Phenotypic, genotypic, cytochemical, and ultrastructural characterization of acute undifferentiated leukemia

During the diagnostic investigation of 750 acute leukemias, nine cases were morphologically, cytochemically, and phenotypically undifferentiated. In seven of these cases the blasts were class II+, CD34+ and TdT+, in one were class II+, TdT+, CD7+ while in the remaining leukemia blasts expressed class II only. Cytoplasmic and membrane CD22, CD3, CD13, and Ig as well as membrane CD19, CD10, CD37, CD2, CD33, CD14, glycophorin C, and CD61 were absent. The further characterization of these rare leukemias yielded the following results. The TCR-beta, -gamma and -delta genes were in germline configuration in seven cases studied while IgH genes were rearranged on both alleles in two cases and germline in the other five. By ultrastructural analysis peroxidase activity was detected on unfixed cells in a minority of blasts from four of seven cases. In two of the peroxidase-positive cases a small proportion of blasts also reacted with an anti-myeloperoxidase monoclonal antibody. In one of the peroxidase-negative cases, 7% of blasts were labeled by the antibody, suggesting the presence of peroxidase in its proenzyme form. Importantly, the two cases with Ig gene rearrangements did not have cytochemically or immunologically detectable peroxidase. Three of the nine patients were treated as ALL while six received AML chemotherapy. In five patients complete remission was achieved while the other four died from infections during remission induction. Four patients are still in remission 7, 12, 24, and 30 months after diagnosis while one patient relapsed after 12 months. In conclusion, we have characterized the genotypic and ultrastructural features of subtype of acute leukemia in which blasts expressed immaturity markers and lacked lineage associated antigens. In contrast to previously reported "unclassifiable" cases, the leukemias were phenotypically homogeneous and showed a good response to chemotherapy.

The immunologic detection of minimal residual disease in acute leukemia

Certain combinations of differentiation antigens are expressed on leukemia blasts and are absent or extremely rare among normal progenitors in the fetal liver and fetal and regenerating bone marrow. These combinations include cCD3/TdT, a thymic feature retained on thymic-acute lymphoblastic leukemia (T-ALL) blasts outside the thymus, and the coexpression of TdT and myeloid markers (CD13, CD33) on a proportion of ALL and acute myeloid leukemia (AML). Thus, double marker immunofluorescence assays are operationally leukemia-specific and can be applied in 35% of acute leukemias for detecting minimal disease at a less than 10(-4) level; only rare cases, 2 of 35 in our study, switch these relevant features during relapse. The sensitivity and specificity of these assays was tested as follows. First, bone marrow samples taken from patients who had originally presented with blasts expressing the leukemia-associated combinations but were in full morphologic remission were studied, and varying numbers (less than 0.01% to 10% of the mononuclear fraction) of cells with aberrant features were identified in 11.6% of the cases. Second, the outcome of 19 patients with minimal disease identified immunologically while in complete morphologic remission was investigated: all 19 patients have developed systemic relapse within 4 to 25 (median 14.5) weeks. In contrast, 17 of 25 patients also morphologically in complete remission and without residual disease identifiable immunologically after repeated testing are still in morphologic and immunologic remission (follow-up 17 to 114 weeks, median 28 weeks). Only eight patients in this group have relapsed so far: in two patients the relapse was localized in the cerebrospinal fluid, while in six patients a systemic relapse was observed 6 to 51 (median 21.5) weeks after the last negative immunologic bone marrow examination. In conclusion, no false-positive results were detected with these sensitive assays, and the introduction of appropriately planned prospective studies, including the immunologic detection of residual leukemia, is justified on the basis of these observations.

