Leukemic Cells In Peripheral Blood Research Articles

Purification and characterization of deoxycytidine kinase from acute myeloid leukemia cell mitochondria

Deoxycytidine kinase is a key anabolic enzymes for the activation of ara-C and other antitumor drugs, as well as normal purine and pyrimidine deoxynucleosides. Previously, two forms of the kinase have been identified; deoxcycytidine kinase I (70 kDa) and deoxycytidine kinase II (70 kDa). Deoxycytidine kinase I utilized dCyd and ara-C as substrates, while deoxycytidine kinase II used dCyd and dThd as substrates. Deoxycytidine kinase kinase II had very low activity on ara-C as a substrate. We report a procedure for the purification of a novel deoxycytidine kinase (52 kDa) from isolated human peripheral blood leukemia cell mitochondria. This enzyme has activity similar to deoxycytidine kinase II. The enzyme was extracted from the mitochondria with digitonin (1 mg/8 protein) and 0.3 M NaCl, and the extract was purified by DEAE-cellulose chromatography and thymidine-Sepharose affinity chromatography. This procedure produced a near homogenous enzyme preparation with a yield of 70%. The mitochondrial deoxycytidine kinase was localized to the outer mitochondrial membrane. The enzyme phosphorylated dCyd ( K m = 17 μM), however, ara-C was not a good substrate for the mitochondrial deoxycytidine kinase. ATP was the best phosphate donor, whreas dCTP and dTTP were potent inhibitors of mitochondrial deoxycytidine kinase. In contrast, phosphorylation of ara-C by deoxycytidine kinase I utilized GTP, dGTP, or ATP as a phosphate donor.

E-selectin and vascular cell adhesion molecule-1 mediate adult T-cell leukemia cell adhesion to endothelial cells

We studied the adhesion properties of peripheral blood leukemic cells from 10 patients with adult T-cell leukemia (ATL) to endothelial cells to better understand the mechanism of leukemic cell infiltration. ATL cells expressed lymphocyte function-associated antigen-1 (LFA-1), but the expression of very late antigen-4 (VLA-4) and sialyl-Lewisx (SLex) was variable. They did not express sialyl-Lewisa (SLea). Cell adhesion assays, which were performed in nine patients, showed marked adhesion of ATL cells to interleukin [IL]-1-activated human umbilical vein endothelial cells (HUVEC). A monoclonal antibody (MoAb) against E- selectin consistently inhibited ATL cell adhesion, and an MoAb against vascular cell adhesion molecule-1 (VCAM-1) or an MoAb against VLA-4 sometimes diminished it. In contrast, an MoAb against LFA-1 had a minor effect on freshly isolated ATL cell adhesion to HUVEC. The percentage of SLex+ cells in the cell population adherent to IL-1-activated HUVEC was slightly higher than that in unseparated cells. These results, together with the detection of E-selectin expression on the endothelium at ATL skin lesions, indicate that E-selectin-mediated adhesion is the major pathway for the adherence of ATL cells to endothelial cells. In addition, the ligand for E-selectin on ATL cells appears to differ from that on neutrophils.

E-Selectin and Vascular Cell Adhesion Molecule-1 Mediate Adult T-Cell Leukemia Cell Adhesion to Endothelial Cells

AbstractWe studied the adhesion properties of peripheral blood leukemic cells from 10 patients with adult T-cell leukemia (ATL) to endothelial cells to better understand the mechanism of leukemic cell infiltration. ATL cells expressed lymphocyte function-associated antigen-1 (LFA-1), but the expression of very late antigen-4 (VLA-4) and sialyl-Lewisx (SLex) was variable. They did not express sialyl-Lewisa (SLea). Cell adhesion assays, which were performed in nine patients, showed marked adhesion of ATL cells to in-terleukin [IL]-1-activated human umbilical vein endothelial cells (HUVEC). A monoclonal antibody (MoAb) against E-selectin consistently inhibited ATL cell adhesion, and an MoAb against vascular cell adhesion molecule-1 (VCAM-1) or an MoAb against VLA-4 sometimes diminished it. In contrast, an MoAb against LFA-1 had a minor effect on freshly isolated ATL cell adhesion to HUVEC. The percentage of SLex+ cells in the cell population adherent to IL-1 -activated HUVEC was slightly higher than that in unsepa-rated cells. These results, together with the detection of E-selectin expression on the endothelium at ATL skin lesions, indicate that E-selectin-mediated adhesion is the major pathway for the adherence of ATL cells to endothelial cells. In addition, the ligand for E-selectin on ATL cells appears to differ from that on neutrophils.

