Natural killer function following allogeneic bone marrow transplantation. Very early reemergence but strong dependence of cytomegalovirus infection

Natural killer (NK) cell function was followed sequentially after allogeneic bone marrow transplantation (BMT) using three approaches: (1) chromium-release assay with purified mononuclear effector cells, (2) chromium-release assay with whole blood effectors, and 3) enumeration of lymphocytes bearing the NK-associated antigen NKH-1 (N901). The two latter methods enabled us to demonstrate a very early reappearance (at day 4 posttransplant) of pre-NK cells, which after interferon-alpha enhancement effectively lysed K562 cells and carried the NKH-1 antigen. During the first month NK function steadily increased, and at day 28 activated NK cells, which lysed the otherwise resistant P815 cell line, could be demonstrated concomittant with a substantial over-shoot in the proportion of NKH-1+ cells. Furthermore, the increase in NK lysis was more pronounced in patients with cytomegalovirus (CMV) infections (primary or reactivated). In contrast, the presence of graft-versus-host (GVH) disease did not associate with consistent changes in the NK parameters measured here. After the first month of increase, NK declined reaching levels near those observed in their respective bone marrow donors at day 90. These data demonstrate a surprisingly early recovery after allogeneic BMT, which can largely be related to external factors among which CMV seems to be a prime candidate.

First-line diagnosis based on immunological phenotyping in suspected acute leukemia: a prospective study

In a prospective analysis of the diagnostic value of immunophenotyping in acute leukemias (ALs), all patients admitted to a pediatric and a haematological department suspected of AL were examined consecutively with a selected panel of monoclonal antibodies (Mabs) against leucocyte differentiation antigens during an 8-month period. A total of 189 samples obtained from blood, bone marrow, spinal fluid and lymph nodes in 120 cases were all analysed blindly. The results were correlated with a routine morphological/cytochemical evaluation. Differing results were obtained in seven out of 38 cases in which the immunologically defined diagnosis was acute myeloid leukemia (AML), and in one out of 21 cases with the primary diagnosis acute lymphoid leukemia (ALL). Immunological phenotyping disclosed two cases of hybrid leukemia, one case of biphenotypic and one case of bilineal leukemia. No evidence of malignancy was found in 36 cases, 30 cases of blood and bone marrow and six cases of spinal fluids, in every case in accordance with the pathological examination. These results demonstrate that a first-line immunological evaluation of bone marrow, blood and spinal fluid from patients suspected of AL is highly capable of discriminating between different malignant and nonmalignant haematological diseases and also between various types of leukemias. The immunological methods do, however, require a sufficient amount of material which was a limiting factor in 14 out of 120 examinations, mainly from patients treated with several cycles of cytostatics. It is concluded that immunophenotyping can be used as a first-line diagnostic tool in malignant haematological diseases.

A two-color flow cytometry assay for detection of hairy cells using monoclonal antibodies

We have developed a simple two-color immunofluorescence assay equally suited for microscopy and flow cytometry detecting hairy cells (HCs) in single cell suspensions, based on the concomitant reactivities with the B cell-specific monoclonal antibody B1 (CD20) and the monocyte/HC-associated antibody SHCL-3 (CD11c). Thus, HCs can be demonstrated in peripheral blood, bone marrow, and spleen specimens from hairy cell leukemia (HCL) patients even when they constitute less than 1% of the cell suspension. Likewise, admixture experiments with normal mononuclear cells and the MOLT-4 T-acute lymphocytic leukemia (ALL) cell line demonstrated that HCs could be detected in amounts as low as 1%. The validity of this assay has been ascertained by the lack of double marker positivity in cell suspensions from B-chronic lymphocytic leukemia (CLL) and acute myelogenous leukemia (AML) patients that only expressed B1 or SHCL-3, respectively. Furthermore, other malignant blood diseases, including malignant lymphomas, acute leukemias, and chronic leukemias disclosed no double marker positive cells. In a clinical setting, this assay was used for purifying HCs (by flow cytometry) from the peripheral blood from patients with no apparent morphological evidence of circulating HC infiltration and for monitoring the effect of interferon therapy. In conclusion, this assay should be of value for both diagnosis and monitoring patients with HCL.

Identification and cloning of a prethymic precursor T lymphocyte from a population of common acute lymphoblastic leukemia antigen (CALLA)-positive fetal bone marrow cells

We have cloned common acute lymphoblastic leukemia (CALLA)-positive cells from human fetal bone marrow containing less than 1 in 10,000 E-RFC in round-bottomed microtiter wells (one cell per well) using the autocloning unit of an EPICS-V cell sorter. Expansion of such cells (with IL-2 and heavily irradiated autologous thymocytes as feeder cells) resulted in growth in 6-14% of the wells (mean, 11%) with cells with mature T lymphocyte phenotype. Two-color fluorescence analysis of outgrowing cultures furthermore ascertained that these cells had differentiated through a phase of simultaneous expression of T4 and T8 antigens and at the same time expression of the thymocyte-associated T6 antigens. Thus, given the fact that 10-20% of T cell acute lymphoblastic leukemia (T-ALLs) are CALLA+, we have been able to identify a human prethymic T lymphocyte population that might be the normal counterpart of precursor cell to the CALLA+ T-ALL cell.

