Characterization of normal and regenerating bone marrow cells with a panel of monoclonal antibodies

To obtain baseline data for the diagnosis of residual leukaemia or lymphoma in bone marrow (BM), BM samples of 12 normal adults, 6 patients treated with chemotherapy for solid tumours and 6 patients treated with chemotherapy for leukaemia or lymphoma during remission were assessed with a panel of monoclonal antibodies by fluorescence microscopy immediately following chemotherapy. A large variability between normal individuals was found concerning the percentages of T lymphocytes and T cell subsets, B lymphocytes, HLA-DR+ and OKT10+ cells, due to variation in BM composition and, presumably, peripheral blood contamination. The regenerating BM cells also showed a large variability and, in addition, sometimes very high percentages (up to 19%) of CALLA+, c mu + s mu-, c mu + kappa lambda- and TdT+ cells were found. The interpretation of data on individual BM samples of patients assessed for leukaemia or lymphoma should therefore be related to: the amount of contaminating peripheral blood cells; the cellular composition of the BM samples as determined by May-Grünwald Giemsa staining; baseline data of age-matched normal controls and of regenerating BM of patients without haematological diseases.

Rapid down-regulation of protein kinase C and membrane association in phorbol ester-treated leukemia cells

Peripheral blood lymphocytes from patients with chronic lymphocytic leukemia (CLL) acquire after several days of exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA) several morphological, immunological and histochemical features of hairy cell leukemia. We have investigated the short term effects of TPA treatment on protein kinase C and its subcellular distribution. Within minutes of addition of TPA to CLL cells 20% of the cytosolic protein kinase C had associated with the particulate fraction. The remaining 80% of protein kinase C activity was down-regulated. The association with the membrane dramatically increased the resistance of the enzyme to inhibition by the non-ionic detergent, Triton X-100. These results suggest that activation of protein kinase C causes multiple biological changes in CLL cells.

Identification of malignant plasma cell precursors in the bone marrow of multiple myeloma

Precursors of plasma cells were studied in the bone marrow of 28 patients with multiple myeloma, plasma cell leukemia, and benign monoclonal gammopathy. Pre-B and B cell populations were analyzed with anti-B monoclonal antibodies corresponding to the clusters standardized at the Leucocyte Typing Workshops in Paris and Boston (CD9, CD10, CD19-22, CD24). In advanced forms of plasma cell malignancies, such as cases of multiple myeloma in stages II and III and of plasma cell leukemia, some cells of lymphoid morphology expressed common acute lymphoblastic leukemia antigen (CALLA, CD10) and HLA-DR, but contained no detectable terminal deoxynucleotidyl transferase enzyme. These CALLA+ cells were absent in benign monoclonal gammopathies. In multiple myeloma, the CALLA+ cells were negative for surface and cytoplasmic immunoglobulins (Ig), and, unlike CALLA+, terminal deoxynucleotidyl transferase (TdT+) pre-B cells in the normal bone marrow also failed to react with antibodies to B cell-associated antigens such as CD9, CD19, CD22, and CD24. The CALLA+, Ig- cells could be regarded as preplasmacytic since, after having been separated and stimulated with the phorbol ester 12-0-tetradecanoyl-phorbol-13 acetate in vitro, they transformed into plasma cells and synthesized the same heavy and light chains as myeloma cells.

Human B cell development. I. Phenotypic differences of B lymphocytes in the bone marrow and peripheral lymphoid tissue

The phenotype of B lineage cells (TdT+, pre-B, IgM+, IgD-, and IgM+,IgD+) in infant and adult human bone marrow was compared with that of B cells seen in peripheral tissues such as tonsil and blood. The range of B cell-associated antibodies used included four reagents with greater than 90% reactivity on peripheral B cells: RFB4 and To15 (both p135, corresponding to CD22), RFB6 (p140 corresponding to CD21), and Y29/55, a unique B cell-specific antibody. In addition, AL-1, an antibody with virtually no reactivity against peripheral B cells was also used. The BM cell subpopulations were heterogeneous in respect of antibody reactivity. The TdT+, pre-B and IgM+, IgD- cells were AL-1+ but did not express membrane antigens recognized by the antibodies To15, RFB4 (CD22), and RFB6 (CD21). TdT+, pre-B cells, and 50% of IgM+, IgD- BM B cells were also unreactive with antibody Y29/55, the other 50% being Y29/55+. In contrast, the IgM+,IgD+ BM B cells, like peripheral B cells, were positive with antibodies To15, RFB4, RFB6, and Y29/55, but reacted only in small numbers with AL-1. The orderly differentiation-linked display of these antigens was also suggested by the findings that normal TdT+, pre-B, and IgM+,IgD- cells expressed the To15 and RFB4 (CD22) antigens in their cytoplasm (in the Golgi region). This observation was confirmed in malignant common acute lymphoblastic and pre-B blast cells, as well as in the corresponding permanent cell lines KM3 and NALM-6. In these lines the membrane expression of To15 and RFB4 could be induced by phorbol ester during a 48 to 72 hr culture period.

