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J Ritz

Publications and source records attributed to J Ritz.

At least 199 records · Page 11Linked to original sources
PubMed1985

Functional characterization of LFA-1 antigens in the interaction of human NK clones and target cells.

In the present studies we analyzed the role of LFA-1 antigens in the interaction between NK clones and target cells. The use of various cloned NK cell lines allowed us to analyze homogeneous populations of NK cells which ordinarily comprise only a small fraction of peripheral blood lymphocytes and are extremely heterogeneous with respect to phenotype and specificity. Indirect immunofluorescence with monoclonal antibodies against the alpha (MHM24) and beta (MHM23) chains of the LFA-1 antigen revealed similar patterns of positive reactivity with all NK clones. Both monoclonal antibodies exerted a significant blocking effect on NK cytotoxicity against target cells such as Molt-4 and CEM, whereas the inhibition was very weak against other targets such as K562 and HSB cells. Additive blocking effects were seen when both monoclonal antibodies MHM23 and MHM24 were added to the cytotoxicity assays. When we compared the inhibitory effect of MHM23 and MHM24 on uncultured peripheral blood NK cells and IL 2-activated NK cells, inhibition of cytotoxicity also was found to be primarily dependent on the individual target cells. Thus, the inhibitory activity of anti-LFA-1 antibody was shown to be independent of the phenotypic and functional heterogeneity of the NK clones, activated NK cells, and unstimulated NK cells utilized in these studies. These blocking effects were found to be independent of the LFA-1 antigen expression on the target cell membrane and inhibition occurred only when antibody was bound to the effector cells. Comparison of the effects of anti-LFA-1, anti-T3, and anti-clonotypic antibodies against a Ti-like structure of different NK clones with a mature T cell phenotype demonstrated that each of these antibodies acts on the effector cells in an independent and additive fashion. However, unlike T3 and NKTa antigen, LFA-1 antigen expression is not modulated by cell surface interaction with antibodies specific for this molecule.

Antibodies, Monoclonal↗
PubMed1985

Elimination of malignant clonogenic cells from human bone marrow using multiple monoclonal antibodies and complement.

A clonogenic assay has been developed that utilizes Burkitt's lymphoma tumor cell lines to detect elimination of up to 5 logs of tumor cell contamination within human bone marrow. Different Burkitt's lymphoma lines bear one or more of a group of markers, including common acute lymphoblastic leukemia antigen gp26 (glycoprotein with a molecular weight of 26,000), B1, surface membrane immunoglobulin, HLA, beta 2-microglobulin, and Ia. Burkitt's tumor cells of the Namalwa line have been mixed with a 20-fold excess of irradiated human bone marrow cells. After treatment with one or more monoclonal antibodies and rabbit complement (RC), mixtures have been grown on a monolayer of irradiated human bone marrow cells and tumor cells enumerated by limiting dilution. Multiple treatments with antibody and RC were more effective than a single treatment in destroying clonogenic tumor cells which bore relevant determinants. Human serum components inhibited the lytic activity of RC in the presence of murine monoclonal antibodies. The total concentration of bone marrow cells proved critical in determining the complete elimination of tumor. Incubation of the Namalwa tumor cell line with RC and the J2 anti-gp26 eliminated more than 3 logs of malignant cells from a 20-fold excess of human bone marrow. Combinations of two monoclonal antibodies were more effective than any single antibody in eliminating Namalwa cells. A combination of three monoclonal reagents was no more effective than a combination of J2 and B1 or J2 and J5 in eliminating Namalwa cells. Treatment of human bone marrow with three antibodies and RC did not, however, produce a selective loss of nonmalignant GM-CFU-C, CFU-E, or BFU-E.

Antibodies, Monoclonal↗
PubMed1985

Effects of monoclonal antibody and complement treatment of human marrow on hematopoiesis in continuous bone marrow culture.

Long-term bone marrow cultures were established from single-cell suspensions of human bone marrow that had been treated with monoclonal antibodies and complement. Each treated cell suspension was evaluated for production of hematopoietic stem cells over 20 weeks. Treatment with antibody to HLA-DR (Ia), B1, J2, or J5 did not remove adherent cells including those differentiating to adipocytes in 17-hydroxycorticosteroid. In contrast, treatment with monoclonal antibody directed against human beta 2-microglobulin reduced adipocyte numbers by 100-fold and reduced the total adherent cell density over 70%. Cumulative total nonadherent cell and granulocyte-macrophage colony-forming units (GM-CFUc) production over 20 weeks was not significantly altered by one cycle of anti-Ia plus complement or up to three cycles of treatment with complement and anti-J2, -J5, or -B1. However, one cycle of treatment with anti-beta 2-micro-globulin depressed production of both GM-CFUc and nonadherent cells by over 100-fold compared to other treatment groups. While one cycle of treatment of anti-Ia and complement killed all detectable cells forming CFU-erythroid-granulocyte-megakaryocyte-macrophage, blast-forming units (erythroid), and GM-CFUc, GM cluster-forming cells survived. Treatment of marrow with three cycles of anti-Ia and complement removed all detectable GM colony- and GM cluster-forming cells; however, this marrow produced fewer cumulative Ia-positive GM-CFUc. Long-term bone marrow cultures may prove to be an interesting system for in vitro analysis of the effects of new immunotherapeutic agents including other monoclonal antibodies prior to clinical use.