Analysis of leucocyte differentiation antigens in blood and bone marrow from patients with Waldenström's macroglobulinaemia

Peripheral blood and bone marrow mononuclear cells from 10 patients with newly diagnosed Waldenström's macroglobulinaemia were analysed for the presence of leucocyte differentiation antigens using flow cytometry. Most patients had circulating intracytoplasmic-mu cells that were positive for the B-cell specific antigens B1, B2 and B4 and for the plasma cell antigen PCA-1. When such monoclonal cyto-mu + cells were purified by immune rosette depletion they were shown to express B1 to a much lesser extent than B2, B4 and PCA-1. In bone marrow samples cells with a similar phenotype, but with higher B1 expression were found in all patients. When the serum IgM paraprotein concentrations were compared to surface markers longitudinally from presentation and during the first courses of chemotherapy, a decreased serum IgM level was accompanied by a decrease in B1 cells in peripheral blood. These data demonstrate that WM cells possess a unique phenotype with coexpression of B-cell and plasma cell associated antigens.

13-cis retinoic acid treatment of myelodysplastic syndromes

Of eight patients with primary myelodysplastic syndrome (MDS) treated with Roacutane (13-cis retinoic acid, Roche, Basel, (13-RA)) 20 mg/m2 for 6 weeks and an additional 100 mg/m2 for 4 weeks (3 patients), 4 responded either with a slight increase in peripheral blood neutrophil count or a decrease in myeloperoxidase deficient neutrophils. In agar cultures 2 patients showed a concurrent increase in growth of day 11 colonies and clusters. In 2 of the patients a decrease in the number of immature bone marrow cells positive for the myeloid antibody anti-My7 was observed. Only minor alterations were seen in natural killer cell activity. In 4 patients showing clonal chromosomal abnormalities before treatment a disappearance of minor clonal abnormalities during treatment was observed, and in 3 chromosomal abnormalities reappeared after cessation of therapy. Even though the overall impact of 13-RA on the hematopoietic system was minor, the increase in myeloperoxidase normal granulocytes in the blood and the decrease in My7 positive cells and in clonal chromosomal abnormalities warrants further interest in this agent as a treatment modality in MDS. The side effects, especially experienced by the patients receiving 100 mg/m2, were, in spite of symptomatic treatment, of such a degree that only low dose treatment (10-20 mg/m2) administered for prolonged periods of time (3-6 months) would seem recommendable.

Secretory products from thrombin-stimulated human platelets exert an inhibitory effect on NK-cytotoxic activity

We have investigated the interaction between human platelets and the NK-system, with special emphasis on the action of secretory products from platelets in an NK assay with 51Cr-labelled K562 as target cells. Supernatants from thrombin-stimulated platelets added to the NK assay consistently decreased the NK-cytotoxicity by 40% +/- 4.3%, indicating the existence of secreted products from platelets as a source of NK-inhibiting substances. In contrast, no direct cytotoxic effect of these secretory products on the target cells (K562) was seen. Thus, normal human platelets, when stimulated with thrombin, are capable of secreting different, yet undefined factors, which significantly inhibit NK activity in vitro. The results also suggest that the role of products from contaminating in vitro activated platelets should be borne in mind when performing conventional NK assays.

Analysis of leukocyte differentiation antigens in blood and bone marrow from preleukemia (refractory anemia) patients using monoclonal antibodies

Peripheral blood and bone marrow mononuclear cells from patients with refractory anemia (RA) or RA with sideroblasts (defined according to the revised French-American-British classification with less than 5% blast cells in the bone marrow) were analyzed using a panel of monoclonal antibodies directed against leukocyte antigens on B lymphocytes, T lymphocytes, monocytes, and myeloid cells. In the peripheral blood an increased proportion of T lymphocytes (and correspondingly a decreased proportion of B cells) could be demonstrated. However, when expressed in terms of absolute numbers, the T cell component was depressed because of severely decreased numbers of T4+ helper cells. In contrast, the absolute numbers of T8+ suppressor cells were either normal or increased in the majority of the patients. This resulted in markedly decreased ratios of T4+/T8+ cells, which were closely correlated to the number of transfusions given to the patients because of their refractory anemia. Finally, nearly all of the patients exhibited decreased numbers of cells reactive with the N901 natural killer (NK) antibody, thus explaining our earlier finding of decreased NK activity in these patients. In the bone marrow increased proportions of myeloid cells reactive with monoclonal antibodies present on immature myeloid cells (My7 and My9) were found, suggesting the presence of malignant clones. Indeed, when the numbers of My7+ cells and the morphologic evaluations of bone marrow smears at the time of diagnosis were compared to the progression of the disease, a group of patients with high numbers of My7+ cells and normal morphology could be identified that had a high probability of progression to refractory anemia with an excess of blasts or to overt acute myeloid leukemia. Thus, the use of antibodies defining leukocyte differentiation antigens might be of significant value in the diagnosis and prognostication of the myelodysplastic syndromes. These findings are discussed in relation to the pathogenesis of this potentially premalignant condition with special emphasis on possible defects in the immunologic defense mechanisms against early neoplasias.

