Adhesion-dependent survival of normal and leukemic human B lymphoblasts on bone marrow stromal cells

We investigated the requirement for intimate contact between bone marrow stroma and B lymphoblasts from normal donors and children with leukemia. By scanning electron microscopy, both normal and leukemic cells seeded onto stroma were surrounded by folds of stromal cells or were linked to the stroma by fine tendrils and uropods. Separation of normal B progenitors from stroma by use of microporous membranes led to significantly lower cell recoveries compared with results when contact was unimpeded. For instance, 22.5% +/- 1.8% (mean +/- SEM) of CD19+, CD34+ cells (most immature subset) were recovered after a 7-day culture directly on stroma, compared with 5.2% +/- 0.7% after growth on membranes (P < .001 by Student's t test). In 6 of 11 cases of B-lineage acute lymphoblastic leukemia, separation of progenitors from stroma resulted in apoptosis and a greater than 60% reduction in cell recovery. In the remaining 5 cases, however, this effect was much less pronounced, with reductions in cell recoveries ranging from 48.5% to less than 1% (median, 39.0%) of control values. Inhibition of very late antigen-4, a surface molecule critical for adhesion of B lymphoblasts to stroma, was associated with a greater loss of normal CD34+ B progenitors compared with that for equivalent leukemic cells. These results establish direct contact with stroma as a survival requirement of normal B lymphoblasts and show marked heterogeneity in stromal dependency among B-lineage leukemic cells.     

Einnahmen aus dem Liquidationsrecht eines Chefarztes für wahlärztliche Leistungen als Arbeitslohn oder als Einnahmen aus selbstständiger Tätigkeit

Abstrakt 1. Wird von den Patienten eines Krankenhauses neben dem Vertrag mit dem Krankenhaus für die Erbringung wahl?rztlicher Leistungen zus?tzlich ein Vertrag mit dem Chefarzt geschlossen, ergibt sich daraus ein unmittelbarer Anspruch des Patienten gegen den Chefarzt auf Erbringung der vereinbarten wahl?rztlichen Leistungen, den der Chefarzt grunds?tzlich „pers?nlich“ zu erfüllen hat, ist das von dem Chefarzt berechnete Honorar an diesen pers?nlich zu zahlen und zieht der Chefarzt oder seine Abrechnungsstelle die Honorare selbst ein, so spricht dies dafür, dass die Einnahmen aus dem Liquidationsrecht für wahl?rztliche Leistungen Einnahmen aus selbstst?ndiger T?tigkeit sind. 2. Auch wenn die wahl?rztlichen Leistungen zu den vertraglich gegenüber dem Krankenhaus geschuldeten Dienstaufgaben geh?ren, ist für die Frage, ob die wahl?rztlichen Leistungen selbstst?ndig oder unselbstst?ndig erbracht werden, eine Abw?gung aller Umst?nde des Einzelfalls vorzunehmen. (Leits?tze des Bearbeiters)     

Acute myeloid leukemia with T-lymphoid features: a distinct biologic and clinical entity

We studied the clinical and biologic features of 10 cases of acute leukemia that met standard French-American-British (FAB) criteria for acute myeloid leukemia (AML) but in which the blast cells also expressed the T-cell-associated CD2 surface antigen. All cases had greater than 3% myeloperoxidase and Sudan black B-positive leukemic blasts, and blasts from seven cases contained Auer rods. Reactivity of the cells with a panel of monoclonal antibodies (MAbs) indicated that leukemic cells in all cases expressed myeloid-associated (CD11b, CD13) surface antigens, further supporting the diagnosis of AML. However, blasts from every patient coexpressed the T-cell-associated surface CD2 and CD7 as well as cytoplasmic CD3 antigens. Blasts from five patients expressed surface CD25, whereas blasts from only one expressed surface CD3. Five patients had rearranged T-cell receptor beta-chain genes, whereas only three had rearranged T-cell receptor gamma-chain genes. This pattern of lineage-related gene expression appears to define a distinct subtype of AML with T-lymphoid features (CD2+ AML) and could reflect either aberrant gene expression in leukemic blasts or transformation of a pluripotent stem cell having a flexible pattern of gene expression. Clinically, these 10 patients presented at an older age with a higher leukocyte count and a higher frequency of lymphadenopathy than did children whose blast cells were characteristic of myeloid leukemia. Patients with CD2+ AML also had poorer responses to remission induction therapy (50% v 80% entered complete remission, P = .05). However, each of the five children who failed induction chemotherapy on AML protocols had a striking response to drug combinations usually reserved for lymphoid leukemia. We conclude that this leukemia with mixed lymphoid and myeloid characteristics is a distinct biologic and clinical entity.     

