Quality assessment for immunophenotyping of leukaemias and lymphomas: the Dutch experience. The SIHON Study Group

Sending material at regular intervals to laboratories that perform immunophenotyping of leukaemias and lymphomas showed a large variety in the percentage of positive cells between the different laboratories but an agreement in diagnosis of more than 90%. Each laboratory used his own methods but antibody panels and guide-lines for interpretation were standardised. Studies are in progress to answer the question if standardisation in flow cytometry will result in more comparable results.

Characterization of Epstein-Barr viral strains in parotid gland saliva and peripheral blood of patients with primary Sjögren's syndrome and healthy EBV carriers

Increased Epstein-Barr virus (EBV) replication has been reported in the salivary and lacrimal glands in Sjögren's syndrome (SS). We studied whether or not certain EBV strains would occur preferentially in the peripheral blood and parotid gland saliva of 18 EBV-seropositive patients with primary Sjögren's syndrome (pSS) and 12 EBV-seropositive control persons. Transforming EBV was detected in the blood of 11 of 18 (61%) pSS patients and 9 of 12 controls (75%). Unexpectedly, neither transforming nor Raji-superinfecting EBV strains were detected in SS parotid saliva, whereas these EBV types were detected in control saliva in 7 and 8 cases, respectively (P < 0.001). Transforming EBV strains were further characterized by 'Ebno-typing,' i.e., analysis of the size spectrum of the viral antigens EBNA 1, 2, 3, and 6 in immunoblots of lymphoblastoid cell lines (LCL). Previous work has shown that a single EBV strain (Ebnotype) dominates the blood and oropharynx of healthy carriers and that unrelated individuals carry different EBV strains, reflecting the vast polymorphism of Ebnotypes in the general population. Two unexpected observations were made. First, an identical Ebnotype was detected in 4 unrelated individuals, i.e., in the blood of 1 pSS patient and in the saliva of 3 control persons. Second, carriage of 2 to 4 different Ebnotypes by a single individual was observed in 4 cases, i.e., in the blood of 1 pSS patient, and in the blood and saliva of 3 control persons.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial substrate uptake in lambs with and without aortopulmonary shunts during strenuous exercise

Increased myocardial fatty acid uptake during acute exercise could adversely affect myocardial O2 consumption in lambs with left-to-right shunts, which would be unfavorable in view of their decreased coronary blood flow reserve. Therefore, we studied myocardial substrate uptake (glucose, lactate, pyruvate, free fatty acids, triglycerides, beta-hydroxybutyrate, and acetoacetate) in 10 7-wk-old lambs with an aortopulmonary left-to-right shunt [61 +/- 3% (SE) of left ventricular output] and 9 control lambs during strenuous treadmill exercise. The hemodynamic reaction to exercise was similar in shunt and control lambs. The peripheral metabolic response to exercise was also similar in the two groups: glucose free fatty acids, and, most prominently, lactate concentrations increased. Myocardial O2 consumption increased but less in shunt than in control lambs because of a smaller increase in heart rate. In both groups myocardial lactate uptake increased substantially at the cost of other substrates, providing the heart with 40% of its oxidative metabolism. Fatty acid uptake was not different between the two groups. In conclusion, our data reveal no essential differences in myocardial substrate uptake between shunt and control lambs during a substantial circulatory load.

Activation of the immune system of cancer patients by continuous i.v. recombinant IL-2 (rIL-2) therapy is dependent on dose and schedule of rIL-2