Adipose Tissue↗
PubMed1985

Elimination of clonogenic Burkitt's lymphoma cells from human bone marrow using 4-hydroperoxycyclophosphamide in combination with monoclonal antibodies and complement.

One requirement for autologous bone marrow transplantation is the selective removal of malignant cells from normal marrow precursors. Development of a clonogenic assay that detects elimination of up to 5 logs of Burkitt's lymphoma cells in the presence of a 20-fold excess of human bone marrow has permitted the evaluation of two different methods for the selective removal of malignant cells. Treatment with 4-hydroperoxycyclophosphamide (4-HC) (60 to 100 micrograms/mL) eliminated 2.0 to 3.5 logs of clonogenic cells. Antitumor activity depended upon the concentration of 4-HC and the length of incubation, but not upon the concentration of normal bone marrow cells. Comparable removal of clonogenic Burkitt's cells was achieved by treatment with rabbit complement (C') and a combination of J5 anti-common acute lymphoblastic leukemia antigen (J5 anti-CALLA), J2 anti-gp 26, and the B1 anti-B1 murine monoclonal antibodies. A combination of 4-HC and monoclonal antibodies proved slightly but significantly more effective than either single agent in eliminating clonogenic tumor cells. Although treatment with 4-HC markedly reduced granulocyte-macrophage colony-forming units-C (GM-CFU-C) content of human bone marrow, neither treatment with 4-HC nor treatment with monoclonal antibodies and C' eliminated precursor cells that could generate new GM-CFU-C after growth in continuous bone marrow cultures. Our data suggest that treatment with 4-HC in combination with multiple monoclonal antibody reagents could be a safe and effective method of eliminating clonogenic tumor cells from human bone marrow.

Antibodies, Monoclonal↗
PubMed1984

Identification of a 140-kDa activation antigen as a target structure for a series of human cloned natural killer cell lines.

In the present study, we have developed a monoclonal antibody termed anti-TNKTAR, able to block cytotoxicity mediated by a human natural killer (NK) clone termed JT9. Analysis of the functional effects of anti-TNKTAR indicated that alteration of the cytotoxic reactions resulted from the binding of the antibody to the membrane of target cells. In addition, it was shown that inhibition of cytotoxicity induced by anti-TNKTAR could be abolished by lectin approximation. Immunoprecipitation experiments indicated that TNKTAR antigen is a heterodimeric structure which resolves as a single band at 140 kDa under nonreducing conditions and as two bands at approximately 97 kDa and 40 kDa under reducing conditions in sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. This heterodimer is present on lymphocytes and monocytes in human peripheral blood and perhaps more importantly, the membrane density of TNKTAR antigen increases very early and strongly following lymphocyte activation. In addition, it was shown that TNKTAR is expressed on each single cultured cell line which has been tested, although the density of the antigen varies strongly from one cell line to another. Even though the 140-kDa molecule was found to be widely distributed on activated cells, anti-TNKTAR had no blocking effects on cytotoxic reactions mediated by a series of either NK or cytotoxic T lymphocyte clones unrelated to JT9. In contrast, anti-TNKTAR blocked, in an identical fashion, cytotoxicity of JT9 and two additional clones, JT10 and JT11, against a series of 8 sensitive targets. JT9, JT10 and JT11 human cloned NK cell lines have been derived from peripheral blood of one individual donor drawn on month 0 (JT9), 12 (JT10) and 18 (JT11). Most importantly, these three clones initially selected for their capacity to kill K562 cells have been found to express the same 90-kDa clonotypic antigen receptor structure (termed NKTa) and display identical specificity when tested against a panel of randomly selected target cell lines. We have previously demonstrated that a unique subset of NK active mature T lymphocytes interact with target cells via 90-kDa clonotypic determinants in a major histocompatibility complex-independent fashion. Taken together, the present data strongly supports the view that a surface antigen of 140 kDa, linked to cell activation, serves as a specific recognition structure at the target cell level for these NK-active T lymphocytes.

Antibodies↗
PubMed1984

Natural killer-like function of activated T lymphocytes: differential blocking effects of monoclonal antibodies specific for a 90-kDa clonotypic structure.