Rearrangement of the MLL gene confers a poor prognosis in childhood acute lymphoblastic leukemia, regardless of presenting age

MLL gene rearrangements are associated with an extremely poor prognosis in infants with acute lymphoblastic leukemia (ALL), but little is known about their clinical significance in older children. Therefore, we studied 45 cases of childhood ALL with abnormalities of chromosome 11q23 for rearrangement of the MLL gene to determine if this feature confers a uniformly poor prognosis. MLL gene rearrangements were detected in all 18 cases with the common t(4;11), t(9;11) or t(11;19) translocations, whereas only 5 of 12 patients with either unbalanced or uncommon balanced translocations demonstrated a rearrangement. Abnormalities of the MLL gene were not detected in any of the 15 cases with a deletion or inversion of the chromosomes 11q23 region. The presence of an MLL rearrangement was significantly associated with age less than 1 year (P < .001), leukocyte count >50 x 10(9)/L (P = .003), and the absence of leukemic cell CD10 expression (P < .001). In a stratified statistical analysis adjusted for age and treatment protocol, MLL gene rearrangement was correlated with an inferior treatment outcome (P = .028). The 4-year event-free survival estimate (+/- SE) was 10% +/- 6.5% for cases with a rearranged MLL gene and 64% +/- 19.2% for other cases. When infants were excluded from the analysis, MLL rearrangement was still significantly associated with a poor outcome (P = .02), and remained so with the exclusion of t(4;11)- positive cases (P = .05). Thus, regardless of presenting age, MLL gene rearrangement identifies a high-risk subgroup of patients who are not likely to be cured with conventional treatment.     

Thrombocytopenia in dogs induced by granulocyte-macrophage colony- stimulating factor: increased destruction of circulating platelets

Administration of recombinant canine granulocyte-macrophage colony- stimulating factor (rcGM-CSF) to normal dogs in previous studies induced an increase in peripheral blood neutrophils and a dose- dependent decrease in platelet counts. In six dogs that received the highest tested dose of rcGM-CSF (50 micrograms/kg/d) for a minimum of 12 days, the mean nadir of the platelet count was 46,000/microL (range, 4,000 to 91,000/microL) on day 9 +/- 1.1 after starting therapy, compared with a mean baseline platelet count of 398,000/microL (range, 240,000 to 555,000/microL). In three dogs, survival of autologous 111In- labeled platelets was reduced from a mean of 4.9 days to 1.3 days during the administration of rcGM-CSF. Biodistribution studies with gamma camera imaging indicated that there was an increase in mean hepatic uptake during the administration of rcGM-CSF, from 15% to 44% of the total injected 111In-labeled platelets at 2 hours, whereas splenic uptake was not significantly changed. In contrast, in two evaluable dogs who were recipients of 111In-labeled platelets from matched allogeneic donors receiving rcGM-CSF, platelet survival was not reduced and no increased hepatic uptake was noted. A third dog became alloimmunized to the matched donor platelets and was not evaluable. Immunohistologic studies of liver and spleen were performed with monoclonal antibodies specific for canine gpIIb/IIIa and P-selectin in dogs treated with rcGM-CSF and compared with untreated controls. On treatment, a marked reduction of platelets in the red pulp of the spleen was evident, and in general, the presence of platelet antigen in the liver was unchanged. Therefore, platelets were not being sequestered, but destroyed in the liver and spleen. The platelet antigens, P-selectin and gpIIb/IIIa, were identified in association with Kupffer cells in the liver, but no difference in the number of distribution of these Kupffer cells was found between controls and rcGM- CSF-treated dogs. In the spleen during rcGM-CSF treatment, most platelet antigens were associated with large mononuclear cells in the marginal zone. During administration of rcGM-CSF, CD1c and CD11c expression was increased on Kupffer cells. Platelet P-selectin expression and binding of leukocytes to circulating platelets were unchanged from baseline studies with rcGM-CSF treatment. In conclusion, during the administration of rcGM-CSF to dogs, a local process in the liver and spleen is induced resulting in thrombocytopenia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparison of fractionated to single-dose total body irradiation in conditioning canine littermates for DLA-identical marrow grafts

We explored the ability of fractionated total body irradiation (TBI) given at a rate of 7 cGy/min from opposing dual 60Co sources at otherwise lethal doses of 450, 600, 700, 800, and 920 cGy to condition dogs for marrow grafts from DLA-identical littermates. Results were compared with those of a previously reported study using single-dose TBI administered under otherwise identical conditions. Fractionated TBI was less immunosuppressive than single-dose TBI, as evidenced by a significantly higher rate of graft rejection (P = .001). Specifically, sustained allogeneic engraftment was observed in only two of 18 (11%) dogs that received 600 to 800 cGy fractionated TBI as compared with 11 of 17 (65%) dogs that received comparable doses of single-dose TBI. Only at 450 cGy (none of the ten dogs studied had sustained engraftment) and at 920 cGy (four of five dogs that received fractionated and 20 of 21 dogs that received single-dose TBI engrafted) were we unable to find differences between the two modes of radiation. Most dogs that rejected their graft survived with autologous recovery (13 of 22 that received fractionated and eight of 12 that received single-dose TBI; P = .49), presumably the result of extended support provided by the transient allogeneic grafts. We conclude that at equivalent doses fractionated TBI is significantly less effective than single-dose TBI to condition DLA-identical littermate dogs for marrow transplantation. These findings have implications for the design of conditioning programs in clinical transplantation, especially when T- cell-depleted marrow grafts are used.     