Variable corticosteroid sensitivity of thymic cortex and medullary peripheral-type lymphoid tissue in myasthenia gravis patients: structural and functional effects

The thymus has been studied in myasthenia gravis patients to assess the effects of previous immunosuppression on total yields of cell suspension, immunohistology and culture responses. The reduction in cell yields by pretreatment with corticosteroid was very variable. In 16 of 32 cases, cortical, medullary and total cell numbers were all greatly reduced ('depleted cases'), whereas in the others, they were within or near the typical range for untreated myasthenics. Cortical thymocytes were even more depleted than precursor thymic blasts. Thus the interpatient differences in sensitivity to corticosteroid recently described for mature T cells also affected immature cortical thymocytes and their differentiating medullary progeny. In the medulla, mature (CD3+) T lymphocytes and germinal centres were enriched by the loss of cortex and appeared relatively healthy, but somewhat depopulated. Concomitantly, in-vitro T-cell responses to acetylcholine receptor (AChR) and production of anti-AChR antibody and total IgG by thymic cells were usually well within the typical range (assessed per 10(6) cells). Moreover, the total productivity of the entire thymus was reduced almost entirely by the cellular depopulation rather than by decreased function per surviving cell. Thus the main actions of this alternate day therapy with corticosteroids were apparently on total peripheral cell numbers, and perhaps on activated cells and effector mechanisms too, and its thymic effects were inessential.

Expression of T-cell receptors TcR1 (gamma/delta) and TcR2 (alpha/beta) in the human intestinal mucosa

Cryostat sections of normal human adult gastrointestinal mucosae were studied by double-label immunofluorescence with antibodies to CD3, CD4, CD8, CD5 and CD6, in parallel with antibodies beta F1 and TCR delta 1 against beta-chains and delta-chains of the T-cell receptor (TcR) types TcR2 (alpha/beta) and TcR1 (gamma/delta), respectively. Virtually no TcR1+ were found within the lamina propria. In the epithelial compartment, TcR1+ cells were infrequent: in the small bowel, congruent to 2% of T cells were TcR1+. In the colonic epithelium, the percentage of T cells expressing gamma/delta-chains was higher, with a mean value approximating 15-20%, although this apparently large percentage increase compared with small bowel reflects in part a much lower density of colonic IEL, as absolute numbers of TCR delta 1+ cells were comparable. Of the TcR1+ population, about half were CD4- CD8-, 'double negatives' and the remainder were CD8+. TcR1+ cells were also CD5- CD6-, irrespective of expression of CD8. No CD4+ cells expressing TcR1 were observed: essentially all CD4+ cells were beta F1+, with some variability of labelling intensity. Approximately 30-50% of the CD8+ subset expressed the beta F1 antigen strongly. However, in the remaining TcR1- CD8+ cells, which were all of the CD5- CD6- phenotype, expression of the beta F1 antigen was only detectable when streptavidin and biotin conjugates were used for amplification of labelling. Thus, the CD8+ CD5- subset, a prominent population of the epithelial compartment of the small bowel, was either TcR2dull in the majority or TcR1+ in a minority. Our data imply that gamma/delta TcR1 cells may be actively excluded from intestinal lamina propria, and that any preferential localization that does occur is limited and is rather a feature of the colonic mucosa, rather than the small bowel.

The reliability of cytoplasmic CD3 and CD22 antigen expression in the immunodiagnosis of acute leukemia: a study of 500 cases