Derivative (11)t(7;11)(q11;q24) in a child with acute megakaryoblastic leukemia

We document the clinical, morphologic, and cytogenetic findings in a 2 1 2 -year-old patient with acute megakaryoblastic leukemia. Cytogenetic analysis of peripheral blood leukemic cells revealed the presence of a der(11)t(7;11)(q11;q24). Chromosome 7 involvement is observed in nearly half of all cases of megakaryoblastic leukemias, however, the type of abnormality differs widely from one case to another. The der(11)t(7;11)(q11;q24) described here is the first reported to our knowledge.

Effects of granulocyte-macrophage colony-stimulating factor and interleukin 6 on the growth of leukemic blasts in suspension culture.

We examined the stimulatory effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 6 (IL)-6 on the in vitro proliferation of leukemic blast cells from patients with acute leukemia. Bone marrow or peripheral blood leukemic blast cells were obtained from 21 patients, including 14 cases of acute myeloblastic leukemia (AML), four cases of acute lymphoblastic leukemia (ALL), two cases of acute undifferentiated leukemia, and one case of acute mixed-lineage leukemia. The proliferation of leukemic blast cells was evaluated by measuring the incorporation of 3H-thymidine into cells incubated with various concentrations of cytokines for 3 days. GM-CSF stimulated the DNA synthesis (with greater than 2.0 stimulation index) of blast cells in 9 of 14 (64%) AML cases, two cases of acute undifferentiated leukemia and one case of acute mixed-lineage leukemia. Only two cases of AML blasts responded to IL-6 to grow in the short-term suspension cultures. GM-CSF and IL-6 did not display a synergistic effect on the growth of leukemic cells. Moreover, GM-CSF and IL-6 did not stimulate the proliferation of ALL blast cells. Binding study also revealed the specific binding of GM-CSF on the blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia. Our results indicated that leukemic blast cells of acute undifferentiated leukemia and acute mixed-lineage leukemia possessed functional GM-CSF receptors.

EXPERIMENTAL STUDIES ON MINIMAL RESIDUAL LEUKEMIA

Using a transplantable mouse leukemia (L7212) , a T-cell ALL, a similar model to human minimal residual leukemia was reproduced. At the 3rd day after inoculation of S.C. 1.0 ×106 cells, the mice were injected i.p. with a single high dose of cyclophosphamide (250mg/kg) . The mice treated with CTX survived longer time, number of leukemia cells remained in the body was the lowest, and the rate of leukemia relapse was the highest. The results were quite stable. Therefore, this model could be used to study minimal residual leukemia. According to the detection of residual leukemia cells in the spleen, liver and peripheral blood, the distribution of residual leukemia cells was not homologous. The migration of leukemia cells from local organs to circulation blood was very rapid. The count of WBC in peripheral blood and the weight of liver and spleen in the relapsed leukemia was higher than that of non-treated leukemia mice, and the G0 + Gl phase cells of relapsed leukemia was also higher. It was helpful for studying human residual leukemia. Key words: Mouse leukemia; minimal residual leukemia; leukemia relapse

Establishment and characterization of a new human leukemia cell line derived from M4E0