Prolonged survival of B-lineage acute lymphoblastic leukemia cells is accompanied by overexpression of bcl-2 protein

Overexpression of bcl-2 delays the onset of apoptosis in lymphohematopoietic cells. We measured levels of bcl-2 protein in normal and leukemic human B-cell progenitors with a specific monoclonal antibody and flow cytometry. Normal immature B cells had low levels of bcl-2 protein; the intensity of fluorescence, expressed as molecules of soluble fluorochrome per cell, within CD10+ cells was 3,460 +/- 1,050 (mean +/- SD; 5 samples). In 16 cases of B-lineage acute lymphoblastic leukemia (ALL), cells had levels of bcl-2 that were strikingly higher than those of their normal counterparts (33,560 +/- 14,570; P < .001 by t-test analysis). We next investigated whether the intensity of bcl-2 expression correlated with the resistance of immature B cells to in vitro culture. In 12 cases of B-lineage ALL, the cells recovered after 7 days of culture on allogeneic bone marrow stromal layers were 69% to 178% (median, 95.5%) of those originally seeded. Prolonged survival of leukemic cells in vitro was observed even in the absence of stromal layers in 6 of these 12 cases; the intensity of bcl-2 protein expression in these cases was 45,000 +/- 13,270, compared with 21,500 +/- 7,260 in the 6 cases in which greater than 99.5% of cells rapidly died by apoptosis under the same culture conditions (P = .003). Five immature B-cell lines, continuously growing in the absence of stroma, had the highest bcl-2 expression (79,400 +/- 20,330). By contrast, most normal CD19+, sIg-immature B cells died despite the presence of bone marrow stromal layers; 9.7% to 28.2% were recovered after 7 days of culture in three experiments. We conclude that abnormal bcl-2 gene expression influences the survival ability of B-cell progenitors. This may contribute to leukemogenesis and explain the aptitude of leukemic lymphoblasts to expand outside the bone marrow microenvironment.     

Clinical significance of CD34 expression in childhood acute lymphoblastic leukemia

The CD34 antigen was detected on > or = 10% of the blast cells in 235 (70%) of 335 cases of newly diagnosed childhood acute lymphoblastic leukemia (ALL) treated in two consecutive chemotherapy trials. By immunophenotype, the distribution of positive cases favored early pre-B ALL (83%; n = 180) followed by pre-B ALL (61%; n = 89) and then T-cell ALL (46%; n = 61) (P < .001). Among the B-lineage cases, CD34 expression was significantly associated with favorable presenting features: age 1 to 10 years, white race, absence of central nervous system (CNS) leukemia, low serum lactate dehydrogenase level, CD10 expression, and leukemic cell hyperdiploidy (> 50 chromosomes or DNA index > or = 1.16). Event-free survival was clearly superior for patients with CD34+ leukemia (P = .01), with an estimated 83% +/- 6% (SE) of the cohort remaining free of adverse events at 5 years post diagnosis, as compared to 63% +/- 10% of the group without this feature. Multivariate analysis showed that the prognostic influence of the antigen was independent of age, leukocyte count, and other well- recognized factors, suggesting that it would add discriminatory power to current systems of risk assignment. Findings in T-cell ALL were the reverse: CD34 expression showed positive correlations with initial CNS leukemia and CD10 negativity but not with any good-risk presenting characteristics. Log-rank analysis indicated no adverse effect on treatment outcome by CD34 antigen expression, although additional patients with need to be studied to obtain a definitive answer. The opposed clinical associations of CD34 expression in B- and T-lineage ALL may reflect fundamental biologic differences between these leukemia species.     

Hypodiploidy is associated with a poor prognosis in childhood acute lymphoblastic leukemia

Leukemic cells from 31 (7.6%) of 409 children with newly diagnosed acute lymphoblastic leukemia (ALL) had a hypodiploid karyotype. The patients' ages ranged from 0.8 to 17 years (median, 5 years) and their initial leukocyte counts from 1.0 to 132 X 10(9)/L (median, 12.7 X 10(9)/L). Modal chromosome numbers for the leukemic stem lines were 45 in 26 cases, 28 in two cases, and 26, 36 and 43 in one case each. Seven cases had one to three additional abnormal lines due to clonal evolution. Chromosome 20 was lost most frequently (nine cases). Structural abnormalities--including chromosomal translocations (21 cases), deletions (ten cases), duplications (two cases), or inversions (one case)--were common findings; the nonrandom translocations consisted of the t(1;19)(q23;p13.3) in two pre-B cases and tdic(9;12)(p1?1;p1?2) in three cases of common ALL. When compared with hyperdiploid cases (greater than 50 chromosomes), ALL with hypodiploidy was found to have a poorer outcome and was more likely to be associated with chromosomal translocations, higher serum lactic dehydrogenase levels, and age less than 2 or greater than or equal to 10 years. Moreover, patients with hypodiploid ALL fared as poorly as those with pseudodiploid karyotypes, even though their leukocyte counts and serum lactic dehydrogenase levels were lower and they had a comparable frequency of leukemic cell translocations. Hypodiploidy is therefore an unfavorable karyotypic feature in childhood ALL.