Prognostic significance of some clinical, morphological and cytogenetic findings in refractory anaemia (RA) and RA with sideroblasts

In 27 patients initially diagnosed as refractory anaemia (RA) or RA with sideroblasts (RA-S) according to the FAB-classification a number of clinical, morphological and cytogenetic parameters were correlated for prognostic significance. From these correlations it emerged that severe cytopenia is centrally positioned with regard to clinical course in RA and RA-S. Positive correlations were found to initial diagnosis, clonal cytogenetic abnormalities, progression to RA with an excess of blasts (RAEB) or acute myeloid leukaemia (AML), the percentage of bone marrow blast cells and prolonged half life for radioactively labeled iron. The degree of peripheral blood granulocytopenia, alone, was correlated to bone marrow hypoplasia. Moreover, the frequency of abnormal karyotypes was inversely correlated to bone marrow cellularity and proportional to the frequency of bone marrow blast cells. From these relationships it may be proposed that chromosome abnormalities are associated with prolonged blast cell generation times and inhibition of blast cell maturation resulting in reduced marrow cellularity and blast cell accumulation, and, in the peripheral blood, falling percentages of neutrophil granulocytes. With the blast cell accumulation the bone marrow cellularity again becomes hyperplastic and the preleukaemic condition is transformed into RAEB or AML.

Orderly expression of B cell antigens during the in vitro differentiation of nonmalignant human pre-B cells

Early human pre-B cells were isolated from fetal bone marrow and induced to differentiate in vitro under the stimulus of phorbol myristic acid or leukocyte-conditioned medium during a 48-hr culture period. Tritiated thymidine culture experiments substantiated that changes in surface marker phenotypes were not the results of outgrowth of subsets responsive to these stimuli. Interestingly, the addition of monoclonal antibodies directed against CALLA resulted in neither proliferation nor differentiation of the fetal lymphoid progenitor cells. Distinct changes in cell surface phenotypes were observed without evidence of cellular enrichment or depletion. The number of CALLA- and TdT-positive cells decreased, whereas the number of B1- and sIgM-positive cells increased. Moreover, a small number of pre-B cells could be driven to a more mature phenotype with the appearance of B2 and sIgG. In contrast, the pan-B B4 antigen did not alter significantly. These changes were even more pronounced when both induction stimuli were present. These studies, and previous studies on the subsets and differentiation of non-T cell acute lymphoblastic leukemias, suggest an orderly acquisition of B cell antigens during the stages of pre-B cell differentiation in man.

Orderly expression of B cell antigens during the in vitro differentiation of nonmalignant human pre-B cells

Early human pre-B cells were isolated from fetal bone marrow and induced to differentiate in vitro under the stimulus of phorbol myristic acid or leukocyte-conditioned medium during a 48-hr culture period. Tritiated thymidine culture experiments substantiated that changes in surface marker phenotypes were not the results of outgrowth of subsets responsive to these stimuli. Interestingly, the addition of monoclonal antibodies directed against CALLA resulted in neither proliferation nor differentiation of the fetal lymphoid progenitor cells. Distinct changes in cell surface phenotypes were observed without evidence of cellular enrichment or depletion. The number of CALLA- and TdT-positive cells decreased, whereas the number of B1- and sIgM-positive cells increased. Moreover, a small number of pre-B cells could be driven to a more mature phenotype with the appearance of B2 and sIgG. In contrast, the pan-B B4 antigen did not alter significantly. These changes were even more pronounced when both induction stimuli were present. These studies, and previous studies on the subsets and differentiation of non-T cell acute lymphoblastic leukemias, suggest an orderly acquisition of B cell antigens during the stages of pre-B cell differentiation in man.

Immunomodulation of NK and ADCC by Corynebacterium parvum in acute myeloid leukaemia patients

Natural killer (NK)- and antibody dependent cellular cytotoxicity assays were performed using cryopreserved effector cells in AML patients receiving i.c. and s.c. injections of Corynebacterium parvum. A dose related increase in NK could be demonstrated with peaks in NK at day 1 with full Cp dosage and at day 14 with 50% doses. This increase was attributable to the Cp vaccine since normal donors receiving tetanus toxoid or pneumococcal polysaccharide and AML patients randomized not to receive Cp did not show similar NK boosting. The increase was probably due to interferon induction in vivo and could be demonstrated with purified T- and non-T-lymphocyte subsets. However, longitudinal measurements showed that the ability of Cp to boost NK was gradually lost over 4-6 months. ADCC studies showed that while lymphocyte-ADCC was not consistently affected by Cp, monocyte-ADCC was enhanced with maximal cytotoxicity at day 14.

Breast tumour as a first manifestation of extramedullary relapse in acute lymphoblastic leukaemia

After 2 years of maintained complete remission, a 17-year old girl suffering from common acute lymphoblastic leukaemia (C-ALL) developed a mass in the right breast. Determination of the tumour cell phenotype using a panel of monoclonal antibodies demonstrated the presence of leukaemic blasts. At this stage no other sign of relapse could be demonstrated. Later, however, when the leukaemia progressed despite aggressive treatment, blasts with the same surface phenotype as the ones in the breast were obtained both from repeated biopsies from a mediastinal mass and from a lower abdominal mass. Manifestation of first relapse in ALL presenting as a breast tumour has never been described before and may be added to other unusual extramedullary sites of relapse. The significance of immunologically defined phenotyping of cells from tissue biopsies is underlined.