Current views about the origin of acute lymphoid leukemia (ALL) emphasize the importance of maturation arrest at a precursor cell level. Recently, the CD22 antigen has been identified in the cytoplasm of normal bone marrow-borne immature B lineage cells, while the CD3 antigen (epsilon chain) has been detected within normal immature thymic blasts. In the first part our study performed on 100 cases of known acute leukemias, the expression of such cytoplasmic molecules, referred to as cCD22 and cCD3, was analyzed together with their appearance in the leukemic cells' membrane (mCD22 and mCD3). The presence of cCD22 in B-lineage ALL and that of cCD3 in T-ALL has indeed fully confirmed the diagnosis reached by other markers, and mCD22 and mCD3 were expressed on only a few cases of B- and T-lineage ALL, also revealing a degree of developmental asynchrony within leukemic blasts. In the subsequent analysis both cCD22 and cCD3 have been included in a standard panel of diagnostic reagents applied on 500 consecutive cases of acute leukemia. Here the aim was to analyze both the diagnostic precision of individual markers and the heterogeneity of various leukemic types in terms of the expression of membrane and intracellular antigens and their cytochemical features (Sudan Black B and esterases). It has been found that cCD22 and cCD3 are exquisitely specific for B-precursor ALL (TdT+, CD19+) and T-ALL (TdT+, CD7+), respectively, while both markers are absent in acute myeloblastic leukemia (AML) and acute myelomonocytic and monocytic leukemia (AMML/AMoL). These observations contrast the findings which demonstrate that 31% of cases among nonlymphoid acute leukemia (including AML and AMML) express CD7 and/or TdT. The study of myeloid antigens detected by CD13, CD33, and CD14 is also informative and complementary, both in diagnosing and subdividing the AML and AMML/AMoL groups. The peculiar main observation of this study is that only with the combined use of these markers in a microplate assay for membrane antigens, followed by double staining for intracellular antigens such as terminal deoxynucleotidyl transferase, cCD3, cCD22, c mu heavy chain, and T cell receptor beta, it is possible to safely establish the lineage affiliation and subgrouping of virtually all acute leukemias. Among these cases are those with aberrant combinations of markers, including 14% of B-lineage ALL (cCD22+,CD19+,TdT+) and a single case T-ALL (cCD3+,CD7+,TdT+), which exhibit CD13 and/or CD33 antigens, cases with mixtures of ALL and AML blasts, and 1.2% of acute leukemias which lack lineage affiliation and can be regarded as acute undifferentiated leukemia.

The expression of T cell receptor-associated proteins during T cell ontogeny in man

The expression of TCR-associated molecules was examined in human fetal and postnatal tissues. From gestational wk 7 onward in the fetal liver, putative prothymocytes have been identified with cytoplasmic CD3 positivity (cCD3+). These immature cells are TdT- and do not express membrane CD3 (mCD3-) or TCR beta identified by beta F1, but show CD7 and CD45 positivity without CD1, CD2, CD5, CD4, CD8, CD10, and class II Ag. Their high proliferative activity is indicated by greater than 85% Ki67 positivity. After the 10th wk, beta F1+, mCD3+ cells also appear in the liver and these are mostly Ki67- but no TCR gamma delta-bearing cells can be identified at such an early stage of extrathymic development. In the mCD3- TdT-fetal thymus (10 1/2 to 18th wk) cCD3+, mCD3- CD1-blasts proliferate (Ki67+) and lack TCR-beta or TCR-gamma delta. The TdT-, CD1+ cortical thymocytes develop into TCR-beta + and WT31-positive (TCR-alpha beta +) cells. Subsequently TdT-positive thymocytes become detectable around 19 to 20 wk, and in such glands the peak of proliferative activity is seen among TdT+, cCD3+ cells which appear to acquire, in a regular sequence, cytoplasmic beta F1 (TCR-beta), mCD3, and TCR-alpha beta (WT31 positivity) together with the loss of TdT and Ki67 positivity. A newly described transitional population of cells is TdT-, beta F1+ but exhibits no detectable WT31 positivity. These cells correspond to the CD1+, mCD3+ thymocytes and are probably the targets of thymic selection. The cells of the TCR-gamma delta lineage, detected by mAb TCR-delta-1 and delta TCS1, are rare (0.02 to 0.5%) among thymocytes from gestational wk 10 1/2 onward through the whole span of thymic development, but these cells include a proportion (18 to 59%) of cells expressing CD1 Ag, suggesting that these TCR-gamma delta cells differentiate in the thymus. Among the CD1+, TCR-gamma delta + thymocytes, no TdT positivity can be detected.