A new human leukemia cell line, designated as ME-1, was established from the peripheral blood leukemia cells of a patient with acute myelomonocytic leukemia with eosinophilia (M4E0). This cell line has the characteristic chromosome abnormality of M4E0, inv(16) (p13q22). When cultured in RPMI 1640 medium containing 10% fetal calf serum, ME-1 cells were monoblastoid, but with the addition of cytokines such as interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4, or medium conditioned by phytohemagglutinin-stimulated human peripheral leukocytes (PHA-LCM), the cells exhibited differentiation to macrophage-like cells. PHA-LCM also promoted eosinophilic-lineage differentiation of this cell line, although IL-5 did not do so. To elucidate the mechanism of proliferation and differentiation of ME-1 cells, we studied the effect of a potent inhibitor of protein kinase C, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7), on colony formation of ME-1 cells. H-7 inhibited colony formation of ME-1 cells by IL-3 or GM-CSF dose dependently, but had little inhibitory effect on colony formation by IL-4. These results indicate that the proliferation and differentiation of ME-1 cells by IL-3 or GM-CSF were related to the activation of protein kinase C, while those by IL-4 involved other regulatory systems. ME-1 cells should be useful for studying the pathogenesis of M4E0 and the mechanisms of proliferation and differentiation of leukemic and normal progenitors by cytokines.

Establishment and Characterization of a New Human Leukemia Cell Line Derived From M4E0

Abstract A new human leukemia cell line, designated as ME-1, was established from the peripheral blood leukemia cells of a patient with acute myelomonocytic leukemia with eosinophilia (M4E0). This cell line has the characteristic chromosome abnormality of M4E0, inv(16) (p13q22). When cultured in RPMI 1640 medium containing 10% fetal calf serum, ME-1 cells were monoblastoid, but with the addition of cytokines such as interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-4, or medium conditioned by phytohemagglutinin-stimulated human peripheral leukocytes (PHA-LCM), the cells exhibited differentiation to macrophage-like cells. PHA-LCM also promoted eosinophilic-lineage differentiation of this cell line, although IL-5 did not do so. To elucidate the mechanism of proliferation and differentiation of ME-1 cells, we studied the effect of a potent inhibitor of protein kinase C, 1-(5-isoquinolinyl-sulfonyl)-2- methylpiperazine (H-7), on colony formation of ME-1 cells. H-7 inhibited colony formation of ME-1 cells by IL-3 or GM-CSF dose dependently, but had little inhibitory effect on colony formation by IL- 4. These results indicate that the proliferation and differentiation of ME-1 cells by IL-3 or GM-CSF were related to the activation of protein kinase C, while those by IL-4 involved other regulatory systems. ME-1 cells should be useful for studying the pathogenesis of M4E0 and the mechanisms of proliferation and differentiation of leukemic and normal progenitors by cytokines.

SPECIFIC RECOGNITION OF HUMAN LEUKEMIC CELLS BY ALLOGENEIC T CELL LINES

Clinical and experimental data suggest a role for the immune response in preventing leukemic relapses following allogeneic bone marrow transplantation the graft-versus-leukemia (GVL) effect. In the context of an allogeneic BMT, a number of different immune mechanisms mediated by donor cells may be responsible for the GVL effect. We have approached this question by using limiting dilution cultures of alloactivated human lymphocytes to analyze the in vitro allogeneic cytolytic response against fresh allogeneic leukemia. Initial results in the limiting dilution assays with split culture analyses demonstrated frequent alloreactive cytolytic T lymphocyte precursors that destroyed remission peripheral blood lymphocytes and leukemic cells from the allogeneic leukemic patient. These assays also demonstrated frequent lymphokine-activated killer (LAK) cell precursors that lysed both the LAK sensitive Daudi line and the allogeneic leukemia. In these experiments, isolated cultures also showed cytolytic activity directed against the allogeneic leukemic blasts without activity against remission PBL, or the LAK-sensitive Daudi cell line. Two T cell lines (ABL1 and ABL2) isolated from an LDA, demonstrated this form of specificity, mediating destruction specifically against the allogeneic acute lymphoblastic leukemic cells. Both cell lines ABL1 and ABL2 were CD3+, TCR alpha beta +, and CD4+. These 2 cell lines mediated little or no cytotoxicity against a large panel of other targets tested (natural killer sensitive and resistant cell lines, allogeneic PBL, and allogeneic fresh leukemic blasts). Antibody-blocking experiments revealed a role for the CD3-TCR receptor of both cell lines in lysis of leukemic cells; the CD4 and MHC class II molecules were clearly involved in the lysis by the ABL1 cell line. Specificity of recognition for the allogeneic leukemic blasts was further confirmed by unlabeled target competitive inhibition studies. The mechanism of the preferential lysis of leukemia by the alloactivated T cell lines described in this paper remains uncertain. Nevertheless, these leukemic-specific populations provide a means by which the human GVL effect may be further studied in vitro.

