Leu-1 Antibodies Research Articles

An antigen common to chronic lymphocytic and hairy cell leukemia cells not shared by normal lymphocytes or by other leukemic cells

Rabbit xenoantisera and mouse monoclonal antibodies prepared against human chronic lymphocytic leukemia (CLL) B cells were found to react against a single polypeptide chain with a mol wt of 69 kd found on leukemic cells of all CLL (N = 40) and B type hairy cell leukemia (HCL) patients (N = 9) examined. This common CLL-associated antigen (cCLLa) was not detectable on circulating T or B lymphocytes, thymocytes, lymph node and splenic lymphocytes, or bone marrow leukocytes from normal persons. In addition, the cCLLa was not detectable on cultured T or B lymphoblastoid cell lines or on malignant cells from other forms of lymphocytic or myelocytic leukemia. Non-Hodgkin's lymphoma cells also failed to express the antigen. Autologous cultured lymphoblastoid cell lines were established from residual normal B cells from a CLL patient whose cells were used to generate one of the antisera. Absorption of the antibody with these cultured polyclonal B cells did not affect the anti-CLL activity, which suggests that the cCLLa is not HLA related. Unlike the T cell differentiation complex gp65–71, the cCLLa was not expressed on fetal or cord blood lymphocytes or on mitogen-stimulated normal lymphocytes and was distinct from the antigen recognized by the LEU-1 antibody in spite of their similar mol wt. The cCLLa was also determined to be unrelated to the human T cell leukemia lymphoma virus (HTLV-1). One of the monoclonal antibodies generated against the cCLLa was a complement binding IgG which exhibited highly selective cytotoxic activity against 100% of cells bearing the cCLLa. Such an antibody might prove clinically useful in early diagnosis and treatment of CLL and HCL.

An Antigen Common to Chronic Lymphocytic and Hairy Cell Leukemia Cells Not Shared by Normal Lymphocytes or by Other Leukemic Cells

Rabbit xenoantisera and mouse monoclonal antibodies prepared against human chronic lymphocytic leukemia (CLL) B cells were found to react against a single polypeptide chain with a mol wt of 69 kd found on leukemic cells of all CLL (N = 40) and B type hairy cell leukemia (HCL) patients (N = 9) examined. This common CLL-associated antigen (cCLLa) was not detectable on circulating T or B lymphocytes, thymocytes, lymph node and splenic lymphocytes, or bone marrow leukocytes from normal persons. In addition, the cCLLa was not detectable on cultured T or B lymphoblastoid cell lines or on malignant cells from other forms of lymphocytic or myelocytic leukemia. Non-Hodgkin's lymphoma cells also failed to express the antigen. Autologous cultured lymphoblastoid cell lines were established from residual normal B cells from a CLL patient whose cells were used to generate one of the antisera. Absorption of the antibody with these cultured polyclonal B cells did not affect the anti-CLL activity, which suggests that the cCLLa is not HLA related. Unlike the T cell differentiation complex gp65-71, the cCLLa was not expressed on fetal or cord blood lymphocytes or on mitogen-stimulated normal lymphocytes and was distinct from the antigen recognized by the LEU-1 antibody in spite of their similar mol wt. The cCLLa was also determined to be unrelated to the human T cell leukemia lymphoma virus (HTLV-1). One of the monoclonal antibodies generated against the cCLLa was a complement binding IgG which exhibited highly selective cytotoxic activity against 100% of cells bearing the cCLLa. Such an antibody might prove clinically useful in early diagnosis and treatment of CLL and HCL.

Identification of lymphocyte subsets and natural killer cells in head and neck cancers. An immunohistological study using monoclonal antibodies.

We investigated host-immune defenses against head and neck cancer cells by using various monoclonal antibodies with an immunoperoxidase technique to define lymphocyte subsets and natural killer (NK) cells. By so doing, we were able to identify lymphocyte subsets and NK cells in various head and neck cancers. We found that the majority of these cells infiltrate in or around nests of cancer cells and are stained with Leu-1 antibody. They include both Leu-2a and Leu-3a positive cells, which show equally intense levels of infiltration. Leu-7 positive cells were only scattered in the peripheral portion of the cancer nests in some cases. We also found a tendency for T-cells to infiltrate more intensely in poorly differentiated squamous cell carcinomas (SCC) than in moderately or well-differentiated SCC. Similarly, T-cells were more prevalent in maxillary carcinomas than in laryngeal carcinomas. These findings suggest the presence of a host-immune defense mechanism against cancer cells in patients with head and neck cancers.