The expression of T cell receptor-associated proteins during T cell ontogeny in man

The expression of TCR-associated molecules was examined in human fetal and postnatal tissues. From gestational wk 7 onward in the fetal liver, putative prothymocytes have been identified with cytoplasmic CD3 positivity (cCD3+). These immature cells are TdT- and do not express membrane CD3 (mCD3-) or TCR beta identified by beta F1, but show CD7 and CD45 positivity without CD1, CD2, CD5, CD4, CD8, CD10, and class II Ag. Their high proliferative activity is indicated by greater than 85% Ki67 positivity. After the 10th wk, beta F1+, mCD3+ cells also appear in the liver and these are mostly Ki67- but no TCR gamma delta-bearing cells can be identified at such an early stage of extrathymic development. In the mCD3- TdT-fetal thymus (10 1/2 to 18th wk) cCD3+, mCD3- CD1-blasts proliferate (Ki67+) and lack TCR-beta or TCR-gamma delta. The TdT-, CD1+ cortical thymocytes develop into TCR-beta + and WT31-positive (TCR-alpha beta +) cells. Subsequently TdT-positive thymocytes become detectable around 19 to 20 wk, and in such glands the peak of proliferative activity is seen among TdT+, cCD3+ cells which appear to acquire, in a regular sequence, cytoplasmic beta F1 (TCR-beta), mCD3, and TCR-alpha beta (WT31 positivity) together with the loss of TdT and Ki67 positivity. A newly described transitional population of cells is TdT-, beta F1+ but exhibits no detectable WT31 positivity. These cells correspond to the CD1+, mCD3+ thymocytes and are probably the targets of thymic selection. The cells of the TCR-gamma delta lineage, detected by mAb TCR-delta-1 and delta TCS1, are rare (0.02 to 0.5%) among thymocytes from gestational wk 10 1/2 onward through the whole span of thymic development, but these cells include a proportion (18 to 59%) of cells expressing CD1 Ag, suggesting that these TCR-gamma delta cells differentiate in the thymus. Among the CD1+, TCR-gamma delta + thymocytes, no TdT positivity can be detected.

Autologous bone marrow transplantation in acute lymphoblastic leukemia--preclinical immunologic studies

Immunologic aspects of autologous bone marrow transplantation (ABMT), immunodiagnosis, patient monitoring, and the purging of bone marrow have been studied in individual patients. It was demonstrated that the most sensitive method for detecting lymphoid cells which show the phenotypes of ALLs of B or T lineage was double immunofluorescence staining for nuclear terminal transferase (TdT) and B or T lineage antigens. With the help of these sensitive tests in the presence of rabbit complement (C'), MAbs CD10 (RFAL3 of IgM class), CD19 (SB4 of IgM class), and their cocktail were capable of eliminating greater than 3 log blast cells of B lineage ALL in 84%, 75.5%, and 90% of cases, respectively. The same reagents lysed 26.8%, 0%, and 45% of blasts in the presence of human C'. CD7 (RFT2, IgG2) eliminated greater than 3 log T-ALL blast cells in 73% of cases. The proliferative fractions of leukemic blasts were also TdT+ and sensitive to lysis with MAb and C'. On the basis of these observations MABs were selected for purging in 36 patients undergoing ABMT in first remission (10 patients considered to be at a high risk of relapse), second and third remissions (23 and 2 patients), and without entering into remission (1 patient). The efficacy of eliminating the MAb-reactive cells from the bone marrow inoculum was also documented in five patients. By the use of sensitive immunologic assay (TdT/cytoplasmic CD3 double staining) in patients with T-ALL, no residual leukemia (less than 10(-4] could be detected at the time of transplantation. Following an observation period of 5-34 months, 24 of the 36 patients are alive and well with no procedure-related mortality.