The effect of dose and schedule of continuous i.v. rIL-2 infusions on leucocyte subset counts, activation status of CD56+CD3- natural killer (NK) and CD3+ T lymphocytes, and cytolytic activities of peripheral blood mononuclear cells (PBMC) was studied. A single 4-day course of rIL-2 in escalating doses (0.9-11.5 x 10(6) U/m2 per day) was given to 18 patients with various types of metastatic cancer. The serum IL-2 concentration during rIL-2 therapy ranged between 23 and 64 U/ml and was proportional to the administered rIL-2 dose, as was the rebound lymphocytosis following therapy. Before therapy, the CD56+CD3- NK cells expressed low levels of the p75 chain of the IL-2 receptor (IL-2R) and virtually no IL-2R(p55). Most CD3+ T cells were IL-2R(p55-,p75-). Between 2 and 4 days following therapy, i.e. at the time of lymphocytosis, the percentage of CD56+,CD3- NK cells among the lymphocytes had increased proportional to the administered rIL-2 dose. The levels of IL-2R(p75) expression by the CD56+,CD3- NK cells had increased. The percentages of CD3+ T cells expressing IL-2R(p55), HLA-DR and CD45RO had increased proportional to the administered rIL-2 dose. The level of lymphokine- activated killer (LAK) activity against Daudi cells was also positively correlated with rIL-2 dose. Subsequently, seven patients received 4-weekly cycles of rIL-2 (2.9-4.4 x 10(6) U/m2 per day) during 4 consecutive weeks. This schedule led to marked increments in lymphocyte and eosinophil counts, and to increased cytolytic activities compared with pretreatment. We conclude that CD56+,CD3- NK and CD3+ T cells are activated differentially by continuous i.v. rIL-2 proportional to dose and duration of treatment.

Body fluid compartment volumes in chronically hypoxemic lambs

Chronic hypoxemia is associated with a decreased growth rate and a decreased rate of cell division. In lambs with experimental cyanotic heart disease, the gain in body mass was decreased. In this study, we determined to what extent the lower body mass in these lambs was related to alterations in body fluid compartment volumes, specifically whether intracellular volume was decreased. Therefore, fluid compartment volumes were studied in nine lambs, after 3 to 4 wk of experimental cyanotic heart disease, and in 13 control lambs. Hypoxemic lambs had a lower arterial oxygen saturation (65 +/- 11 versus 91 +/- 2%, p < 0.001) and a higher Hb concentration (142 +/- 16 versus 101 +/- 8 g.L-1, p < 0.001). The lower body mass in hypoxemic lambs (10.5 +/- 2.3 versus 13.0 +/- 2.8 kg) could be mainly accounted for by a decrease in intracellular water volume (4.7 +/- 1.3 versus 6.6 +/- 1.5 L, p < 0.01). Total body water (753 +/- 27 versus 780 +/- 40 mL.kg-1) and extracellular water volume (307 +/- 25 versus 277 +/- 15 mL.kg-1) in hypoxemic lambs were not significantly different from those in control lambs, but intracellular water volume was decreased (445 +/- 27 versus 501 +/- 35 mL.kg-1, p < 0.01). The ratio of extracellular to intracellular water volume was higher in hypoxemic lambs (0.69 +/- 0.10 versus 0.55 +/- 0.04, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial blood flow and VO2 in lambs with an aortopulmonary shunt during strenuous exercise

To determine how much myocardial O2 consumption (VO2) would increase during an additional load on the heart in shunt as compared with control lambs, we studied 12 7-wk-old lambs with an aortopulmonary left-to-right shunt (59 +/- 3% of left ventricular output, mean +/- SE) and 11 control lambs during exercise at 80% of their predetermined peak VO2 (VO2peak), at 12 +/- 1 days after surgery. During exercise, systolic aortic pressure increased by 25% in the two groups. Left atrial pressure and left ventricular stroke volume did not change significantly and remained considerably higher in shunt than in control lambs. Heart rate, however, increased less in shunt than in control lambs (163 +/- 8 to 235 +/- 8 vs. 107 +/- 7 to 230 +/- 8 beats/min). The same was true for left ventricular myocardial blood flow (245 +/- 19 to 391 +/- 27 vs. 128 +/- 10 to 320 +/- 45 ml.min-1 x 100 g-1) and myocardial VO2 (847 +/- 101 to 1,692 +/- 136 vs. 528 +/- 58 to 1,579 +/- 178 mumol O2 x min-1 x 100 g-1). We conclude that, despite the volume load, myocardial VO2 of shunt lambs does not increase to a greater extent than in control lambs during a considerable additional load on the heart.