Elevated serum-soluble interleukin-2 receptor (Tac antigen) levels in chronic myelogenous leukemia patients with blastic crisis

We examined the expression of cell-surface interleukin-2 (IL-2) receptor (Tac antigen) on peripheral blood leukemic cells and measured soluble IL-2 receptor p55(alpha) chain (sIL-2R) levels in sera from chronic myelogenous leukemia (CML) patients with blastic crisis. Flow cytofluorometric analysis performed by dual immunofluorescence in three cases demonstrated coexpression of Tac antigen with myeloid (CD13, CD14, or CD33) or lymphoid (CD10) antigen on significant proportions of peripheral blood leukemic cells. Radiolabeled IL-2-binding assay demonstrated the specific IL-2 binding sites in three cases examined. The exogenous IL-2, however, failed to induce proliferative response. A myeloid cell line, Yut-K3, established from peripheral blood leukemic cells from a CML patient with blastic crisis, also expressed cell- surface Tac antigen and CD13 concurrently. SIL-2R assay showed that Yut- K3 released a detectable amount of sIL-2R in its culture supernatant. The serum sIL-2R levels were significantly elevated (range: 2,580 to 172,000 U/mL) in 12 CML patients with blastic crisis and were slightly elevated in ten patients in chronic phase (range: 250 to 820 U/mL) and in three in accelerated phase (range: 790 to 1,305 U/mL) compared with those in 24 normal controls (range: 70 to 695 U/mL, P less than .01). These results indicated that the leukemic cells from CML patients with blastic crisis expressed and released IL-2 receptor (Tac antigen). Longitudinal studies performed in three cases of CML with blastic crisis showed that the change of serum sIL-2R level was closely associated with that of the number of peripheral blood leukocytes and blasts, the percentage of blasts and serum LDH levels, also suggesting that the serum sIL-2R level is a useful clinical indicator of the leukemic cell burden in vivo.

Elevated Serum-Soluble Interleukin-2 Receptor (Tac Antigen) Levels in Chronic Myelogenous Leukemia Patients With Blastic Crisis

AbstractWe examined the expression of cell-surface interleukin-2 (IL-2) receptor (Tac antigen) on peripheral blood leukemic cells and measured soluble IL-2 receptor p55(alpha) chain (sIL-2R) levels in sera from chronic myelogenous leukemia (CML) patients with blastic crisis. Flow cytofluorometric analysis performed by dual immunofluorescence in three cases demonstrated coexpression of Tac antigen with myeloid (CD13, CD14, or CD33) or lymphoid (CD10) antigen on significant proportions of peripheral blood leukemic cells. Radiolabeled IL-2-binding assay demonstrated the specific IL-2 binding sites in three cases examined. The exogenous IL-2, however, failed to induce proliferative response. A myeloid cell line, Yut-K3, established from peripheral blood leukemic cells from a CML patient with blastic crisis, also expressed cell-surface Tac antigen and CD13 concurrently. SIL-2R assay showed that Yut-K3 released a detectable amount of sIL-2R in its culture supernatant. The serum sIL-2R levels were significantly elevated (range: 2,580 to 172,000 U/mL) in 12 CML patients with blastic crisis and were slightly elevated in ten patients in chronic phase (range: 250 to 820 U/mL) and in three in accelerated phase (range: 790 to 1,305 U/mL) compared with those in 24 normal controls (range: 70 to 695 U/mL. P< .01). These results indicated that the leukemic cells from CML patients with blastic crisis expressed and released IL-2 receptor (Tac antigen). Longitudinal studies performed in three cases of CML with blastic crisis showed that the change of serum sIL-2R level was closely associated with that of the number of peripheral blood leukocytes and blasts, the percentage of blasts and serum LDH levels, also suggesting that the serum slL-2R level is a useful clinical indicator of the leukemic cell burden in vivo.