Proliferation of normal and malignant human immature lymphoid cells

In this study, the proliferative activity of human B and T cell precursors in central lymphoid organs, acute lymphoblastic leukemia (ALL) cells, and permanent cell lines was investigated with double- and triple-color-labeling methods for the analysis of cell cycle-associated features such as 5-bromo-2'-deoxyuridine (BrdU) incorporation and the expression of a nuclear proliferation-associated antigen, Ki67, together with the phenotypic profile of the cells. In infant and regenerating bone marrow (BM), 41.5% +/- 4.0% of terminal deoxynucleotidyl transferase (TdT+) cells were Ki67+, and 30.0% +/- 4.0% incorporated BrdU. A similar proportion of TdT+ dividing cells was observed in adult BM. The proliferative activity of the B cell progenitors reached the peak at the pre-B stage: 80.8% +/- 7.6% and 35.3% +/- 6.1% of c mu +, RFB7- cells were Ki67+ and BrdU+, respectively. In contrast, greater than 95% of surface immunoglobulin-positive BM lymphocytes were resting cells. In infant thymus the highest dividing capacity (95% Ki67+, 60% to 90% BrdU+) was observed in large cortical thymocytes (TdT+, CD1-, cCD3+), and TdT+, CD1+ cortical thymocytes also showed a high proliferative activity (74.3% +/- 2.3% Ki67+, 22.0% +/- 1.0% BrdU+), but TdT-, mCD3+ thymic lymphocytes were mainly resting cells (less than 5% Ki67+, less than 1% BrdU+). The proliferative activity of null and common ALL blasts was significantly lower than that of normal BM TdT+ cells (15.5% +/- 4.2% Ki67+, 6.2% +/- 2.1% BrdU+; P less than .001). Dividing ALL blasts were TdT+ and expressed surface antigens detected by CD10 and/or CD19 antibodies. In T cell-ALL, the percentages of Ki67+ and BrdU+ blasts were also lower than those found in the corresponding normal immature thymocytes (13.0% +/- 3.1% and 2.4% +/- 1.3%, respectively; P less than .001). Thus, ALLs derive from actively proliferating lymphoid precursors but have a lower dividing capacity than the corresponding normal cell types. In ALL cases with heterogeneous expression of markers such as cmu and CD1, dividing blasts were distributed among both negative and positive populations, thus indicating that blasts with signs of differentiation also remain within the dividing pool.

Double and triple staining methods for studying the proliferative activity of human B and T lymphoid cells

New methods for double and triple colour labelling using monoclonal antibodies to the proliferation-associated markers 5-bromo-2'-deoxyuridine (BrdU) and Ki67 are described. In order to make incorporated BrdU accessible to most anti-BrdU antibodies, mild denaturation of the DNA is needed, and this is usually obtained by exposing the cells to acid or base. This procedure destroys most cellular antigens, including nuclear TdT and Ki67. In this study we show that fixation in cold methanol, instead of 70% ethanol, for 30 min followed by immersion in 7 X 10(-3) N NaOH for 10-15 s allows BrdU staining with the simultaneous detection of nuclear, cytoplasmic and membrane antigens as well as preservation of morphological detail. This method is optimal for detection of nuclear Ki67 and TdT. These reagents together with antibodies to membrane antigens can be included in triple colour labelling using second layers conjugated to FITC, TRITC and colloidal gold. With these methods it is now possible to characterize the phenotype of dividing cell populations such as precursors in central lymphoid tissues and germinal centre blasts in peripheral lymphoid organs.

Recombinant interleukin 2 and anti-Tac influence the growth of enriched multipotent hemopoietic progenitors: proposed hypotheses for different responses in early and late progenitors

Experiments were designed to evaluate the effect of recombinant IL-2 on growth of hemopoietic precursors from different sources (normal cord blood and bone marrow, and PB from CGL patients). For this purpose, combined cell sorting techniques and multipotent colony forming cell assays were used. A monoclonal antibody BI-3C5, which recognizes an antigen present on early lympho-myeloid cells as well as on all colony forming cells (CFU-GEMM assay), was used to enrich the studied populations. Double colour immunofluorescence techniques were performed to analyse the expression of Tac antigen on early progenitors. The results showed that rIL-2 had a stimulatory effect on growth of enriched progenitors from the three sources and surprisingly that addition of anti-Tac did not abolish this effect. On the contrary, anti-Tac enhanced even more growth of these sorted BI-3C5 precursors, suggesting a ligand action of the antibody. More interestingly, a low percentage of cord cells (1 in 1000) expressed both BI-3C5 and Tac antigens. The vast majority of cells did not concomitantly express both markers. The double labelled cells had a lymphoid-like morphology, high nucleus/cytoplasmic ratio and 2-3 nucleoli. The results will be discussed focusing on early and late "stem" cell growth.