Quantification of fluorescence properties of lymphocytes in peripheral blood mononuclear cell suspensions using a latent class model

Lymphocytes, monocytes, granulocytes, and other blood cells can be distinguished on the basis of their forward (FSC) and sideward (SSC) light scatter properties and their expression of CD45 and CD14. A FSC,SSC gate can be set to include > 95% of the lymphocytes using a "back gating" procedure on the CD45+, CD14- cells. However, nonlymphoid cells such as monocytes have light scattering properties similar to lymphocytes. This problem occurs particularly in patient populations where the light scattering properties of lymphocyte subsets have changed (e.g., due to activation) and are similar to those of the monocytes. Thus, immunophenotyping using antibodies specific for other markers than CD45 and CD14 does not allow a direct assessment of the percentage of all lymphocytes positive for those markers. In order to optimize immunophenotyping we have developed analytic model in which the FSC,SSC dot plot is partitioned into six nonoverlapping light scatter regions. Each light scatter region contains a mixture population of different cell types, i.e., lymphocytes, monocytes, granulocytes, and other cells. The proportions of each cell type are known from the CD45,CD14 expression within each light scatter region. Under the assumption of independence of fluorescence and scatter properties conditional on cell type, the expression of markers other than CD45 or CD14 are derived from the cell type composition and the fluorescence properties on the other markers of each light scatter region. The underlying statistical model is a latent class model, and maximum likelihood estimates are computed using the expectation-maximization (EM) algorithm. The application of the model for immunophenotyping of lymphocytes of healthy individuals and cancer patients receiving immunotherapy is shown.

Three-marker phenotypic analysis of lymphocytes based on two-color immunofluorescence using a multinomial model for flow cytometric counts and maximum likelihood estimation

The simultaneous flow cytometric study of multiple (> or = 3) markers on individual cells is restricted by technical reasons, e.g., the type of flow cytometer, and the availability of (monoclonal) antibodies (mAb) conjugated with the appropriate fluorochromes. However, a n-way classification (n > or = 3) may be derived from multiple 2-way classifications. The 2-way classifications are obtained by the use of only two fluorochromes, but each fluorochrome may be used for the simultaneous labelling of 2 or more mAb. We present a formal statistical model, based on an underlying multinomial distribution for the observed quadrant counts, by which data from such multiple 2-way classifications can be analyzed. The model is restricted to 3-marker phenotypic analyses, but can be extended to n-way classifications (n > 3). Maximum likelihood estimates are obtained by the application of the EM algorithm. The model was tested on 20 samples of peripheral blood mononuclear cells to study the coexpression of CD45RA, CD45RO, and Leu 8 by lymphocyte subsets defined by the CD56 (MHC-unrestricted cytotoxic cells) and CD3 (T cells) markers. Application of the model gave an excellent fit in all but one cases. In addition, the model reduced the effect of inter-assay variation on the estimates and it provided an analysis of consistency over the data, which allows the detection of outliers due to staining errors.

Blood volume and body fluid compartments in lambs with aortopulmonary left-to-right shunts

A left-to-right shunt is accompanied by an increased plasma and blood volume. Since this is likely realized through renin/aldosterone-mediated salt and water retention, other body fluid compartments may be changed too. Therefore, we studied blood volume and body fluid compartments by a single-injection, triple-indicator dilution technique in nine 8-wk-old lambs with an aortopulmonary left-to-right shunt (55 +/- 3% of left ventricular output; mean +/- SEM) and in 11 control lambs, 2.5 wk after surgery. Systemic blood flow was maintained at the same level as in control lambs, but the aortic pressure of the shunt lambs was lower. Blood volume in shunt lambs was larger than in control lambs (110 +/- 6 vs. 84 +/- 7 ml/kg, P < 0.001) through an increase in plasma volume, which correlated significantly with the magnitude of the left-to-right shunt (r = 0.81, P < 0.01). Red blood cell volume was equal to that of control lambs. Evidence was obtained that the increase in plasma volume was induced by a transient increase in renin (8.0 +/- 2.2 vs. 1.6 +/- 0.2 nmol.l-1.h-1; P < 0.02) and aldosterone (0.51 +/- 0.14 vs. 0.24 +/- 0.09 nmol/liter) concentrations. Interstitial water volume, however, was not significantly different from that in control lambs. The amount of intravascular protein was significantly higher than in control lambs (5.0 +/- 0.3 vs. 3.5 +/- 0.2 g/kg body mass, P < 0.001). There were no significant differences in intracellular and total body water volumes between the two groups. We conclude that the increased amount of intravascular protein confines the fluid retained by the kidneys to the vascular compartment.