Purification of common acute lymphoblastic leukemia antigen positive cells from normal human bone marrow

Mononuclear cells expressing the common acute lymphoblastic leukemia antigen (CALLA) were purified from normal adult human bone marrow, where they constitute a small fraction of the total population. This was accomplished by a two-step purification from Ficoll-Hypaque-isolated mononuclear cells. Isolated mononuclear cells were first labeled with a mixture of monoclonal antibodies (MoAb) specific for myeloid and erythroid precursor cells, and immune rosettes were then formed with sheep erythrocytes coated with rabbit anti-mouse antibodies (R/M-SRBC). Sedimentation through Ficoll-Hypaque then eliminated the majority of mature myeloid cells. The second step consisted of labeling the remaining rosette-negative cells with CALLA-specific MoAb and purifying CALLA+ cells by fluorescence activated cell sorting. Alternatively, CALLA+ cells were purified in a second R/M-SRBC rosette sedimentation step. The purified CALLA+ cells, which morphologically were medium to large lymphoid cells, were subsequently studied using dual fluorescence techniques to identify surface markers as well as intracytoplasmic staining to detect terminal deoxynucleotidyl transferase enzyme (TdT) and intracytoplasmic mu. While the CALLA+ cell suspensions contained very few mature myeloid cells or T lymphocytes, the finding that 5% to 11% of them were cyto-mu+ and 13% to 22% expressed the B1 differentiation antigen clearly indicated that at least some of these cells were B cell precursors. Because 48% to 63% of the cells were TdT+ and practically all of them expressed Ia antigen, it appears that these cells are a mixture of very early lymphoid precursor cells as well as more differentiated pre-B cells. The phenotype of these normal cells is very similar to that of common ALL cells. Differences in the surface marker phenotypes between adult and fetal CALLA+ cells that have previously been purified were also identified.

Acid phosphatase and acid esterase activity in neoplastic and non-neoplastic lymphoid cells. A semiquantitative evaluation related to immunological markers in 112 cases

Acid phosphatase (AcP) and acid alpha-naphthylacetate esterase (ANAE) were examined in lymphoid cells from 104 patients suffering from various lymphoproliferative disorders and from 8 healthy controls. Enzyme activities were evaluated by means of a scoring system. Scores of AcP and ANAE were higher in normal T cells than non-T cells. In comparison, the activated T cells in infectious mononucleosis showed increased AcP and decreased ANAE reaction. Malignant T lymphoblasts had a distinct granular AcP positivity in contrast to the faint reactivity observed in cALL blasts, whereas ANAE showed negative or weak reaction in both subsets. High scores and distinct staining patterns for both enzymes were found in T CLL and T prolymphocytic leukaemia, clearly different from the weak activities seen in B CLL, B PLL and some B cell lymphomas. The latter, too, could be distinguished by mutual differences in enzyme reactions. High AcP and ANAE scores were also found in hairy cell leukaemia, and the staining patterns together with the tartrate resistance firmly established the diagnosis. Thus, simultaneous determinations of AcP and ANAE can be of great value in the diagnosis of lymphoid malignancies.

Effect of recombinant alpha interferon on NK and ADCC function in lung cancer patients: results from a phase II trial

During a phase II trial of recombinant IFN-alpha given in doses of 50 X 10(6) units/m2 three times per week to lung cancer patients, 13 patients were evaluated longitudinally in NK and ADCC assays and in immunofluorescence tests enumerating the number of cells reactive with the new N901 NK-cell antibody. An increase in NK-cell activity could be demonstrated when values before and 24 h after the first injection of IFN were compared, but simultaneously the enhancing effect of IFN-alpha on NK-cells added to in vitro cultures was abolished, probably as a result of preactivation of NK cells in vivo. After 2-4 weeks of treatment, the majority of patients exhibited a pronounced decrease in NK-cell activity while still retaining the inability to be boosted by IFN added in vitro. Investigations with the NK antibody N901 showed that the initial increase in NK activity appeared concomitantly with an increase in the number of N901 positive cells, indicating that the mechanism behind this increase was an increase in the number of circulating NK cells. In contrast, the decrease in NK activity mentioned above was not followed by a similar decrease in the number of N901+ cells, and it was concluded that this decrease might be attributable to either an exhaustion phenomenon or to an induction of a refractory state of peripheral blood NK cells. When measuring ADCC activity, increases in lytic activity were seen only in patients in whom they could be attributed to non-IgG-dependent (NK-like) mechanisms. These data are discussed in relation to other clinical trials using leukocyte or recombinant IFN-alpha.

Natural killer (NK)-cell activity and antibody-dependent cellular cytotoxicity (ADCC) in primary preleukemic syndrome

In 13 patients with a multi-parameter based diagnosis of primary acquired preleukemic syndrome (PPS), natural killer (NK) cell activity and antibody-dependent cellular cytotoxicity (ADCC) were investigated on peripheral blood mononuclear cell (MNC) fractions. In all but two patients a defective NK activity was found. Lymphocyte-monocyte mixture experiments demonstrated that this was not due to suppressor monocytes. Furthermore, NK activity was defective when both myeloid and non-myeloid target cell lines were used. Addition of human leukocyte interferon to the NK cultures augmented the cytotoxicity, which exhibited the same kinetics as that of normal controls, but NK activity levels remained subnormal. These data strongly indicate that the decreased NK activity seen in the patients is due to a decreased number of circulating NK cells. In contrast ADCC was within the normal range both when MNC suspensions as well as when purified peripheral blood lymphocytes were used as effector cells thus ruling out subnormal lymphocyte ADCC masked by the presence of monocyte ADCC. These results demonstrate that PPS patients have a selective NK defect with an intact lymphocyte ADCC function. Whether this defect will prove to be valuable in the assessment of a malignant transformation in a given patient will await further longitudinal NK studies and clinical follow-up of the patients.