Correlation of immunophenotype with rearrangement of T cell antigen receptor beta and gamma genes in acute lymphoblastic leukemia of adults

The structure of immunoglobulin heavy chain (IgH) and T cell antigen receptor (TCR) beta and gamma chain genes was studied in 38 cases of adult and two cases of childhood acute lymphoblastic leukemia (ALL). Seven cases of T-ALL all showed clonally rearranged TCR beta and gamma genes; only one of these also contained rearranged IgH genes. All precursor B cell ALLs and one case of unusual B cell ALL/lymphoma had clonally rearranged IgH genes, but a high proportion (22 of 32, 69%) of precursor B cell ALLs also had rearrangement of TCR beta and/or gamma genes. TCR beta gene rearrangement was less common in more mature precursor B cell ALL, expressing cytoplasmic IgM (pre-B-ALL) (0 of 5) than in other precursor B cell ALL cases (15 of 27). In the precursor B cell ALLs overall, 10 (32%) had rearrangement of both beta and gamma genes, while 7 (22%) had rearrangement of TCR gamma genes only. A further 5 (16%), all expressing one or more unusual immunophenotype markers, had TCR beta gene rearrangement without detectable gamma gene rearrangement. These observations, together with certain characteristics of constant-joining region usage of both TCR genes (a preference for rearrangement into the C beta 2 and C gamma 1 genes), distinguishes these "inappropriate" rearrangements from those found in T-ALL and suggests that they have arisen through a differentiation arrest which is not part of a normal T cell developmental program.

Rearrangement of immunoglobulin and T cell antigen receptor genes in acute myeloid leukemia with lymphoid-associated markers

Ten cases of adult acute myeloid leukemia (AML) displaying lymphoid-associated markers CD7 and/or terminal deoxynucleotidyl transferase (TdT) have been investigated for rearrangement of immunoglobulin and T cell antigen receptor beta and gamma genes. Two of six TdT+ cases had clonally rearranged Ig genes, whereas six of eight CD7+ AMLs, including three that were TdT+, had a germ line configuration of both immunoglobulin and T cell receptor beta and gamma genes. A single case of CD7+ TdT- AML had clonal rearrangement of all three genes. These results indicate that expression of TdT and/or CD7 is not accompanied by gene rearrangement in most cases of adult AML. A minority of cases, displaying lymphoid-associated phenotypic markers and accompanying gene rearrangement, may represent a distinct subgroup of AML that arises from a rare, primitive stem cell, possessing extensive multilineage potential.

The cytoplasmic expression of CD3 antigens in normal and malignant cells of the T lymphoid lineage

Anti-CD3 (T3) Ab reacting with different proportions of thymocytes (anti-CD3a: UCHT1, anti-CD3b: T10B9, and anti-CD3c: OKT3) were tested for cytoplasmic (cCD3) and membrane (mCD3) expression in the bone marrow, thymus, and blood in man and selected primates. The expression of cCD3a and cCD3c in the perinuclear and Golgi area of large, BrdU-incorporating, strongly TdT+ thymic blasts probably represents one of the earliest signs of T cell commitment, because these blast cells are CD1-, CD4-, CD8-, and mCD3-. The cCD3+, TdT+ cells are normally restricted to the thymus and are absent among the TdT+ cells of bone marrow. The anti-CD3b Ab used, T10B9, co-caps and co-modulates with the other anti-CD3 Ab and is a T cell-specific reagent at a membrane level but does not bind to perinuclear cCD3. Instead, this reagent cross-reacts with a filamentous cytoplasmic network in non-T cells in man and in primates S. oedipus and M. rhesus despite their T cell negativity for mCD3. The characteristics of all T-ALL cases studied: cCD3+, CD7+ along with nuclear TdT+ suggest lineage fidelity to early thymic blasts. As a marked contrast, cCD3 is absent in common ALL and in AML, including cases that concomitantly express CD7 and myeloid antigens. Thus, the cCD3, TdT combination provides a very sensitive assay for residual T-ALL blasts outside the normal thymus.

