti-IL-6 mAb but was decreased by an anti-IL-10 mAb. We then tested the in vivo effect of these antibodies in severe combined immunodeficiency mice injected with PBMC from SLE patients. The anti-IL-6 mAb did not significantly affect the serum concentration of total human IgG and of anti-double-stranded DNA IgG in the mice. In contrast, the anti-IL-10 mAb strongly inhibited the production of autoantibodies, and, to a lesser extent, that of total human IgG. These results indicate that the Ig production by SLE B lymphocytes is largely IL-10 dependent, and that the increased production of IL-10 by SLE B lymphocytes and monocytes may represent a critical mechanism in the emergence of the autoimmune manifestations of the disease.

Treatment of rheumatoid arthritis with anti CD4 monoclonal antibody. Open study of 25 patients with the B-F5 clone.

Twenty-five defined severe RA patients (pts) (17 F, 8 M) were treated in an open study with a CD4 murine monoclonal antibody (Mab) (B-F5 clone, IgG1). Mab's daily dose was 10 mg (1 pt), 15 mg (2 pts), 20 mg (17 pts), 30 mg (4 pts) and 50 mg (1 pt) for 10 days. Tolerance was fair. Clinical improvement occurred during treatment period or within the first month in all but 2 patients, irrespective of Mab dosage. Improvement duration was variable (1 to 12 months), half of the patients still show signs of improvement at month 4. Biological parameters (CRP) improved parallel to the clinical. At day 180, 25% of the patients showed a reduction of 50% or more of the initial CRP values. There is no modification of RF titers, renal and hepatic parameters. Sequential evaluation showed a decrease of B, TCD3, CD4, CD8 lymphocytes and monocytes two hours after Mab infusion and return to baseline in 20 hours. Xenogenic immunization occurred in 6 patients without influence upon clinical response. These modifications are moderate and transient and do not account for the more prolonged effect in some cases, nor do they offer any prediction of further clinical response.

Monoclonal antibodies in human organ transplantation and auto-immune diseases.

The usefulness of monoclonal antibodies (mAbs) in the transplantation field has become evident over the last couple of years. Different mAbs have been used as a prophylactic treatment after transplantation, in a therapeutic way against acute organ rejection and new diagnostic tools to predict clinical rejection immerge. One can even hope that with humanised mAbs or human mAbs obtained by repertoire cloning the formation of human anti-mouse antibodies will be solved although on the one hand this appeared not to be a big problem and on the other hand anti-idiotypic antibodies can still be expected. However, the most puzzling question is how the mAbs modulates the immuno-response and this not only in organ rejection but also in auto-immune diseases. Only one out of many CD25 mAbs with seemingly similar epitope recognition can be used in therapeutical treatment of acute Graft versus Host Disease. The same mAb is not, however, very efficient in the prophylactic treatment of kidney transplantation without association of suboptimal doses of cyclosporin A. Another example is a CD4 mAb which is efficient in the treatment of polyarthritis with no side effects but which provokes transient but clear side effects when used in psoriasis or multiple sclerosis patients. A second CD4 mAb with high inhibitory activity in several bioassays compared to the first CD4 mAb has no beneficial effect at all on polyarthritis. Also the question why there is a percentage of "no response" patients among apparently identical "good response" patients remains unanswered. However it becomes clear from these experiences that: 1) mAbs recognizing a similar epitope and being of the same isotype will not automatically have the same effect in therapy. 2) side effects may be depending of the disease treated. 3) the activities of mAbs in bioassays and even animal models very often do not reflect the in vivo situation in human. 4) efficiency of the treatment with mAbs can be increased by a better understanding of the mode of action and increased efficiency can be expected by association of several mAb or mAb with drugs for the "no response" patients and should be the next step in the therapeutical use of mAbs.

Human recombinant dimeric IL-6 binds to its receptor as detected by anti-IL-6 monoclonal antibodies.

Three different epitopes of the human IL-6 (IL-6) molecule were recognized by the mAb B-E4 (IgG2b), B-E8 (IgG1) and B-F6 (IgG1). The affinities of these three mAb for IL-6 differ little in several assays but if ranked by affinity they fall into the following order B-E8 greater than B-E4 greater than B-F6. B-E4 and B-E8 mAb, recognizing two different epitopes, are inhibiting mAb in the bioassay with the IL-6 depending cell line B9, however B-E8 has an inhibiting activity higher than B-E4. Both human natural IL-6 (HnIL-6) and human recombinant IL-6 (HrIL-6) were inhibited but not the murine natural IL-6 (MnIL-6). Surprisingly, not only the non-inhibiting mAb (B-F6) recognizes the HrIL-6 fixed to the receptor but also the inhibiting mAb B-E4 and B-E8. This together with the results obtained in a sandwich ELISA where the same mAb was used as both catcher and tracer to detect HrIL-6, it was concluded that dimeric HrIL-6 is able to fix the IL-6 receptor. Competition studies between monomeric HnIL-6 and dimeric HrIL-6 showed that the affinity of the dimeric HrIL-6 for the receptor was higher than that of HnIL-6.

Therapeutic use of monoclonal anti-CD4 antibody in rheumatoid arthritis.

Ten patients with severe rheumatoid arthritis were treated with a murine monoclonal anti-CD4 (B-F5) antibody in an open study (one with 10 mg/day, 2 with 15 mg/day, 7 with 20 mg/day) for 10 consecutive days. Tolerance was excellent. All patients improved during treatment clinically (Ritchie's index, morning stiffness, pain scale) (p = 0.005), as well as biologically C-reactive protein (p = 0.008) with an average 60% reduction of each of these variables at Day 15, and clinical benefit lasted over 6 months in some patients. No significative depletion was noted in total lymphocyte or CD3, CD4, CD8, CD20, positive cells after treatment. Evidence of murine immunization was found in only 2 patients.

Treatment of corticosteroid resistant acute graft-versus-host disease by in vivo administration of anti-interleukin-2 receptor monoclonal antibody (B-B10)

In a multicenter pilot study, 32 patients showing steroid-resistant acute graft-versus-host disease (GVHD) were treated by in vivo administration of anti-interleukin-2 (IL-2) receptor monoclonal antibody (MoAb B-B10). Twenty-three patients received marrow from HLA-matched related donors, four from matched unrelated donors and five from partially matched related donors. The overall grade of GVHD was II in 16 patients, III in two, and IV in five. Five milligrams of B-B10 MoAb was infused in bolus daily for 10 days and then every second day for a further 10 days in an attempt to reduce GVHD recurrence. No clinical side effects were noted during the B-B10 treatment period. A complete response (CR) acute GVHD was achieved in 21 patients (65.6%). Six patients (18.7%) showed partial improvement (PR) and 5 patients (15.6%) no response (NR). A significant factor associated with GVHD response was the delay between the onset of the GVHD and the first day of B-B10 infusion. The earlier B-B10 was introduced, the greater the probability of CR (P = .03). There was no correlation between the serum B-B10 level and GVHD response (P = .69). There was, however, a significant correlation between the clinical response and the B-B10 kinetics as a function of time: serum B-B10 levels attained a plateau level more rapidly in the CR group than in the PR/NR group. Among the 26 complete and partial evaluable responders, GVHD recurred in 10 cases (38.4%). Host anti-B-B10 MoAb immune response occurred in only one (7.1%) of the 14 patients analyzed. Fourteen of the 32 patients (43.7%) are currently alive between 2 and 14 months after GVHD treatment with B-B10 was completed.