Distribution of systemic blood flow in lambs with an aortopulmonary shunt during strenuous exercise

We studied regional blood flows with radioactive-labeled microspheres in 12 7-wk-old lambs with an aortopulmonary left-to-right shunt [59 +/- 3% (SE) of left ventricular (LV) output] and in 11 control lambs, at rest and during exercise at 80% of predetermined peak O2 consumption. At rest, systemic blood flow was similar in the two groups. Blood flow to the heart and diaphragm was substantially higher in the shunt than in the control lambs. Blood flow to the other organs was not significantly different between the two groups. During exercise, systemic blood flow increased substantially but less in shunt (81%) than in control lambs (134%). Blood flow to the heart and diaphragm increased, that to the heart still being higher in shunt than in control lambs. Blood flow to the brain did not change, whereas that to the kidneys and splanchnic organs decreased to the same extent (25%) in shunt and control lambs. Intrahepatic and intrarenal blood flow redistribution in the shunt lambs persisted during exercise. In conclusion, myocardial blood flow is not increased at the expense of one particular organ, nor is it associated with an essential change in exercise-induced redistribution in shunt lambs.

Quantitation of polymerase chain reaction products by hybridization-based assays with fluorescent, colorimetric, or chemiluminescent detection

In this report two nonradioactive assays for quantitative analysis of polymerase chain reaction (PCR) products are presented. In the first assay, magnetic beads coated with streptavidin were used to capture biotinylated PCR fragments. After hybridization with a hapten-labeled probe, these beads were analyzed either by flow cytometry (method A) or by immunoenzymatic reactions (method B). Using a dilution series of purified PCR products, we consistently found a lower detection limit of 1.5 fmol for method A than the 0.15-fmol limit for method B. In the second assay we used the peroxidase-based enhanced chemiluminescence system in combination with a cooled charge-coupled device camera to quantify PCR fragments that were spotted on membranes. A linear logarithmic response was observed between the amount of light produced within a certain time interval and the number of DNA molecules. With an exposure time of 5 min, a detection limit of 0.15 fmol was found. Longer exposure times did not result in a higher sensitivity. We conclude that the assays are of sufficient sensitivity for application in quantitative PCR strategies. The nonradioactive technology facilitates implementation of these assays in routine settings.

Optimization of culture conditions for activation and large-scale expansion of human T lymphocytes for bispecific antibody-directed cellular immunotherapy

We investigated the optimal culture conditions (i.e., activation procedure, medium composition and type of culture vessel) for rapid in vitro expansion of large numbers (greater than 5 x 10(9) of blood T lymphocytes. These expanded lymphocytes can be targeted to be cytotoxic to ovarian carcinoma cells with a bispecific monoclonal antibody (BsAb) specific for CD3 and for the ovarian carcinoma-associated antigen MOv18. Both phytohemagglutinin (PHA) and monoclonal antibody (MAb) CD3 induced rapid T-cell proliferation, although the growth kinetics after PHA activation were slightly faster. A 50-fold increase in cell number was obtained after 14 and 16 days for PHA and CD3 MAb, respectively. The induction of BsAb-directed cytolysis was faster after CD3 MAb than after PHA activation of lymphocytes, but became similar around day 20. A mixture of media consisting of 78% RPMI 1640, 20% AIM-V and 2% human plasma (Mix-med) yielded better results than 100% AIM-V medium. Culture of lymphocytes in polyolefin bags, compared with tissue culture flasks, or cryopreservation did not affect lymphocyte yield and function. In most cultures the proportion of CD8+ lymphocytes increased, suggesting a growth advantage of CD8+ over CD4+ lymphocytes in this culture system. A protocol employing PHA activation, Mix-med and polyolefin bags has been used successfully to activate and expand blood lymphocytes for the first 5 patients entered into a phase-I/II clinical trial for the intraperitoneal treatment of ovarian carcinoma using CD3 x anti-MOv18 BsAb-directed T lymphocytes.