The cytoplasmic expression of CD3 antigens in normal and malignant cells of the T lymphoid lineage

Anti-CD3 (T3) Ab reacting with different proportions of thymocytes (anti-CD3a: UCHT1, anti-CD3b: T10B9, and anti-CD3c: OKT3) were tested for cytoplasmic (cCD3) and membrane (mCD3) expression in the bone marrow, thymus, and blood in man and selected primates. The expression of cCD3a and cCD3c in the perinuclear and Golgi area of large, BrdU-incorporating, strongly TdT+ thymic blasts probably represents one of the earliest signs of T cell commitment, because these blast cells are CD1-, CD4-, CD8-, and mCD3-. The cCD3+, TdT+ cells are normally restricted to the thymus and are absent among the TdT+ cells of bone marrow. The anti-CD3b Ab used, T10B9, co-caps and co-modulates with the other anti-CD3 Ab and is a T cell-specific reagent at a membrane level but does not bind to perinuclear cCD3. Instead, this reagent cross-reacts with a filamentous cytoplasmic network in non-T cells in man and in primates S. oedipus and M. rhesus despite their T cell negativity for mCD3. The characteristics of all T-ALL cases studied: cCD3+, CD7+ along with nuclear TdT+ suggest lineage fidelity to early thymic blasts. As a marked contrast, cCD3 is absent in common ALL and in AML, including cases that concomitantly express CD7 and myeloid antigens. Thus, the cCD3, TdT combination provides a very sensitive assay for residual T-ALL blasts outside the normal thymus.

Multiple chromosome abnormalities in a drug resistant TdT positive B-cell leukemia

A 17-year old caucasian male presented with B-cell acute leukemia which proved aggressive and refractory to treatment. Cytogenic investigation showed a single clone with a complex karyotype 49,XY,del(2)(p13),+4,del(4)(p11),-6,+i(6)(p),+7,+8, t(8;14), (q24;q32),del(17)(p11). This includes the Burkitt's translocation and a deletion at the site of the immunoglobulin kappa light chain gene. Clonal evolution included tetraploidy, duplication of the derived chromosomes and, terminally, trisomy 1q. Immunological investigation revealed a monoclonal population of B-cell blasts, expressing the kappa light chain, and with an extremely rare combination of SIg and TdT positivity. Immunoglobulin gene rearrangement confirmed monoclonalility. Tetraploidy of the clone and del(17)(p11) have been previously described only in a cell line or at end stage disease in B-ALL. It is suggested that the chromosomal abnormalities present at diagnosis were directly related to the refractory nature of this leukemia.

Leukemia diagnosis and testing of complement-fixing antibodies for bone marrow purging in acute lymphoid leukemia