Direct and serial transplantation of Ph1‐positive acute lymphoblastic leukemia into nude mice

A new Philadelphia chromosome (Ph1-positive) acute lymphoblastic leukemia (ALL) cell line was established in nude mice by direct and serial transplantation of peripheral blood leukemia cells from an adult patient. Although the patient's leukemia cells did not grow in vitro, they were successfully transplanted for 8 serial passages, giving rise to progressive growth of tumors with frequent involvement of lymph nodes, liver, spleen, bone marrow, and meninges. The tumor cells could also be passaged in an ascites form. This in vivo cell line, designated PALL-I, retained the Ph1 chromosome, t(9;22) (q34;q11), and pre-B-cell phenotype (SmIg-, CpIg-, CD10+, CD19+, OKIaI+, and CD38+), like the original leukemia cells. Molecular genetic analysis of PALL-I cells revealed neither bcr rearrangement nor 8.5-kb abI-related mRNA that is characteristically seen in Ph1-positive chronic myelogenous leukemia (CML). Thus, the PALL-I cell line is genetically distinct from CML. It may provide a useful model for an understanding of the cellular and molecular biology of Ph1-positive ALL without classical bcr rearrangement.

Analysis of peroxidase negative acute leukemias by monoclonal antibodies: III. Acute lymphoblastic leukemia.

Peripheral-blood leukemic cells from 45 patients with peroxidase negative acute lymphoblastic leukemia (ALL), which did not express either myeloid or megakaryocyte-platelet-related cell surface antigens, were analyzed by using monoclonal antibodies capable of recognizing T- or B-cell-associated and/or T- or B-cell-restricted antigens. Numerous subclasses of ALL, including B-cell lineage leukemias and T-cell lineage leukemias, were identified phenotypically and immunophenotypically in an effort to more accurately characterize the heterogeneous ALLs, their states of differentiation, and their relationships to normal B- and T-lymphoid cells. Among the cases studied, only seven (15.6%) were found to have stem cell (undifferentiated) leukemia (Ia+, CD24+, CD9+, CD34+). It is concluded that the use of monoclonal antibodies for the characterization of heterogeneous ALLs improves the specificity of leukemia classification, which may contribute to the selection of more effective forms of therapy for the types of leukemia identified.

Leukemic cells from some adult T-cell leukemia patients proliferate in response to interleukin-4

The proliferative response of fresh peripheral blood leukemic cells from eight adult T cell leukemia (ATL) patients to interleukin-4 (IL-4) was studied to determine the possibility that the IL-4-mediated T-cell growth pathway is involved in the cell growth of leukemic cells in ATL. Resting lymphocytes from ten normal individuals did not proliferate in response to IL-4. Leukemic cells from two ATL patients did not respond to interleukin-2 (IL-2) or IL-4. Leukemic cells from two patients did respond to IL-2, but not to IL-4. In contrast, a strong proliferative response was observed in the IL-4 culture, but not in the IL-2 culture in the remaining four patients. Chromosome analysis of mitotic cells, performed in one of four patients, confirmed that the cells dividing in response to IL-4 were leukemic cells, but not activated normal lymphocytes. These results indicate the activation of IL-4/IL-4 receptor system in leukemic cells from some ATL patients and suggest the possible involvement of the system in the proliferation of leukemic cells and the leukemogenesis in ATL.