A monoclonal antibody termed anti-NKTb has been generated following immunization of mice with cloned human cells (JT9) displaying natural killer (NK)-like activity. This antibody has the capacity to block cytotoxicity of the immunizing clone against several targets. In the present study, anti-NKTb was compared with a monoclonal antibody termed anti-NKTa that had previously been generated against JT9 cells and that had also been shown to block the NK-like function of these cells. The expression of a NKTb determinant, like that of NKTa, was found to be restricted to two NK active clones derived from the same individual, JT9 and JT10, both of which have the same mature T-cell phenotype (T3+, T8+, T11+). Comodulation, immunoprecipitation, and competitive binding experiments showed that both antibodies are directed to the same 90-kDa heterodimer associated with the T3 structure on the cell surface. However, cytotoxicity blocking studies suggested that NKTa and NKTb may represent functionally distinct epitopes of this 90-kDa molecule. Anti-NKTa uniformly blocked the cytotoxicity of both JT9 and JT10 cells when tested against 11 randomly selected target cell lines. In contrast, anti-NKTb totally blocked the cytotoxicity of these cloned cells against some targets (i.e., HPB-ALL, Nalm-1) but had very little effect when cytotoxicity was measured against other target cells (i.e., K562, U937, KG-1). This selective blocking effect, therefore, supports the notion that the heterodimer defined by the NKT antibodies is involved in the process of target cell recognition rather than in the cytolytic pathway of the cloned effector cells. Moreover, the unique functional effects of anti-NKTb suggest that additional levels of complexity exist in the specific recognition mechanisms of these clonal populations of NK active mature T lymphocytes.

Antibodies, Monoclonal↗
PubMed1984

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

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

Adult↗
PubMed1983

Identification of a clonally restricted 90 kD heterodimer on two human cloned natural killer cell lines. Its role in cytotoxic effector function.

The present studies were carried out to identify surface molecules involved in the cytotoxic effector function of a human natural killer (NK) clone termed JT9. This clone represents a mature T lymphocyte (T3+T8+T11+) mediating NK-like activity. Using JT9 for immunization, one monoclonal antibody termed anti-NKTa was selected that blocked the cytotoxicity of the clone towards K562 cells. Reactivity of anti-NKTa antibody was assessed using a large panel of lymphoid and nonlymphoid cells including a variety of cloned cell lines with either cytotoxic T lymphocyte (CTL) or NK-like activity. Among all cells tested, only two individual clones, JT9 and JT10, were found to express NKTa antigen. JT10 was derived independently from the same individual as JT9 and also represents a mature T cell (T3+T8+T11+) mediating NK-like activity. Like the Ti structure on CTL clones, the molecule defined by anti-NKTa was shown to be membrane associated with T3 in co-modulation experiments. Moreover, anti-NKTa precipitated a 90 kD heterodimeric structure in sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of 125I surface-labeled JT9 cells. The blocking capacity of anti-NKTa was evaluated in cytotoxicity assays using a panel of target cells. The influence of anti-T3 was tested in parallel and it was found that both anti-NKTa and anti-T3 blocked the cytotoxicity of the cloned cells against all targets. Given the potential role of 90 kD molecules as antigen-receptor structures, the specificity of the two NKTa+ NK clones was compared and found superimposable when assessed using 15 in vitro established cell lines. However, in contrast to conventional CTL clones, the expression of cytotoxicity by JT9 and JT10 was not dependent upon recognition of class I or class II major histocompatibility complex gene products on the target cells. In addition, the cytotoxicity of these T8+ NK active clones could not be blocked by anti-T8 antibodies. Taken together, the present data suggest that the specificity of one population of human NK active lymphocytes is determined by clonotypic structures. The NKTa determinant identified here appears to belong to the same family of molecules as Ti structures, previously identified on antigen-specific T lymphocytes.

Antibodies, Monoclonal↗
PubMed1983

Phenotypic and functional heterogeneity of human cloned natural killer cell lines.

Extensive efforts have recently been made to characterize cells capable of mediating natural killing activity (see ref. 1 for review) and increasing evidence has arisen that these cells were heterogeneous. By using the methods we have recently developed for cloning natural killer (NK) cells derived from peripheral blood, we have analysed the heterogeneity of human NK cells. Seven cell lines showing NK activity were established and studied for 4 months. Their phenotype was determined with a series of monoclonal antibodies; anti-T1, -T3, -T4, -T8, -T11, -T12, Mo1 and each cell line appeared to have a unique phenotype. Moreover, whereas some of these lines could only kill K562 cells, the standard assay of NK activity, others displayed a broad but distinct spectrum of reactivity against a variety of human tumour and viral transformed cell lines. Taken together, these results demonstrate the phenotypic and functional heterogeneity of NK effector cells which has recently been suggested in both human and murine systems.

Cell Line↗
PubMed1983

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

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

Antibodies, Monoclonal↗
PubMed1983

Expression of MY7 antigen on myeloid precursor cells.