In this paper a microplate method is described for diagnosing acute leukemia and for investigating the reactivity of monoclonal antibodies (MoAbs) against membrane antigens in combination with rabbit or murine antibodies to nuclear terminal transferase (TdT). The speed of this method facilitates the investigation of fresh leukemic cells from individual patients and assesses the cytolytic efficacy of the relevant MoAbs in the presence of complement (C'). Lymphoblasts (TdT+) are mixed in equal proportions with known numbers of "inert" cells, eg, RBC or nonleukemic bone marrow (BM). Following incubation with MoAbs and C' the ratio of residual TdT+ cells and inert cells is determined on cytospin preparations. Initially, percentages of TdT+ cells are counted in a unit volume of 5,000 inert cells, followed by the scanning of greater than 2 X 10(4) inert cells on entire slides. With this method more than 4 log cytoreduction of TdT + cells is detected. The method is also applicable for studying the cytolysis of malignant B cells by using mostly monoclonal lg expression rather than TdT for the identification of residual B cells. Ten representative patients selected from a group of greater than 100 are reported. In some cases cytoreduction of greater than 4 log with no identifiable residual TdT + cells is achieved by a single C'-fixing MoAb: anti-CD10 (RFAL3) in common acute lymphoid leukemia (ALL) and anti-CD7 (RFT2) in T cell ALL (T-ALL). Other cases require cocktails of anti-CD10, anti-CD19, and anti-CD24 in common ALL or anti-CD7 and anti-CD8 in T-ALL. In T-ALL a few TdT + cells remain that exhibit the features of normal TdT + BM cells (CD7-, HLA-DR+). This is particularly noticeable when patients are studied in partial remission or if nonleukemic BM is used as a source of inert cells. The methods described here contribute to establishing a range of MoAbs (ie, of IgM class) and techniques for efficient purging and to comparing the efficacy of "clean-up," in remission, of common ALL, T-ALL, and B cell malignancies.

Human leukocyte function-associated antigens on lympho-hemopoietic precursor cells

The expression of human leukocyte function-associated antigens (HLFA, equivalents of murine LFA-1) was studied on early lympho-hemopoietic cells in infant thymus and normal bone marrow by double immunofluorescence methods, cell sorting and colony-forming assays. Monoclonal antibodies MHM-24 recognizing the alpha chain (180 kDa) and 60.3 and 60.1 identifying the beta chain (95 kDa) were used. The vast majority of thymocytes including large terminal deoxynucleotidyl transferase (TdT)-positive blast cells are HLFA positive. On the other hand, most B cell precursors in the bone marrow, identified by the expression of nuclear TdT, do not show surface HLFA which appears at the pre-B cell stage (cytoplasmic mu positive, surface Ig negative). Cell sorting experiments revealed an enrichment of early myeloid cells (myeloblasts and colony-forming unit cells) in the HLFA-negative fraction. Erythroid cells appeared to be completely negative from the burst-forming unit erythrocyte stage onwards. Anti-HLFA-antibodies, capable of blocking T cell and natural killer function, may have therapeutic potential without interfering with precursor cell development in man.

T lymphocyte regeneration after transplantation of T cell depleted allogeneic bone marrow

The regeneration of T cell subsets was studied with double immunofluorescence marker methods in 37 patients who received HLA matched T lymphocyte depleted bone marrow transplants (BMT) as part of the treatment for their haematological disease. A cocktail of anti-pan-T (CD6: MBG6) and anti-suppressor/cytotoxic-T cell (CD8: RFT8) monoclonal antibodies was used with rabbit serum as a source of cytolytic complement to achieve selective T cell lysis. The T8+ cells reached low normal values around 60 days post-transplant and remained within the normal range throughout the study (greater than 150 days). This observation is in contrast to our previously published results in patients who, after receiving BMT without efficient T cell depletion, had increased numbers of circulation T8+ cells from 60 days post-transplant. In the present study Leu-7+, RFT8- cells reached normal values rapidly but the reconstitution of T4+ lymphocytes was slow: low normal levels were reached only around day 150 following BMT. The degree of graft-versus-host disease (GVHD) seemed to be related to the number of residual T cells infused: two of the three patients who received the highest numbers of T cells developed Grade II III; otherwise GVHD was minimal. Among the clinical parameters studied cytomegalovirus (CMV) immune status moderately influenced reconstitution: at 55-90 days post-transplant T8+ cells were present at the upper normal levels in seven out of 15 patients receiving BMT from CMV seronegative donors, but in none of the 16 individuals receiving BMT from seropositive donors. CMV related complications were relatively uncommon. Thus the most significant factor in preventing 'T8+ cell overshoot' and T cell imbalance during regeneration appears to be the depletion of T (including T8+) lymphocytes from marrow. The differences of T8+ cell reconstitution in this and previous studies may reflect a different regeneration pattern from T cell precursors as opposed to inoculated mature T cells.