Selective effects of alpha interferon on human T-lymphocyte subsets during mixed lymphocyte cultures

Mixed lymphocyte reaction (MLR) cultures of human lymphocyte subsets with or without the addition of physiological doses of human alpha interferon (IFN-alpha) were compared with respect to surface marker phenotypes and proliferative capacities of the responder cells. A selective depression on the T4 (inducer) T-cell subset could be demonstrated as a sequence of events: decreased fluorescence intensity of the T4 inducer cells (day 2 of culture), decreased percentages of T4 cells as demonstrated by cell cytofluorometry (days 3-6 of culture), and decreased 3H-thymidine incorporation of purified T4 cells and decreased numbers of T4 cells harvested from IFN MLRs (days 5-6 of culture). In contrast, it was shown that the T8 (cytotoxic/suppressor) subset in MLRs was either not affected or slightly stimulated by the addition of IFN. The depression of the T4 cells by IFN was accompanied by a decrease in the number of activated T cells expressing Ia antigens. On the other hand, IFN MLRs contained greater numbers of cells expressing the T10 differentiation antigen. In experiments with purified T-cell subsets the IFN effect was exerted directly on the T4 cells and not mediated by either T8 suppressor cells or monocytes. These findings are discussed in relation to other immunoregulatory effects of IFN-alpha.

Purification and characterization of fetal hematopoietic cells that express the common acute lymphoblastic leukemia antigen (CALLA)

Fetal hematopoietic cells that express the common acute lymphoblastic leukemia antigen (CALLA) were purified from both fetal liver and fetal bone marrow by immune rosetting with sheep erythrocytes coated with rabbit anti-mouse immunoglobulin and by fluorescence-activated cell sorting. Dual fluorescence techniques disclosed that these cells were heterogenous with respect to the expression of a series of differentiation and activation antigens defined by monoclonal antibodies. Thus, whereas all CALLA+ cells were Ia+ and expressed two activation antigens, J2 and T10, only 30-50% expressed B1 antigen. Furthermore, using methanol-fixed cells, it could be shown that approximately 20% contained intracytoplasmic mu chains (cyto-mu) and that approximately 15% were positive for the terminal transferase enzyme (TdT) marker. The CALLA+ fetal cells thus closely resemble the childhood acute lymphoblastic leukemia cell with respect to surface marker phenotype. A population of CALLA- cells devoid of mature erythroid and myeloid surface markers was found to contain higher numbers of TdT+ cells but lower numbers of cyto-mu, B1, and Ia+ cells than the CALLA+ subset. In vitro analysis of normal, purified CALLA+ cells demonstrated that incubation at 37 degrees C with J5 monoclonal antibody specific for CALLA resulted in the specific modulation of surface antigen. Similar results have previously been obtained with CALLA+ tumor cells. Although phenotypic analysis of CALLA+ cells suggests that these cells are relatively immature lymphoid cells, CALLA+ cells do not appear to contain either myeloid precursor cells (CFU-G/M) or the earliest lymphoid stem cells.

Interferon-induced changes in expression of antigens defined by monoclonal antibodies on malignant and nonmalignant mononuclear hematopoietic cells

The effect of alpha interferon (alpha IFN) on the expression of histocompatibility--as well as differentiation antigens on normal and malignant hematopoietic mononuclear cells--were investigated by cell cytofluorometry using a panel of monoclonal antibodies (MoAbs). An increase in the expression of HLA-antigens detected by beta 2-Microglobulin (beta 2-M) could be demonstrated for peripheral blood mononuclear cells, non-T cells, Null cells, activated T cells, fetal thymocytes, adherent cells, and on four malignant non-T lymphoblastoid cell lines. In contrast, no significant differences were observed in the expression of antigens specific for B-lymphocytes (B1), T-lymphocytes (T3, T4, T6, T8, T11), NK-cells (901) and adherent cells (Mo1-4). Likewise, the expression of Ia-antigens remained unaltered on non-T cells, Null cells, and monocytes. The only other effect of IFN was an increase in the number as well as the amount of lymphocytes expressing the T10 antigen. It thus seems that the enhancing effect of IFN on resting cells of the immune system is highly selective. On the four lymphoblastoid cell lines, the expression of the common acute lymphoblastic leukemia antigen (CALLA) was significantly decreased concomitantly with the increase in MHC-antigens. On the other hand, the density of both a HLA-D related Ia antigen (I2) and a B-lymphocyte differentiation antigen (B1) remained unaltered following IFN treatment. The implications of these findings are discussed.

Adjuvant immune stimulation with Corynebacterium parvum during maintenance chemotherapy of acute myeloid leukemia. A prospective randomized study

Of 93 consecutively treated patients with acute myeloid leukemia 36 (39%) achieved complete remission (CR). Thirty-five patients were randomized to receive either maintenance chemotherapy alone (C) or a combination of active nonspecific immunotherapy with Corynebacterium parvum and chemotherapy (C + I). Maintenance therapy was given monthly for 1 year or until relapse. The median survival time was 21 months for patients treated with chemotherapy alone, compared with 30 months for patients treated with chemotherapy and immunotherapy. The median remission duration was 15 months for patients treated with chemotherapy, compared with 18 months for chemotherapy and immunotherapy group. While no statistically significant difference in remission duration or survival time could be attributed to the use of immune stimulation, a plateau of 40% long-term time survivors was defined in the chemotherapy and immunotherapy group. Age and sex were found to be the major prognostic factors for achievement of CR. No difference was found in remission duration or survival between the two different induction schedules. Neither did the morphological subtype of AML (FAB classification) or the leukocyte count at diagnosis correlate with remission rate or survival.

