No abstract

The aim of this study was to investigate to which extent acute leukemias could be monitored for residual disease by using atypical antigen combinations as leukemia-related markers. Atypical antigenic features were determined by double color flow cytometry and included coexpression of lymphoid and myeloid related antigens, unphysiological coexpression of immature and mature antigens, and lack of an antigen that is normally expressed during maturation. Atypical immunophenotypes were detected in 35 of 68 patients with AML (51.5%) and 15 of 24 patients with ALL (62.5%). When 12 patients with leukemia-associated markers were again analyzed at relapse, the relevant antigen combinations were retained in 11 of them. The sensitivity of this two color flow cytometric assay as determined in dilution experiments was 1 in lo3 to lo4 cells.Follow-up studies of bone marrow samples revealed that, after induction chemotherapy cells with leukemia-associated markers were detectable in several patients at a frequency of 0.5 to 4%, but only patients in whom the cells with atypical antigens never disappeared suffered from relapse. In contrast, patients who became negative for the atypical cells remained in complete remission (median remission duration after the first negative bone marrow assessment by flow cytometry 52 weeks, range 20-102).We conclude that atypical antigen combinations, which are present in a meaningful number of acute leukemias, are a valuable means of monitoring acute leukemia patients during follow-up. This flow cytometric approach can complement other strategies to get a more accurate definition of remission in acute leukemia. o 1992 Wiley-Liss, Inc.

Summary. Chronic myeloid leukaemia (CML) dendritic cells (DC) are possible candidates for inducing antileukaemic immunity. This study aimed to investigate the frequency, phenotype and function of blood-derived leukaemic DC in comparison with DC from healthy donors using flow cytometric assays and mixed leucocyte reaction (MLR). Immature leukaemic DC displayed a reduced endocytotic capacity as compared with healthy controls. Moreover, in vitro maturation of leukaemic DC was found to be deficient. Expression of CD80, CD83, CD86, and major histocompatibility complex class I and class II antigens were reduced on lipopolysaccharide (LPS)-matured leukaemic DC but were enhanced by a mixture of interleukin 1b (IL-1b), IL-6, tumour necrosis factor-a (TNF-a) and prostaglandin E2 (PGE 2 ). Upon stimulation with bacterial LPS, intracellular TNF-a and IL-8 production was diminished in maturing DC from CML patients. This distinct cytokine deficiency was overcome when leukaemic DC were stimulated with cytokines/PGE 2 . MLR showed fully functional leukaemic DC after TNF-a-induced maturation, but a reduced proliferative alloresponse of leukaemic peripheral blood mononuclear cells. Further, intracellular production of cytokines in CMLderived T cells was markedly reduced. These data indicated that, in CML, the maturation response of leukaemic monocyte-derived DC to a natural stimulus like LPS is abnormal and may be caused by an aberrant TNF-a response in these cells. Thus, TNF-a alone or in combination with pro-inflammatory and T-cell stimulatory cytokines should be considered as an adjuvant for DC-based immunotherapy in CML.

We demonstrate that mainly 7S IVIG inhibits alloantigen-induced T-cell proliferation and generation of cytotoxic T lymphocytes. Reduced interleukin-2 (IL-2 ) protein levels in culture supernatants of IVIG-supplemented mixed lymphocyte reactions (MLR) but unchanged IL-2 mRNA levels strongly argue in favour of a post-transcriptional interference of IVIG with cytokines and/or cytokine production. Interferon-c ( IFN-c), soluble IL-2 receptor (sIL-2R) and monokines such as IL-1b, IL-6, IFN-a and tumour necrosis factor (TNF-a) were not affected by IVIG supplementation to MLR. Fc fragments were superior to F (ab∞) 2 -containing IVIG ( 5S and 7S IVIG) in inhibiting lectin stimulation of peripheral blood mononuclear cells ( PBMC), whereas natural killer ( NK) cytotoxicity was primarily inhibited by Fc-bearing IVIG (7S IVIG and Fc fragments), suggesting multiple mechanisms of IVIG immunomodulatory activity.

We tested the significance of the Ki-67 plasma cell growth fraction in 49 bone marrow samples from 42 patients with multiple myeloma (MM). As a new approach to study myeloma cell proliferation, strong positivity of the CD38 antigen as plasma cell related feature was simultaneously evaluated with nuclear Ki-67 expression in a flow cytometric double immunofluorescence assay. Mean Ki-67 values were significantly higher in MM at relapse (22.4 per cent +/- 10.4) as compared with MM at diagnosis (11.9 per cent +/- 8.4, p less than 0.005) and plateau-phase (10.0 per cent +/- 5.5, p less than 0.001), respectively. Serial observations in six patients confirmed this change in cell kinetic behaviour during the course of the disease. Elevated Ki-67 values correlated significantly with stage III (versus stage I, p less than 0.05), beta-2-microglobulin serum levels greater than 6 (p less than 0.001), plasmablastic morphology (p less than 0.001), and diploid myeloma cell DNA-content (p less than 0.005). No correlation was found between Ki-67 and immunoglobulin isotypes as well as immunophenotypic features (expression of CD10, CD33, and CD56) of myeloma cells. Clinically, six of seven patients with Ki-67 greater than 14 per cent at diagnosis had an unfavourable course (primary resistant disease or early relapse), and three of four patients with elevated Ki-67 values at plateau-phase relapsed within 3 months. Our results demonstrate the usefulness of Ki-67 in determining proliferative activity in MM and emphasize its value in the evaluation of the risk profile of MM patients.