A murine monoclonal antibody (anti-MY7) has been developed that detects an antigen expressed by 6% of normal human bone marrow cells, including approximately 40% of myeloid colony-forming cells (CFU-C). The number of bone marrow cells and CFU-C expressing MY7 is significantly increased in regenerating bone marrow, but less than 5% of peripheral blood CFU-C express the MY7 antigen. Erythroid precursors are MY7 negative from peripheral blood and bone marrow. Thymidine suicide studies indicate that CFU-C in S-phase tend to be MY7 positive while CFU-C not in S-phase are MY7 negative. MY7 expression thus appears to identify a fraction of CFU-C that is actively proliferating.

Antibodies, Monoclonal↗
PubMed1983

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

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

Antibodies, Monoclonal↗
PubMed1983

Elimination of leukemic cells from human bone marrow using monoclonal antibody and complement.

Human leukemic cells which bear the common acute lymphoblastic leukemia antigen can be lysed with a murine monoclonal antibody (J-5) in the presence of rabbit complement. Conditions have been defined for eliminating 51Cr-labeled common acute lymphoblastic leukemia antigen-positive NALM-1 cells or cryopreserved leukemic lymphoblasts from a 100-fold excess of human bone marrow. Optimal lysis is obtained with treatment for a total of 90 min. Three treatments for 30 min are more effective than two treatments for 45 min or one treatment for 90 min. Separation of marrow on a Ficoll:diatrizoate gradient does not permit more effective elimination of leukemic cells. Tumor cell lysis is inhibited by high concentrations of common acute lymphoblastic leukemia antigen-positive cells (2 X 10(7)/ml) and by high concentrations of bone marrow (10(8)/ml). Under optimal conditions, greater than 99% of 51Cr-labeled leukemic lymphoblasts can be eliminated from a 100-fold excess of human marrow. Selective removal of leukemic cells from human bone marrow in vitro should facilitate trials of autologous marrow transplantation.

Antibodies, Monoclonal↗
PubMed1983

Selective expression of the common acute lymphoblastic leukemia (gp 100) antigen on immature lymphoid cells and their malignant counterparts.

The selectivity of monoclonal antibody J-5 (anti-gp 100, common ALL antigen) for normal and leukemic hemopoietic cells has been investigated. J-5 gave concordant reactions with rabbit anti-cALL, coredistributed on the cell surface, and precipitated a similar if not identical glycoprotein from leukemic and normal tissue. Normal, immature lymphoid cells reactive with J-5 were detected in bone marrow and in fetal thymus. In marrow they were largely coincident with the TdT+ population. J-5 defines a major subgroup of ALL (common ALL) with a favorable prognosis. Of 853 non-ALL acute leukemias investigated, 80 were J-5 positive. These included 14 cases diagnosed as AML, 51 TdT+ blast crises of CGL, and 15 cases diagnosed as "AUL." Of the 14 J-5+ AML, 13 were subsequently rediagnosed either as cALL (10 cases) or mixed lymphoid-myeloid leukemias (3 cases). One-hundred forty-three cases of mature lymphoid cell leukemia (91 B, 52 T) were investigated with J-5; 3 cases only, of disseminated B lymphoma, were positive, albeit weakly. A higher proportion of follicular lymphomas are, however, J-5 positive when studied in sections of biopsy material. A similar pattern of selective reactivity was observed in a series of leukemia/lymphoma cell lines. These studies emphasize the diagnostic value of monoclonal anti-cALL reagents.

Animals↗
PubMed1983

Differentiation patterns in the blastic phase of chronic myeloid leukemia.

The surface antigen phenotype of 30 patients with the blast phase of chronic myeloid leukemia (CML) was determined using a panel of monoclonal antibodies recognizing differentiation antigens of normal myeloid, erythroid, megakaryocyte, and lymphoid cells. Ten patients' cells expressed a phenotype corresponding to an immature myeloid cell and were felt to have "myeloid" blast crisis. None of these myeloid leukemias were TdT+ or responded to vincristine (V) and prednisone (P). Eleven patients expressed a phenotype similar to acute lymphoblastic leukemia cells and probably reflect maturation to an early B lymphocyte. All of these "lymphoid" leukemias were TdT+, and 67% of evaluable patients had a complete response to V and P. One leukemia had the phenotype of an erythroleukemia, one patient's cells expressed the phenotype of megakaryoblastic leukemia, and one leukemia had populations of both myeloid and lymphoid blasts. Six leukemias did not express surface markers characteristic of any lineage and were termed "undifferentiated." This group was heterogeneous with respect to TdT expression, but no patient had a complete response to V and P. Determination of surface antigen phenotype in CML blast crisis thus provides clinically useful information for the structuring of treatment protocols.

Adolescent↗