Stereological analysis of the ultrastructure in isolated human T and non-T lymphoid cells. I. Description of method and data on normal blood lymphocytes

Stereological techniques were applied to isolated and purified normal human T and non-T lymphocytes from the peripheral blood, allowing a quantitative characterization of the average cell and its subcellular components in each population at the ultrastructural level. From electron micrographs taken at two levels of magnification and subjected to point counting procedures and measurements on a Kontron Videoplan analyser, absolute and relative data comprising volumes, surfaces and ratios were obtained. The stereological model proved efficient in establishing important differences between the two lymphocyte subsets regarding features generated from the whole cell as well as from the nuclear and cytoplasmic compartments. Thus the average T cell compared to the non-T cell possessed the following qualities: a smaller cell volume and cell surface area due to a smaller cytoplasmic volume and surface area; a lower nuclear euchromatin-heterochromatin volume ratio indicating a greater amount of heterochromatin in the nucleus; a smaller volume and surface area of rough ER, and (to a less extent) a smaller amount of Golgi apparatus, dense bodies and residual cytoplasm. The rare occurrence of parallel tubular arrays were seen in the non-T fraction only, and dense bodies were more often clustered in T cells. The differences are discussed in immunological and functional terms.

Ultrastructure of normal human blood T lymphocyte subsets isolated by cell sorting using monoclonal antibodies. A stereological analysis

In continuation of a previous study, the quantitative fine structural characteristics of the average normal human pan-T lymphocyte and its subsets in the peripheral blood has been established using stereological methods. T cell subpopulations were isolated and identified by means of monoclonal T3, T4 and T8 antibodies and a fluorescence-activated cell sorting machine. Comparative studies on ultrastructural morphology were made between the E-rosetting lymphocyte and the T3-positive cell, both markers of the pan-T cell, and between the functionally different T4- and T8-reactive subsets, defining the helper/inducer and suppressor/cytotoxic T cell subpopulation respectively. No significant differences were recorded between the E-rosetting and the T3+ lymphocyte except for minor deviations regarding the surface of the plasma membrane. In comparison with the T4+ lymphocyte, the T8+ cell showed a larger cell volume and cell surface area and decreased nucleo/cytoplasmic volume and surface ratios. The increase in cell size was the result of greater volumes of residual cytoplasm as well as of intracytoplasmic organelles, such as mitochondria, RER, Golgi apparatus and granules, whereas nuclear parameter estimates were concordant. The structural deviations between the T4+ and the T8+ subsets are discussed in the context of their different functional capacity as helper and suppressor/cytotoxic cells.

The relationship between human T-lymphocyte subsets defined by monoclonal antibodies and by avidity differences to sheep erythrocytes

By E-rosette sedimentation procedures and fluorescence activated cell sorting of monoclonal antibody-coated T lymphocytes, we have investigated the relationship between the human T lymphocyte subsets defined by the monoclonal antibodies against the T4 and T8 antigens and those defined by avidity differences to sheep erythrocytes. Through a correlation was demonstrated between the T4+ (inducer) cells and the high avidity ("active") T cells and between the T8+ (suppressor) cells and low avidity T cells, these subsets were far from identical, and it is concluded that the application of monoclonal antibodies represents another valuable and standardized approach for estimating T cell subsets.

Interferon enhances the antibody-dependent cellular cytotoxicity (ADCC) of human polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMN) from healthy volunteers were tested for ADCC activity against both erythrocyte and tumor targets with and without the addition of human leukocyte interferon (IFN). It was demonstrated that IFN within 30 to 60 min enhanced the reaction in a dose-dependent manner with minimal IFN doses ranging from 1 to 100 units. Formal proof that the augmenting agent was IFN was obtained by using pure IFN proteins in combination with both mock-IFN preparations, which showed no enhancing activity, and anti-IFN antisera, which inhibited the action of the completely purified IFN proteins. In the light of data demonstrating that the IFN effect was most pronounced when the IgG antibodies in the ADCC reaction were present in suboptimal amounts, it is hypothesized that IFN may play a special role in the early nonspecific immune response against non-self antigens.

Interferon enhances the antibody-dependent cellular cytotoxicity (ADCC) of human polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMN) from healthy volunteers were tested for ADCC activity against both erythrocyte and tumor targets with and without the addition of human leukocyte interferon (IFN). It was demonstrated that IFN within 30 to 60 min enhanced the reaction in a dose-dependent manner with minimal IFN doses ranging from 1 to 100 units. Formal proof that the augmenting agent was IFN was obtained by using pure IFN proteins in combination with both mock-IFN preparations, which showed no enhancing activity, and anti-IFN antisera, which inhibited the action of the completely purified IFN proteins. In the light of data demonstrating that the IFN effect was most pronounced when the IgG antibodies in the ADCC reaction were present in suboptimal amounts, it is hypothesized that IFN may play a special role in the early nonspecific immune response against non-self antigens.