Increase in cytoplasmic free calcium concentration initiated by T3 antigen stimulation is imparied in adult T-cell leukemia cells

We studied the change in cytoplasmic free calcium ion concentration ([Ca 2+] i) in the peripheral blood leukemic cells from adult T-cell leukemia (ATL) patients stimulated by anti-T3(CD3) or anti-T11(CD2) antibodies in order to see whether there is an abnormal response in the early activation processes following T3 or T11 antigen stimulation. Peripheral blood mononuclear cells (PBMC) from four T-cell chronic lymphocytic leukemia (T-CLL) patients showed a rapid and clear increase in [Ca 2+] i (from 165 ± 26 nM to more than 299 nM) when stimulated by OKT3 antibody and anti-mouse IgG antibody. This response was comparable to that of PBMC from 10 normal individuals (from 151 ± 20 nM to 252 ± 34 nM). In contrast, PBMC from 10 ATL patients showed only a slight increase in [Ca 2+] i (from 137 ± 21 nM to 176 ± 32 nM) following T3 stimulation. The experiments with higher concentrations of OKT3 antibody suggested that this attenuated increase in [Ca 2+] i in ATL cells was not exclusively due to impaired expression of T3 antigen. The [Ca 2+] i increase in ATL cells induced by the stimulation with two anti-T11 antibodies recognizing different epitopes of the T11 antigen, however, was comparable to that of normal PBMC. The abnormal response of [Ca 2+] i to the T-cell receptor /T3 antigen stimulation in ATL may be related to dysfunction or leukemogenesis of HTLV-I-infected cells.

Enhancement of etoposide-induced cytotoxicity by cyclosporin A.

Following the clinical observation of enhanced antineoplastic action of etoposide in the presence of cyclosporin A (CyA), we investigated this drug interaction in several in vitro and in vivo tumor systems. Macromolecular DNA damage induced by etoposide at drug levels comparable to plasma AUC values achieved in patients was increased not only in leukemic peripheral blood cells from patients but also in mononuclear peripheral blood cells from a healthy donor. Intracellular retention of radioactivity from 3H-etoposide was increased by a factor of 1.5 at the most in the presence of CyA. The cytotoxicity of etoposide and adriamycin to L 1210 leukemic cells was clearly enhanced, whereas CyA had no effect on the action of cisplatin or ionizing irradiation. At CyA blood levels not exceeding 1.44 microgram/ml, increased tumor inhibition of etoposide was observed in a human embryonal cancer xenograft, but there was also higher lethality in normal mice. We conclude from our own data and from other recent findings that with respect to chemosensitization the effects of CyA resemble those of calcium channel blockers or anticalmodulin agents. In contrast to calcium channel blockers, however, adequate plasma levels of CyA can well be achieved in patients.

9-?-D-Arabinofuranosyl-2-fluoroadenine 5?-monophosphate pharmacokinetics in plasma and tumor cells of patients with relapsed leukemia and lymphoma

The pharmacokinetics of 9-beta-D-arabinofuranosyl-2-fluoroadenine (F-ara-A) in plasma and its biologically active 5'-triphosphate (F-ara-ATP) in leukemic cells obtained from the peripheral blood and bone marrow was evaluated in patients with hematologic malignancies subsequent to the first dose of 20-125 mg/m2 per day for 5 days of F-ara-A 5'-monophosphate (F-ara-AMP) administered as an IV bolus over 30 min. The terminal half-lives of elimination of both F-ara-A (8 h) in plasma and intracellular F-ara-ATP (15 h) were not dependent upon the dose of F-ara-AMP. The area under the concentration X time curves for F-ara-A and F-ara-ATP, on the other hand, were increased in proportion to the prodrug dose. There was a high correlation between F-ara-ATP levels in circulating leukemic cells and those in bone marrow cells aspirated at the same time. DNA-synthetic capacity of leukemic cells was inversely related to the associated F-ara-ATP concentration. A linear trend was noted when F-ara-ATP levels in pretreatment peripheral blood leukemic cells incubated with F-ara-A in vitro were compared with the amount of F-ara-A that was incorporated into nucleic acids. Finally, F-ara-ATP concentrations were three times higher in bone marrow cells from patients with lymphomatous bone marrow involvement than from those without evidence of marrow disease.