Two distinct cytotoxic T lymphocyte subpopulations in patients with Vogt-Koyanagi-Harada disease that recognize human melanoma cells.

The functional properties of cytotoxic lymphocytes from patients with Vogt-Koyanagi-Harada disease ( VKH ) specific for human melanoma cells (P-36 melanoma cell line established from a patient with malignant melanoma) were investigated by using monoclonal antibodies specific for human T cell subsets. Peripheral blood lymphocytes (PBL) from patients with VKH showed significant cytotoxic activity against the P-36 (SK-MEL-28) human melanoma cell line, but not against a human cervical carcinoma of the uterus cell line (HeLa-S3 cell line) or against a mouse melanoma cell line (B-16 cell line) originating from a C57BL/6 strain mouse or against the EL-4 mouse lymphoma cell line from a C57BL/6 mouse. The cytotoxic activity of the patients' PBL against the P-36 melanoma cell line was markedly reduced by pretreatment of the PBL with monoclonal anti-human Leu-1 antibody plus rabbit complement, but it was reduced to much less extent by pretreatment with either monoclonal anti-human Leu-2a or Leu-3a antibody plus rabbit complement. The specific cytotoxic activity of the patients' PBL against the P-36 human melanoma cell line is, therefore, mediated by T cells bearing Leu-1+ Leu-2a+ or Leu-1+ Leu-3a+ antigens. Furthermore, the cytotoxic activity was shown to be blocked not only by anti-Leu-2a antibody specific to human cytotoxic/suppressor T cells but also unexpectedly by anti-Leu-3a antibody which has previously been considered to be specific to human inducer/helper T cells. The results of this study suggest that at least two distinct subpopulations of cytotoxic T cells specific for P-36 human melanoma cells are present in the peripheral blood of VKH patients. These cytotoxic T cells have different surface antigens, Leu-2a and Leu-3a.

Lymphokine-activated killer cell phenomenon. II. Precursor phenotype is serologically distinct from peripheral T lymphocytes, memory cytotoxic thymus-derived lymphocytes, and natural killer cells.

Culture of human peripheral blood lymphocytes (PBL) in partially purified and lectin-free interleukin 2 results in the generation of cytotoxic effector cells which have the unique property of lysing natural killer (NK)-resistant fresh human tumor cells. We have termed these effector cells "lymphokine- activated killer" cells (LAK). LAK are generated from both normal and cancer patients' PBL and are able to lyse both autologous and allogeneic tumor cells from all histologic tumor types tested. Our previous studies suggested that the LAK phenomenon was distinct from either the cytotoxic thymus-derived lymphocyte (CTL) or NK systems based on a variety of criteria. This study reports that the cell type involved is also distinct, as determined by phenotypic characteristics. The LAK effector cell phenotype was analyzed in parallel with alloimmune CTL, and LAK were found to be similarly susceptible to the monoclonal anti-T cell antibodies OKT-3 or OKT-8 plus complement. In contrast the LAK precursor was not susceptible to the OKT-3 or Leu-1 antibodies plus complement, while the ability to generate alloimmune CTL was totally obliterated when tested using the same PBL responder population; in fact, generation of LAK was found to be augmented five- to sixfold, clearly suggesting that LAK precursor cells are not T lymphocytes as defined by these antibodies. LAK precursors were found to be abundant in NK cell-enriched Percoll gradient fractions, which had been depleted of the 29 degrees C E- rosetting "high affinity" T cells. However, LAK precursors were found to be distinct from the majority of NK cells since lysis of fresh PBL with the monoclonal antibodies OKM-1, Leu-7, or OKT-11 significantly depleted or totally eliminated NK activity, while subsequent activation of the remaining cells generated high levels of LAK and in some cases augmented levels of LAK. LAK precursors were found to be distributed in the thymus, bone marrow, spleen, lymph node, and thoracic duct in addition to the PBL. Therefore, while the cell(s) responsible for activation and expression of LAK activity have some common features with the classic T cell-mediated CTL and NK cell systems, the LAK precursor cells are clearly distinct as determined by phenotype analysis using monoclonal antibodies and complement, and at present must be classified as a "null" cell.