Myocardial carbohydrate, ketone, and fatty acid uptake in conscious lambs with aortopulmonary shunts

A left to right shunt increases myocardial work and is often accompanied by increased catecholamine levels. Because both increased myocardial work and increased catecholamine levels may induce increased fatty acid utilization, which could increase resting myocardial oxygen consumption and therefore unfavorably affect coronary reserve, we studied myocardial uptake of glucose, pyruvate, lactate, beta-OH-butyrate, acetoacetate, FFA, and triglycerides in 12 7-wk-old lambs with aortopulmonary left to right shunts (58 +/- 2% of left ventricular output, mean +/- SEM) and in 10 control lambs 2 wk after surgery. Despite the shunt, systemic blood flow in the shunt lambs was maintained at the same level as in the control lambs. This was accomplished by an increased heart rate and stroke volume. Furthermore, the shunt was accompanied by an increased myocardial oxygen consumption in the shunt lambs (834 +/- 70 versus 528 +/- 43 mumol O2.min-1 x 100 g-1; p less than 0.05). There were no significant differences in arterial substrate concentrations between the two groups. The same was true for arteriovenous differences across the myocardium, with the exception of lactate, which was substantially higher in shunt than in control lambs (72 +/- 25 versus 18 +/- 23 mumol/L; p less than 0.05). As a consequence, myocardial lactate uptake in the shunt lambs was increased 15-fold (18 +/- 6 versus 1 +/- 2 mumol.min-1 x 100 g-1; p less than 0.02), whereas uptake of the other substrates merely paralleled the increased myocardial blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Intensification of GVHD prophylaxis interferes with the effects of pretransplant herpes virus serology on the occurrence of grades II-IV acute graft-versus-host disease

The effects of pretransplant herpes virus serology on the occurrence of grades II-IV acute graft-versus-host disease (GVHD) were studied in 262 recipients and their HLA-identical family donors. In 131 recipients on standard GVHD prophylaxis (either methotrexate or cyclosporin A) significant effects were observed for donor HSV serology (seropositivity associated with increased risk for GVHD) and donor EBV serology (seronegativity associated with increased risk). However, these effects were nonsignificant in the other 131 recipients on intensified GVHD prophylaxis (i.e., methotrexate combined with cyclosporin A, in vivo anti-T-cell monoclonal antibodies, or various procedures to reduce the T-cell numbers in the transplants.

Epstein-Barr virus infection in allogeneic marrow grafting: lessons for transplant physicians and virologists

The relationship between Epstein-Barr virus (EBV) and the host is profoundly disturbed by allogeneic bone marrow transplantation (BMT) because EBV resides in the recipient's hematopoietic system, which has to be destroyed in the majority of cases, and in the donor's hematopoietic system, i.e., the marrow graft. We have shown that EBV may be eradicated from some BMT recipients and that the virus may be transferred with the marrow graft. During the immediate post-transplant period oropharyngeal EBV excretion may occur which, by infecting passing B lymphocytes, may act as co-factor for acute graft-versus-host disease and help the virus to survive, despite the temporary depletion of its reservoir. The coexistence of totally different EBV strains in BMT recipients but not in healthy, untransfused controls, suggests that superinfection may by possible in case of immunodeficiency; alternatively, transfer of the virus by the reservoir itself (the B lymphocytes) might be the only effective route for superinfection. The generation of 'variant' strains during viral replication may form the basis of the vast polymorphism between wild-type EBV isolates in the population.

Detection of multiple Epstein-Barr viral strains in allogeneic bone marrow transplant recipients

We have previously shown in 3 allogeneic bone-marrow transplant (BMT) recipients that complete replacement of recipient marrow was associated with the elimination of the pretransplant Epstein-Barr virus (EBV) strain of the recipient. To study the kinetics of EBV elimination and reinfection in more detail, we have performed a longitudinal study of BMT recipients combining serology, virus isolation from mouthwashes and peripheral blood, and EBV strain characterization. Oropharyngeal EBV excretion was found to persist after the cytoreductive therapy prior to BMT, whereas EBV-carrying cells in the blood were detected only after 5 weeks following BMT. During the first month post-BMT, 2 different EBV strains could be isolated from sequential mouth-washes of 3 patients. The initial strains were found to persist up to 7, 21, and 29 days post-BMT, whereas the subsequent strains appeared at 21, 42, and 34 days post-BMT, respectively. Thus, the original EBV strain may persist only for a limited time after BMT, and the oropharyngeal epithelium may be reinfected by a new EBV strain from the blood within 3 weeks. With respect to the coexistence of multiple EBV strains, 2 patterns were evident. From the day 62 mouthwash of 1 patient, 1 Type A and 1 Type B strain were isolated. From the day 180 mouthwash of a second patient, a dominant Type A strain was recovered, together with 6 "variant" strains that differed from each other by only a single EBNA protein (EBNA 1). This pattern may be explained by viral recombinations during replication, which may form the basis for the vast polymorphism of EBV observed in unrelated individuals.