Analysis of neoplastic leukocyte surface antigens in unfractionated blood.

The detection of leukemic cells in peripheral blood is based on cytologic and cytochemical methods. Recently, the characterization of leukemic cells has been improved by the analysis of cell surface antigens. Abundant leukemic cells are relatively easy to identify. Small numbers of circulating leukemic cells, however, may be difficult to recognize by conventional or immunological techniques. This is of particular importance in treated patients in whom the presence of low levels of circulating leukemic cells may have considerable clinical relevance. We used multiparameter correlated flow cytometric analysis to detect and characterize human leukemia/lymphoma cells in small samples of unfractionated peripheral blood. Leukocyte surface antigens were labeled with monoclonal antibodies and simultaneous forward and right-angle light scatter and fluorescence signals were measured from each cell. An interactive computer program was written that permitted the two light scatter measurements to be displayed on the screen on a cell-by-cell basis (dot-plot). Subpopulations of interest could then be selected on the dot-plot for analysis of their fluorescence distribution. On the basis of their dual scatter properties and their antigenic profile, neoplastic leukocytes were recognized even in cases in which leukemic cells were infrequent and not detectable by conventional cytologic methods.

Phenotypic and Ultrastructural Profile of M5 Leukemia Cells in Peripheral Blood and Skin Infiltrate

The leukemic cells circulating in the peripheral blood and invading the skin of a patient with type M5 myelomonocytic leukemia were compared using ultrastructural, cytochemical and immunological criteria. Neoplastic cells exhibited more differentiated morphologic features in the skin than in peripheral blood, resembling tissue macrophages. The cytochemical pattern did not show any appreciable difference, whereas the surface antigenic profile was dissimilar. Most circulating leukemic cells were Leu M1+ and Leu M3+, and the percentage of OKM1+ and OKIa-1+ cells varied in two different blood samples examined. Conversely, OKIa-1 monoclonal antibody stained virtually all the leukemic cells infiltrating the skin in the absence of any appreciable reactivity with the other monoclonal antibodies. The phenotype of the malignant cells in the skin did not vary during the clinical course of the disease. These observations suggest that the cutaneous microenvironment is able to induce leukemic cells to mutate their phenotypic features towards a more mature state, or that only relatively differentiated circulating leukemic cells are able to leave the bloodstream and colonize the skin.

Expression of interleukin-2 receptor on T cell chronic lymphocytic leukemia cells and their response to interleukin-2

We analyzed peripheral blood leukemic cells from six patients with T cell chronic lymphocytic leukemia (T-CLL) with monoclonal antibodies including the anti-Tac antibody, which recognizes the receptor for interleukin 2 (IL 2). The patients were divided into two groups according to the reactivity of the monoclonal antibodies. Leukemic cells from three patients with T-CLL reacted with OKT3 and T4 but not T8, whereas those from the remaining three patients reacted with OKT3 and T8 but not T4. IL 2 receptor, which is expressed on activated T cells but not on resting T cells, was preferentially expressed on T4+ T-CLL cells. The IL 2 receptor on T4+ T-CLL cells was indistinguishable from that on normal activated T cells with respect to molecular weight and downregulation by the anti-Tac antibody. Moreover, fresh T4+ T-CLL cells, but not T8+ T-CLL cells, proliferated in response to exogenous IL 2 without prior activation, and this proliferation was inhibited by the anti-Tac antibody. These results suggest that malignant growth of T4+ T-CLL cells can be regulated by IL 2 not only in vitro but also in vivo.