Identification of T-cell Subpopulations in Granuloma Annulare

Granuloma annulare is a lymphohistiocytic process of unknown cause characterized by necrobiotic dermal papules. Acetone-fixed frozen sections of eight granuloma annulare lesions were studied for the presence of T-cell subsets, using monoclonal antibodies to T-cell surface antigens. The palisading and perivascular lymphocytic infiltrate shows that most of the mononuclear cells are reactive with LEU-1 antibody, which characterizes peripheral T cells and activated T cells. Numerous cells were reactive with LEU-3a antibody, which identifies the helper-inducer T-cell subset. Some cells were positive with LEU-2a antibody, which detects suppressor-cytotoxic cell populations. Masses of histiocytes were identified infiltrating between the collagen fibers and surrounding the central necrobiosis area; the histiocytes showed a very strong diffuse acid phosphatase and nonspecific esterase activity. These findings suggest that a cell-mediated immune response may be the dominant pathogenic event in granuloma annulare.

Immunologic classification of lymphocytic leukemias based on monoclonal antibody-defined cell surface antigens

A panel of monoclonal antibodies reactive with normal lymphocyte subsets was used to classify cases of lymphocytic leukemia on the basis of cell surface antigen expression. The antibodies employed were commercially available and included a common framework HLA-DR antibody, two pan-T antibodies (Leu-1 and OKT-3), and antibodies defining cytotoxic/suppressor (Leu-2 and OKT-8) and helper/inducer (Leu-3 and OKT-4) subpopulations of normal T lymphocytes. Cases of ALL could be subgrouped into non-T non-B, pre-T and T-ALL on the basis of reactivity with HLA-DR, Leu-1, and OKT-3 antibodies. Leukemic cells from patients with T-cell CLL could be divided into Leu-2/OKT-8 reactive and Leu-3/OKT-4 reactive subpopulations, as well as a subgroup in which the majority of cells were unreactive with either of these antibodies. With the exception of one individual, all Sézary cell leukemias expressed a phenotypic pattern similar to that of the Leu-3 subgroup of T-CLL. Malignancies of B-cell lineage (B-CLL, prolymphocytic leukemia, and lymphosarcoma) that were examined were reactive with both the HLA-DR and Leu-1 antibodies. On the contrary, normal B lymphocytes and lymphoid cell lines of B-cell origin did not express surface antigens recognized by the Leu-1 antibody.

Immunologic classification of lymphocytic leukemias based on monoclonal antibody-defined cell surface antigens

A panel of monoclonal antibodies reactive with normal lymphocyte subsets was used to classify cases of lymphocytic leukemia on the basis of cell surface antigen expression. The antibodies employed were commercially available and included a common framework HLA-DR antibody, two pan-T antibodies (Leu-1 and OKT-3), and antibodies defining cytotoxic/suppressor (Leu-2 and OKT-8) and helper/inducer (Leu-3 and OKT-4) subpopulations of normal T lymphocytes. Cases of ALL could be subgrouped into non-T non-B, pre-T and T-ALL on the basis of reactivity with HLA-DR, Leu-1, and OKT-3 antibodies. Leukemic cells from patients with T-cell CLL could be divided into Leu-2/OKT-8 reactive and Leu- 3/OKT-4 reactive subpopulations, as well as a subgroup in which the majority of cells were unreactive with either of these antibodies. With the exception of one individual, all Sezary cell leukemias expressed a phenotypic pattern similar to that of the Leu-3 subgroup of T-CLL. Malignancies of B-cell lineage (B-CLL, prolymphocytic leukemia, and lymphosarcoma) that were examined were reactive with both the HLA-DR and Leu-1 antibodies. On the contrary, normal B lymphocytes and lymphoid cell lines of B-cell origin did not express surface antigens recognized by the Leu-1 antibody.

The role of cytotoxic T lymphocytes in the pathogenesis of Vogt-Koyanagi-Harada disease.

Peripheral blood lymphocytes (PBL) were isolated from blood of 6 patients with Vogt-Koyanagi-Harada disease (VKH), and their cytotoxic activity was assayed using 51Cr release from the labelled cells; the cytotoxicity was expressed as percentage release in reference to the complete release using saponin. The PBLs from the patients showed a significant cytotoxic activity against P-36 human melanoma cells, and the specificity of the reaction was confirmed by the cold target inhibition test and also by the use of HeLa-S3 human cervical carcinoma cells and B-16 mouse melanoma cells, since no significant cytotoxicity was seen against these cells. The cytotoxic activity was greatly reduced by pretreatment of the PBLs with monoclonal antihuman Leu-1 antibody plus the rabbit complement. It was, therefore, thought that the cytotoxic activity against the melanoma cells is mainly due to T cells. In addition, the cytotoxic activity was specifically blocked by monoclonal antihuman Leu-2a antibody, the specificity of which is distributed on cytotoxic/suppressor T cell subset of normal human peripheral lymphocytes and normal human thymocytes. A possibility was discussed as regards the involvement of the cytotoxic T lymphocytes in the pathogenesis of VKH.