Engineering T lymphocyte antigen specificity

Targeting of immune cells by bispecific antibodies has proven to be a powerful tool for the investigation of cellular cytotoxicity, lymphocyte activation and induction of cytokine production, as well as to represent an innovative form of immunotherapy for the treatment of cancer. The hallmark of this approach is the use of the specificity of monoclonal antibodies to join target and immune cells by virtue of the dual specificity of bispecific antibodies for the two entities. More precisely, the bispecific antibody has two different binding sites, which are capable of recognizing tumor associated antigens on the one hand and lymphocyte activation sites on the other. This process of crosslinking results in the activation of the lymphocyte and triggering of its lytic machinery, as well as lymphokine production. A major advantage of this therapeutic modality is, that use is made of the normal cellular immune defence system and therefore is only associated with minor toxicity. The distinct lymphocyte populations, which can be used for adoptive immunotherapy and the various bispecific antibody preparations, as well as the chimeric immunoglobulin/T cell receptor construction, are the major topics of this review.

Simultaneous flow cytometric detection of antibodies against platelets, granulocytes and lymphocytes

We present a time-saving and objective flow cytometric immunofluorescence assay for the simultaneous detection of antibodies against platelets, granulocytes or lymphocytes using a reconstituted mixture of these cell populations. Platelets, granulocytes and lymphocytes could be distinguished on the basis of their forward (FSC) and sideways (SSC) light scattering properties plotted on scales of 4 log orders. After setting FSC/SSC gates around the platelets, granulocytes and lymphocytes, the reactivity of the sera with the cell populations was determined by histogram analyses of immunofluorescence for each gate. The flow cytometric assay of reconstituted cell mixtures showed a strong, positive correlation with a reference microscopic immunofluorescence assay of separate cell suspensions. The reproducible procedures for the isolation and staining of the cells and the electronic stability of the flow cytometer permitted the use of the same gate and marker settings throughout the experiments. Consequently, the entire analysis of data stored in list mode could be performed using a keystroke, so that time consuming and subjective manual analyses were avoided.

Expression of CD45 isoforms by fresh and activated human gamma delta T lymphocytes and natural killer cells

Naive and primed alpha beta T cells can be distinguished on the basis of their differential expression of CD45RA and CD45RO, respectively. The present study indicates that these CD45-isoforms also identify naive and primed maturational stages of gamma delta T cells and natural killer (NK) cells. In peripheral blood, all V gamma 9-V delta 2 gamma delta T cells reportedly express CD45RO whereas all V delta gamma delta T cells lack CD45RO. Here, we show that these CD45RO- V delta gamma delta T cells all express CD45RA and the CD45RO+ V.9-V delta 2 gamma delta cells lack expression of CD45RA. The V delta T cells acquired CD45RO expression and lost part of their surface CD45RA, following in vitro activation with phytohaemagglutinin or IL-2. Also the CD3-CD16+ NK cells in peripheral blood that are uniformly CD45RA+ CD45RO- completely converted to the CD45RA-CD45RO+ phenotype upon in vitro activation. Moreover, all cloned V.9-V delta 2 and V delta 1 T cells and NK cells express CD45RO and lack expression of CD45RA. Our results strongly suggest that CD45RA and CD45RO are genuine markers for naive and primed lymphocytes that represent distinct differentiation lineages.