Subclassification in acute lymphoblastic leukaemia: acid phosphatase reaction and immunological markers in relation to clinical features. A comparative study of 44 patients

A prospective, comparative study of cytochemical and immunological markers and clinical features was undertaken in 44 patients with ALL (children and adults). 12 patients (27%) had T-ALL, 1 patient (2%) B-ALL and 31 patients (71%) (non-T, non-B)-All. E-rosetting lymphoblasts ranged from 35 to 96% (median: 61), highest when AET-treated SRBC were used as indicator cells. All 12 E-rosette positive cases were strongly acid phosphatase (AcP)-positive, showing a homogeneous pattern of distinct granular AcP-activity in more than 85% of the lymphoblasts (median: 96%) significantly different from the median of 26% granulated blasts found in (non-T, non-B)-ALL cases. Counting blasts with granular AcP-activity proved to be both easier than using a scoring system for the AcP-reaction and more efficient in terms of discriminating ability between the subgroups. Significant clinical and haematological features characterizing the T- and AcP-positive cases included: (1) Predominance of young adult men, (2) presence of a mediastinal mass, (3) involvement of skin and serous membranes, (4) only slightly affected haemoglobin concentration at presentation, (5) difficulty in obtaining complete remission, (6) shorter duration of first complete remission and (7) shorter survival rate. It is confirmed that AcP-staining of lymphoblasts is an easy, reproducible and inexpensive method for identifying the T-cell variety of ALL.

Malignant monoblasts can function as effector cells in natural killer cell and antibody-dependent cellular cytotoxicity assays

This is the first report describing natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) of malignant monoblasts. Pure acute monoblastic leukemia was diagnosed in bone marrow aspirations from two patients by use of conventional cytochemical methods as well as multiple immunologic techniques including detection of ALL antigens and terminal transferase. The malignant cells were subsequently found to be potent effectors in NK and ADCC assays. Addition of partially purified alpha-interferon to the in vitro cultures was found to have an enhancing effect on NK activity, whereas no modulation was seen in ADCC. These findings are discussed in the light of our present knowledge of lymphoid NK cells.

Interferon-induced augmentation of cytotoxic killer cell generation in mixed lymphocyte cultures: analysis of the effector cell product

Alloreactive cytotoxic lymphocytes were generated during mixed lymphocyte cultures (MLC). Human leucocyte interferon added during MLC gave rise to a moderate inhibition of thymidine uptake, yet augmentation of the allospecific cytotoxic product generated was found. Effector cell activities after MLC in the presence and absence of interferon against autologous cells were negligible, whereas NK-sensitive targets and antibody-coated target cells were killed to a higher extent, comparably, by cells generated during MLC in the absence of interferon. Cell separation experiments and cold target inhibition experiments were performed and showed that the effector cells generated with and without interferon had similar characteristics and were distributed among the same lymphocyte subpopulations. The key conclusion was that the augmented cytotoxicity was caused by alloreactive T cells, most of which were F(c) gamma receptor-negative, and was not due to enhanced 'NK-like' or antibody-dependent cell-mediated cytotoxic activity induced by interferon.

Human lymphocyte and mouse erythrocyte rosettes. Optimization of the assay

Rosettes formed between lymphocytes and unsensitized mouse erythrocytes not only detect a subset of normal b-lymphocytes, but furthermore seem to be of considerable importance in the differential diagnosis of various B cell malignancies. From a series of experiments aimed at optimizing this rosette test, we conclude: (1) Erythrocytes from different mouse strains vary in their affinity for lymphocytes; (2) Experimental conditions are less strict when testing chronic lymphatic leukaemia lymphocytes than normal lymphocytes; (3) Treatment with the sulphydryl compound aminoethyl-isothiouronium bromide, which enhances sheep erythrocyte rosette formation, has an opposite effect on mouse rosettes, and (4) Neuraminidase treatment of the lymphocytes is not necessary when optimal experimental conditions are used.

Effects of basic proteins on spontaneous rosette formation between human lymphocytes and xenogeneic erythrocytes

Two basic proteins (methylated human serum albumin, MHSA, and protamine sulphate, PS) were investigated for their modulatory capacities on a panel of human lymphocyte surface markers. MHSA and PS enhanced the spontaneous rosettes with mouse, sheep and horse erythrocytes, but did not affect the number of rosettes with zymosan particles coated with human complement, or with sheep erythrocytes sensitized with rabbit anti-sheep IgG antibody. Whereas the standard sheep (E) rosette test was not influenced by the negatively charged glycoprotein ceruloplasmin, this compound could, however, abolish the MHSA- and PS-induced enhancements of the number of sheep rosettes. By double marker studies it was furthermore demonstrated that a subset of B cells was induced by MHSA to form E rosettes, and that the same agent increased the number of B cells forming mouse rosettes, so that nearly all B cells were made positive for this marker.

Effector cell potential of two human T-cell subpopulations with different affinities to sheep erythrocytes

Two human T lymphocyte subpopulations were purified on the basis of their different affinities to sheep erythrocytes and compared with unseparated and non-T lymphocytes as effectors in cell-mediated lympholysis (CML) after mixed lymphocyte culture (MCL), in antibody-dependent cellular cytotoxicity (ADCC) against the mouse mastocytoma line P 815, and in spontaneous cell-mediated cytotoxicity (SCMC) against the human myeloid leukaemia line K 562 and the Burkitt lymphoma line RAJI. The low-avidity T cells (T1) had developed into more potent effectors than the high-avidity (Te) when assessed in CML. In ADCC and SCMC both subsets exhibited low but consistent lysis with no demonstrable differences. Addition of human leucocyte interferon to the ADCC and SCMC cultures resulted in enhanced SCMC, most notable and to an equal extent with the T cell subsets. In contrast, ADCC of unseparated cells, non-T cells, and the two T subsets was found to be unchanged after interferon addition. These data are discussed in relation to findings with human T-cell subpopulations purified by other methods.