Human B cell development. I. Phenotypic differences of B lymphocytes in the bone marrow and peripheral lymphoid tissue

The phenotype of B lineage cells (TdT+, pre-B, IgM+, IgD-, and IgM+,IgD+) in infant and adult human bone marrow was compared with that of B cells seen in peripheral tissues such as tonsil and blood. The range of B cell-associated antibodies used included four reagents with greater than 90% reactivity on peripheral B cells: RFB4 and To15 (both p135, corresponding to CD22), RFB6 (p140 corresponding to CD21), and Y29/55, a unique B cell-specific antibody. In addition, AL-1, an antibody with virtually no reactivity against peripheral B cells was also used. The BM cell subpopulations were heterogeneous in respect of antibody reactivity. The TdT+, pre-B and IgM+, IgD- cells were AL-1+ but did not express membrane antigens recognized by the antibodies To15, RFB4 (CD22), and RFB6 (CD21). TdT+, pre-B cells, and 50% of IgM+, IgD- BM B cells were also unreactive with antibody Y29/55, the other 50% being Y29/55+. In contrast, the IgM+,IgD+ BM B cells, like peripheral B cells, were positive with antibodies To15, RFB4, RFB6, and Y29/55, but reacted only in small numbers with AL-1. The orderly differentiation-linked display of these antigens was also suggested by the findings that normal TdT+, pre-B, and IgM+,IgD- cells expressed the To15 and RFB4 (CD22) antigens in their cytoplasm (in the Golgi region). This observation was confirmed in malignant common acute lymphoblastic and pre-B blast cells, as well as in the corresponding permanent cell lines KM3 and NALM-6. In these lines the membrane expression of To15 and RFB4 could be induced by phorbol ester during a 48 to 72 hr culture period.

A novel monoclonal antibody BI-3C5 recognises myeloblasts and non-B non-T lymphoblasts in acute leukaemias and CGL blast crises, and reacts with immature cells in normal bone marrow

A MCA raised against the human acute myelogenous leukaemia cell line KG1 reacted with only KG1 among 26 haematopoietic cell lines covering the major lineages. It reacted with early myeloid (M1/2), 1 of 2 acute myelomonocytic (M4) and most non-B non-T leukaemias, including blast crises of CGL. Among M1-AML cells, both MPO+ and MPO- blasts were BI-3C5+. Blasts in 3 Tdt+ M1-AMLs were simultaneously BI-3C5+. BI-3C5 reacted with 4% cells in normal BM, many of which were histologically recognisable as myeloid precursors. 8-15% of BI-3C5+ cells in BM were simultaneously Tdt+, and all were weakly Ia antigen+. BI-3C5 was unreactive with all peripheral leucocytes, with M3 and M5 AMLs, with lymphoid and myeloid leukaemias of "mature" phenotype (T-ALL, B-ALL, CLL, CGL) and with non-haematopoietic cell lines. BI-3C5 precipitated a 120K moiety from 125I-labelled KG1 membranes. It was not blocked by J5 anti-cALLA. The potential use of BI-3C5 in the classification of acute leukaemias is discussed.

A possible pathogenetic role of cationic proteins (CP) released by stored granulocytes in the development of pulmonary infiltrates after granulocyte transfusions

The cationic protein (CP) content of polymorphonuclear neutrophils (PMN) prepared for transfusion is depleted after storage. The supernatants from these PMN have in vitro a PMN aggregating activity which is abolished by the preabsorption with a specific rabbit anti-human PMN CP serum. Furthermore, when the supernatants stored for few hours were injected into New Zealand White rabbits, a marked sequestration of PMN took place in the lung microvascular bed. It is suggested that PMN storage per se can cause the release of intracellular mediators of possible pathogenetic importance in the development of the pulmonary infiltrates observed after PMN transfusions.

Functional behaviour and immunological phenotype of circulating B lymphocytes in multiple myeloma. Studies with pokeweed mitogen

Peripheral blood B lymphocytes, depleted of adherent cells, from 10 patients with multiple myeloma were cultured in the presence of PWM with autologous or donor T lymphocytes. The results show that: (1) co-cultures with allogeneic T lymphocytes produced more plasma cells than those with autologous ones; (2) the kappa/lambda ratio overlapped the values obtained in normal controls, irrespective of the light chain produced by the neoplastic plasma cells and (3) the immunological phenotype of plasma cells obtained from PWM stimulated peripheral B cells (RFA2+, RFA3+, A10+) was clearly different from that one of myelomatous plasma cells (RFA2-, RFA3-, A10+). These data confirm the T cell imbalance already seen in myeloma patients; moreover they show that PWM responsive B cell are functionally normal and phenotypically different from bone marrow myeloma cells. These results support the view that most of the peripheral B lymphocytes, previously identified as monoclonal are in fact normal cells bearing adherent monoclonal Ig molecules.