Exogenous interleukin 2 recruits in vitro lymphokine-activated killer activity by in vivo activated lymphocytes

Cryopreserved and thawed lymphocytes can be used instead of fresh lymphocytes to avoid test-to-test variability in studies of fluctuations of natural killer (NK) and lymphokine-activated killer (LAK) activities as a function of time. We investigated the effects of 1-h versus 18-h resting of lymphocytes on their lytic activities, because the process of cryopreservation and thawing decreases NK and LAK activities. Lymphocytes from renal cell cancer patients receiving adoptive immunotherapy were studied. An 18-h versus 1-h resting period led to a significant increase in NK activity but had no significant effect on LAK activity. The presence of 1200 IU/ml interleukin 2 (IL-2) in the medium 1 h prior to and during the cytotoxicity (CTX) assay increased in vivo and in vitro IL-2-induced LAK activities. This phenomenon has been interpreted as IL-2 dependency of effector lymphocytes (J.A. Hank, P.C. Kohler, G. Weil-Hillman, N. Rosenthal, K. H. Moore, B. Storer, D. Minkoff, J. Bradshaw, R. Bechhofer, and P. M. Sondel. Cancer Res., 48: 1965-1971, 1988). We performed kinetic studies to assess the role of effector lymphocyte recruitment in these experiments. LAK activity was tested in the presence or absence of IL-2 during preincubations and CTX assays varying between 0 and 120 min. These kinetic studies showed that effector lymphocyte recruitment indeed contributed to the increased level of LAK activity when IL-2 was added to the CTX assay. A minimal incubation period of 30 min was required to detect recruitment of lymphocytes. Effector lymphocytes could be recruited for periods varying between 90 and greater than 240 min, depending on the lymphocyte donor. We conclude that: (a) in vitro, IL-2-mediated recruitment of lymphocytes due to presence of IL-2 in the CTX assay may lead to an overestimate of the actual LAK activity; and (b) in vivo, prolonged IL-2 infusion after the administration of activated lymphocytes seems warranted in order to recruit maximal levels of effector lymphocytes with LAK activity.

Expression of Epstein-Barr virus-encoded growth-transformation-associated proteins in lymphoproliferations of bone-marrow transplant recipients

The expression of Epstein-Barr virus (EBV)-encoded, growth-transformation-associated proteins was studied in lymphoproliferations of 9 allogeneic bone-marrow transplant (BMT) recipients. Immunoblots of cell lysates were probed with polyspecific and monospecific antisera directed against EBNA 1, 2, 3 and 6, and the membrane protein LMP. All tumors expressed EBNA 1 and LMP. EBNA 2 was detected in the tumors of 8 patients, and EBNA 3 and 6 in the tumors of 5 patients. The LMP regulatory sequences, 5' of the LMP gene, were totally unmethylated in all 7 cases, while the coding sequences of LMP and EBNA 2 were more methylated in CpG dinucleotides. EBV-transformed lymphoblastoid cell lines (LCL) express EBNA 1 to 6 and LMP; in contrast, Burkitt lymphomas express only EBNA 1. In vitro experiments have shown that EBNA 2, 3 and LMP can generate targets for cytotoxic T cells (CTL). These combined observations are consistent with the hypothesis that the EBV-associated lymphoproliferative disease of the BMT recipients escapes CTL-mediated rejection due to the failure of host immunosurveillance rather than to the down-regulation of immunogenic EBV-encoded antigens.

EBNA size polymorphism can be used to trace Epstein-Barr virus spread within families

The Epstein-Barr virus (EBV)-determined nuclear antigens EBNA 1, 2, 3, 4, and 6, regularly expressed in EBV-transformed lymphoblastoid cell lines, vary in size among viral strains. We have used this characteristic to trace the spread of the virus within seven families by using an approach called Ebnotyping. Among 33 evaluable individuals, 3 were EBV seronegative, and 17 different EBV strains could be isolated from the peripheral blood or throat washes of the remaining 30. All unrelated persons carried different strains. The EBV strain carried by 19 persons was also found in 1 or more family members. The same viral strain was carried by two members in five families, by three members in the sixth, and by five members in the seventh. The paternal strain was isolated from one child in two families, and the maternal strain was isolated from one or more children in three families. EBV was isolated from both blood and throat wash in six individuals. The Ebnotypes of both derived lymphoblastoid cell lines were identical within each individual. These results indicate that spread within families may be a relatively common route of EBV transmission. The number of horizontal transmission events required to generate diversification of the Ebnotype will require larger epidemiological studies.