Immunomodulation by Corynebacterium parvum in normal humans

Four normal human donors were immunized with 2 mg of heat-killed Corynebacterium parvum by subcutaneous and intracutaneous injections, and lymphocyte surface markers, antibody-dependent (ADCC), and spontaneous cell-mediated (SCMC) cytotoxicities followed for a 28-day period. Although no changes were observed in the relative proportions of B, T, and Fc receptor-carrying lymphocytes, two T cell subpopulations, namely, the autologous rosette-forming cells and active rosette-forming cells, both exhibited significant increases. Significant increases were also demonstrated in the proportion of monocytes carrying Fc receptors and in the proportion of monocytes phagocytizing Latex beads. Although no consistent changes could be found in ADCC against the P 815 mastocytoma cell line, the SCMC against both the myeloid leukaemia line K 562 and the lymphoma line RAJI was found to be elevated as early as 6 hr post-vaccination. The possibility that the enhanced SCMC activity was induced in vivo by interferon was supported thus: 1) Enhancement of SCMC in vitro by interferon was abrogated by the vaccination. 2) Serum interferon determinations showed significant increases in parallel with the lack of in vitro SCMC enhancement.

Immunomodulation by Corynebacterium parvum in normal humans

Four normal human donors were immunized with 2 mg of heat-killed Corynebacterium parvum by subcutaneous and intracutaneous injections, and lymphocyte surface markers, antibody-dependent (ADCC), and spontaneous cell-mediated (SCMC) cytotoxicities followed for a 28-day period. Although no changes were observed in the relative proportions of B, T, and Fc receptor-carrying lymphocytes, two T cell subpopulations, namely, the autologous rosette-forming cells and active rosette-forming cells, both exhibited significant increases. Significant increases were also demonstrated in the proportion of monocytes carrying Fc receptors and in the proportion of monocytes phagocytizing Latex beads. Although no consistent changes could be found in ADCC against the P 815 mastocytoma cell line, the SCMC against both the myeloid leukaemia line K 562 and the lymphoma line RAJI was found to be elevated as early as 6 hr post-vaccination. The possibility that the enhanced SCMC activity was induced in vivo by interferon was supported thus: 1) Enhancement of SCMC in vitro by interferon was abrogated by the vaccination. 2) Serum interferon determinations showed significant increases in parallel with the lack of in vitro SCMC enhancement.

Analysis of the lymphocyte distribution during Isopaque-Ficoll isolation of mononuclear cells from human peripheral blood

Using chromium-labelled mononuclear cells the movements of lymphocytes in Isopaque-Ficoll (I-F) gradients were analysed. Even small percentages of ox or autologous human erythrocytes mixed with the lymphocytes caused a significant loss of lymphoid cells and this loss was augmented when higher numbers of red cells were added. Such losses could be prevented using I-F gradients of higher densities, but then neutrophils and erythrocytes were found to contaminate the mononuclear suspensions recovered. Purified B and T lymphocytes were found to move identically on the gradients, but when human erythrocytes were added to the lymphocyte suspensions to be separated, a small but significant preferential loss of T cells was observed.

The human mixed lymphocyte reaction responder and stimulator capacities of highly purified T- and non-T cells and the role of monocytes

E-rosette sedimentation with AET treated sheep red blood cells and human lymphocytes provieded a source of highly purified T- and non-T cells. Together with unseparated cells these were tested for responder and stimulator capacities in the mixed lymphocyte reaction, and it was found that the non-T cells were weak, but consistent responders only when T cells were present as stimulators. On the other hand, T-T combinations always exhibited weak proliferation demonstrating that T cells possess stimulator capacities. Adherent cells grown on Petri dishes were found to exert a dual function: as helper cells in low, and suppressor cells in high concentrations.

Functional characterization in vitro of two human T-cell subpopulations with different affinities to sheep erythrocytes

On the basis of their different abilities to form resettes with unsensitized sheep erythrocytes (SRBC), two subpopulations of human T lymphocytes were separated by the rosette sedimentation technique. In a series of in vitro experiments the T cells carrying high-avidity receptors for SRBC ('active' T cells) were shown to respond significantly better when stimulated with purified protein derivative (PPD) and allogeneic cells than the subpopulation carrying low-avidity receptors ('non-active' T cells). On the other hand, the latter responded better to phytohaemagglutinin, concanavalin A and pokeweed mitogen; it was likewise demonstrated that these cells were better stimulators in a mixed lymphocyte reaction. The role of monocytes in mitogen and PPD responses was investigated by adding such cells to Fe-treated suspensions. These were found to be crucial for an optimal response of both subpopulations. Furthermore, different patterns of activation were observed for the active and non-active cells. Especially interesting was the observation that the Con A response of the active fraction was more monocyte-dependent than that of the non-active one.

Two small lymphocyte subpopulations in human peripheral blood. I. Purification and surface marker profiles

By means of simple rosette sedimentation methods two subsets from human peripheral blood lymphocytes have been isolated: (1) (E, Fc)- and (2) (E, Ig)-. The first subset was obtained by centrifuging suspensions of macrophage-depleted PBL in which E and EA rosettes had been allowed to form simultaneously. The dominant marker of these E- Fc- cells was surface Ig, and during 4 days of culture this population did not alter its surface markers. Subset 2 was obtained in two ways following rosette centrifugation with AET-treated SRBC and rabbit anti-human Ig-coated autologous RBC. This 'Null cell population' was shown to be highly variable as judged by the surface markers applied after 4 days of culture, and it is suggested that Null cells contain a number of immature lymphoid cells that may acquire their surface marker during culture. It is concluded that the methods described for purification of small subsets of human lymphocytes are effective and easy to perform and might be used to purify cells for functional studies.