B-chronic lymphocytic leukaemia patients with stable benign disease show a distinctive membrane phenotype

The circulating B cells of 98 patients with B-CLL were analysed with a panel of conventional markers and monoclonal antibodies including RFA-1 and RFA-4. A subgroup of patients was defined with a distinctive double membrane marker phenotype (RFA-1+, RFA-4+). These patients showed features of clinical stability. Their physical signs, haematological features and lymphocyte counts remained unchanged for 5-10 years: therefore, the RFA-1+, RFA-4+ membrane phenotype appears to identify a subgroup of B-CLL patients with a particularly non-progressive disease.

Lineage relationship of chronic lymphocytic leukemia and hairy cell leukemia: studies with TPA

The tumor promoting agent TPA (phorbol ester; 1.6 X 10(-8)M) was used to induce the differentiation in vitro of B-chronic lymphocytic leukemia (B-CLL) cells from 14 untreated patients. The uninduced phenotype was SIg+, Mrbc+, RFT-1+, RFA-4-, FMC7-. After 72 h incubation with TPA, B-CLL cells became RFA-4+, FMC7+ and lost the capability of Mrbc rosetting. Large proportions of the "induced" cells also showed morphological and ultrastructural changes, such as undulating membranes and bleblike protusions and became strongly positive for tartrate resistant acid phosphatase (TRAP+) and also contained cytoplasmic immunoglobulins. These features are very similar to the features of hairy cell leukemia (HCL). These observations confirm previous clinical findings that B-CLL and HCL are related disorders of the B lineage. The development of "hairy" features in induced B-CLL and in HCL seems to be a malignancy-associated feature because the Mrbc+ normal B cells (B-CLL-equivalent cells) isolated from tonsil also develop TRAP positivity but no membrane aberrations.

Relevance of monoclonal antibodies in the diagnosis of unusual T-cell acute lymphoblastic leukaemia

3 cases of adult acute lymphoblastic leukaemia (ALL), the T-cell nature of which was identified only using a panel of monoclonal antibodies (MoAb), are described. All cases were E-rosette negative, surface immunoglobulin (SmIg) negative, common ALL (CALLA) antigen negative, terminal deoxynucleotidyl transferase (TdT) positive, and acid phosphatase positive. The T-cell origin of the blasts was demonstrated by the positivity with RFA-1, a MoAb which detects an antigen of MW 65-69000 present on the membrane of thymocytes and mature T-lymphocytes. In addition, 2 of the 3 cases were positive with OKT6, which recognizes cortical thymocytes. MoAb directed against more mature T lineage cells (OKT3, OKT4, OKT8, OKT11A) were consistently negative (less than or equal to 12%). These findings indicate that the use of a combination of MoAb is important in detecting individual cases of T-ALL, which otherwise might be classified as undifferentiated acute leukaemia or null-ALL. MoAb detecting a T-cell antigenic determinant of MW 65-69000 (e.g. RFA-1, OKT1, Leu1) appear the most specific reagents for T-ALL.

Immune-complexes (IC) in idiopathic neutropenia

The presence of immune-complexes (IC) and antipolymorphonuclear neutrophil (PMN) autoantibodies was investigated in 28 patients with chronic idiopathic neutropenia and normal or hypercellular bone marrow, 19 with a metamyelocyte arrest and 9 with more dysplastic features. The in vivo interaction between IC and PMN membrane receptors was evaluated by means of the PMN immunohistological technique. Circulating IC was evaluated with the C1q and rheumatoid factor agglutination inhibition techniques. An anti-PM autoantibody activity was investigated by challenging Fab obtained from the sera of 22 patients with PMN from normal donors. IC were detected in a high percentage of patients; in no case could an anti-PM autoantibody activity be seen. Most patients with a metamyelocyte arrest, but only 1 with more dysplastic features, were IC+. During a follow-up period of l2-52 months, none of the patients with a metamyelocyte arrest (IC+) developed anaemia, thrombocytopenia or leukaemia, while anaemia and thrombocytopenia were almost the rule in the clinical course of dysplastic bone marrow IC- patients: 2 of them developed acute myeloblastic leukaemia.

Idiopathic myelofibrosis: a possible role for immune-complexes in the pathogenesis of bone marrow fibrosis

Sixteen patients with idiopathic myelofibrosis (IM) have been investigated with respect to the possibility that immune mechanisms may be of importance in the pathogenesis of bone marrow fibrosis. The following points appear relevant: (1) immune-complexes (IC) are detectable with different techniques in a high percentage of patients with IM. Their presence is associated with evidence of bone-marrow histological markers of immune activity. (2) IgG is the main Ig class in the composition of IM IC. The results obtained favour the hypothesis that autoimmune mechanisms are involved in IM patients.