Maximal exercise capacity and oxygen consumption of lambs with an aortopulmonary left-to-right shunt

We determined maximal exercise capacity and measured hemodynamics in 10 6-wk-old lambs with an aortopulmonary left-to-right shunt [S, 57 +/- 11%, (SD)] and in 9 control lambs (C) during a graded treadmill test 8 days after surgery. Maximal exercise capacity (3.7 +/- 0.2 km/h and 10 +/- 5% inclination vs. 4.0 +/- 0.9 km/h and 15 +/- 0% inclination, P less than 0.02) and peak oxygen consumption (25 +/- 7 vs. 34 +/- 8 ml O2.min-1.kg-1, P less than 0.02) were both lower in the shunt than in the control lambs. This was due to a lower maximal systemic blood flow in the shunt lambs (271 +/- 38 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.01). Despite their high maximal left ventricular output, which was higher than in the control lambs (448 +/- 87 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.05), the left-to-right shunt could not be compensated for during maximal exercise because of a decreased reserve in heart rate (S: 183 +/- 22 to 277 +/- 38 beats/min; C: 136 +/- 25 to 287 +/- 29 beats/min) and in left ventricular stroke volume (S: 1.8 +/- 0.3 to 1.6 +/- 0.4 ml/kg; C: 1.0 +/- 0.3 to 1.3 +/- 0.2 ml/kg). We conclude that exercise capacity of shunt lambs is lower than that of control lambs, despite a good left ventricular performance, because a part of the reserves for increasing the left ventricular output is already utilized at rest.

A role of herpes virus serology for the development of acute graft-versus-host disease. Leukaemia Working Party of the European Group for Bone Marrow Transplantation

Pretransplant herpes virus serology and acute graft-versus-host disease (GVHD) were studied in 379 leukaemic bone marrow transplant (BMT) recipients and their HLA-identical sibling donors. In logistic multivariate regression analysis pretransplant seropositivity to three or more different herpes viruses among the recipients was the only significant factor associated with grade II-IV acute GVHD (p = 0.03). If this factor was excluded, older donor age (p less than 0.001), absence of T cell depletion (p less than 0.001), pharmacological immunosuppression by monotherapy of methotrexate or cyclosporin versus a combination therapy of both (p = 0.002), and seropositivity to three or more herpes viruses among the donors (p = 0.03) prior to BMT, were also significantly associated with acute GVHD. The data indicate that latent herpes viruses in the host may act as minor histocompatibility antigens or by other means to trigger acute GVHD.

Serological and molecular studies of Epstein-Barr virus infection in allogeneic marrow graft recipients

We have shown in two allogeneic bone marrow transplant recipients that Epstein-Barr virus can be eradicated by the BMT procedure or its complications, and that these patients are susceptible to infection with a new EBV strain. This conclusion was based on a combination of EBV serology and virus strain identification ("Ebnotyping," using the size variations of 5 EBV nuclear antigens). In the present study, we conducted a serological survey of EBV infection in 153 marrow graft recipients and their donors. Ten patients who were positive for IgG antibodies against EBV viral capsid antigens prior to BMT became completely seronegative at a median of 197 days post-BMT (range 106-320 days). Four of these patients, who had received seronegative marrow, remained seronegative during prolonged periods (222 to 2105 days). Six patients had received seropositive marrow. Two of them remained seronegative during their subsequent periods of follow-up (895 and 1437 days). An additional 10 patients showed a 100-fold or greater decrease in VCA IgG antibody titers. Their titers reached a nadir of 10 (the lower limit of positive) at a median of 134 days post BMT (range 83-386 days). The serological patterns of the above 20 patients were particularly frequent among patients with chronic graft-versus-host disease; 12 of 20 patients with decreasing VCA titers (60%) developed chronic GVHD versus only 22 of 73 patients with stable or increasing VCA titers (30%). These results suggest that GVHD may contribute to the elimination of residual EBV-carrying recipient cells. Establishment of EBV-carrying lymphoblastoid cell lines (LCL) was attempted in 60 donor-recipient pairs whose cryopreserved peripheral blood mononuclear cells were available. LCL were established from 18 of 51 EBV-seropositive marrow donors and 10 of 57 seropositive recipients prior to BMT. The same EBV strain was detected in 4 of the 6 cases in which LCL could be established from both the donor and the recipient prior to BMT. The persistence of the original EBV strain was demonstrated in a recipient of a T cell-depleted graft who showed only transient hematological recovery and no GVHD, and was associated with the persistence of B cells of recipient origin.