Monoclonal rheumatoid factor-secreting cells in a patient with mixed cryoglobulinemia. Homogeneity and stability of the idiotypic production and in vitro idiotypic suppression.

The potential therapeutic value of anti-idiotypic antibodies during B cell proliferations largely depends on the stability of the target Ig idiotopes. We investigated this stability in a clinical condition of so called nonmalignant monoclonal B cell proliferation, mixed cryoglobulinemia. The idiotypic profile of a single IgM kappa monoclonal auto-antibody with anti-IgG activity (rheumatoid factor (RF] which originated from a patient suffering from a nonmalignant mixed cryoglobulinemia was followed over a period of 3 yr. As judged from the reactivity of a panel of five different mouse monoclonal anti-idiotypic antibodies mapping the RF variable regions, there was no idiotypic change in the serum IgM RF. At a cellular level, in vitro stimulation of the patient's PBL gives rise to IgM kappa auto-antibodies that were shown to bear the same idiotypic determinants as the serum IgM kappa. We then investigated the effects of the anti-idiotypic antibodies on the in vitro IgM kappa production. When stimulated with PWM and in the presence of anti-idiotypic antibodies (10 micrograms/ml), the patient's PBL produced less IgM RF (18 to 62% inhibition). The same inhibition of IgM RF production was observed after EBV infection of the patient's PBL (from 19 to 90% inhibition). In both cases, the remaining IgM RF production was idiotypically indistinguishable from the serum IgM RF. The implications of the idiotypic stability and of the results of in vitro idiotypic manipulation could be important in view of both the understanding of nonmalignant cryoglobulinemia and of the possible therapeutic use of anti-idiotypic antibodies in diseases.

Mapping of four light chain-associated idiotopes of a human monoclonal rheumatoid factor.

In an effort to analyze both IgM rheumatoid factor (RF) repertoire and regulation of RF production in humans, we developed a panel of four mouse monoclonal antibodies (mAb) defining distinct K light chain-associated idiotopes (id) of a human monoclonal IgM RF (Alt). These mAb (A75, AM1, AM2, AM3) had equivalent reactivities with the immunizing RF during classic inhibition of antigen-binding assays. These anti-id reagents were reacting to neither other tested monoclonal IgM RF nor normal polyclonal IgM. It was possible to distinguish the id defined by the mAb from the results of four sets of experiments: dissociation of Alt RF heavy (H) and light (L) chains showed that A75, AM1, and AM2 reacted to id located on the L chain, whereas AM3 defined a conformational RF id; recombination experiments of H and L chains showed that A75 and AM2 reacted well with both homologous (Alt H + Alt L) and heterologous (Alt L + unrelated H) recombinants, whereas AM1 reacted better with the homologous recombinant than with the heterologous one; the relative affinities of the mAb were drawn from their ability to shift already bound labeled Alt RF from solid phase IgG; and radiolabeling of two mAb (A75 and AM3) and experiments of inhibition of id binding with cold anti-id and cold anti-CK showed that A75 recognized a proximal id (close to the K constant region), whereas AM3 defined a more distal id, AM2 and AM1 being located between A75- and AM3-defined sites. This topographic mapping of K light chain-associated id of a human RF with anti-id of known relative affinities could help in studying idiotypic regulation in humans.

Autologous bone marrow transplantation in acute myeloid leukemia in relapse or in complete remission.

We report ten cases of acute myeloid leukemia treated by intensive therapy followed by autologous bone marrow transplantation. Seven patients were in first relapse, and three were in complete remission. The conditioning regimen consisted of either chemotherapy alone (6-thioguanine, cytarabine, lomustine, and cyclophosphamide [TACC; eight patients]) or cyclophosphamide and total-body irradiation (two patients). All the patients in first relapse achieved complete remission (CR). The median remission duration was 9.9 months (range, 5-14), and the median survival was 14.4 months (range, 9-23.8). Of the three patients autografted during CR, one relapsed at Month 5 and two others remain in CR and are well at 18+ and 18.3+ months. High-dose chemotherapy followed by autologous bone marrow transplantation seems to be a valuable treatment for acute myeloid leukemia, if it is used immediately after the CR to consolidate the remission.

[Autologous haematopoietic stem cell transplantation. Preliminary results of a regional multicentric study (author's transl)]. / Greffe de cellules-souches hématopoïétiques autologues. Premiers résultats d'un protocole régional (author's transl)]

Autologous bone marrow transplantation represents a new approach to the treatment of malignant diseases when conventional therapy has failed. For this reason, the authors have collected bone marrow from 46 patients, including 24 with acute leukaemia, 7 with chronic myeloid leukaemia, 10 with lymphosarcoma and 5 with solid tumours. The mean of total cryopreserved CFU-c was 8.5 X 10(6) (range: 0.2-25). Ten cases of autologous bone marrow transplantation are reported. Seven patients had been prepared with high dosage chemotherapy alone (TACC) and three with chemotherapy combined with total body irradiation. Haematopoiesis restarted within 9 to 15 days in 5 patients and within 22 to 34 days in the other 5. Complete remission was obtained in all 5 patients with acute myeloid leukaemia grafted during their first relapse, the longest remission up to now being 390 days. One patient with chronic granulocytic leukaemia is still in second chronic phase after 360 days. Stem cells were transplanted early in the course of a T-lymphosarcoma, during complete remission; maintenance chemotherapy was withdrawn, and the chances of success of this treatment alone are being evaluated. The kinetics of blood and bone marrow CFU-c populations after transplantation were studied in 4 cases and were found to correlate closely with haematopoietic recovery following ablative bone marrow therapy. Stem cell transplantation can only be justified in acute leukaemia if it is carried out immediately after complete remission to consolidate the results and, hopefully, to prolong the remission.