Isolation and characterization of an immortal neoplastic cell line (KS Y-1) from AIDS-associated Kaposi's sarcoma.

BACKGROUND: Acquired immunodeficiency syndrome (AIDS) is associated with the occurrence of tumors such as Kaposi's sarcoma (KS) and B-cell lymphoma. However, no evidence exists yet that human immunodeficiency virus type 1, the causative agent of AIDS, is directly responsible for cell transformation. It is also not clear whether KS lesions, which are of complex cellularity, contain tumor cells derived from a true monoclonal malignancy (originating from a single malignant cell) or whether the lesions are just polyclonally hyperplastic in nature (containing increased numbers of normal cells). In fact, the presence of malignant KS cells has never been unequivocally shown in AIDS-associated KS, and previously isolated KS cell cultures were not immortal or malignant. PURPOSE: Our purpose was to (a) utilize technology that could facilitate isolation and enrichment of tumor cells from AIDS-associated KS lesions, (b) establish and characterize an immortalized KS cell line, and (c) test the malignant potential of such a cell line in animal models. METHODS: Mononuclear cells were isolated from 2.5 L of pleural effusion from an AIDS-associated KS patient. T-lymphocytes, B-lymphocytes, monocytes/macrophages, and fibroblasts were removed by a cytotoxicity method, using monoclonal antibodies specific for cell surface markers and baby rabbit complement. KS cells were cultured in the absence of exogenous growth factors in an effort to select for transformed cells capable of self-sustained growth. The karyotype abnormalities were detected by G-banded marker studies, and phenotypic markers were determined by indirect immunofluorescence and immunocytochemical methods. Beige nude XID and severe combined immunodeficient mice were used to evaluate the tumorigenic, angiogenic, and metastatic potentials of cells. RESULTS: An immortalized cell line, named KS Y-1, was isolated. Its phenotype is similar to that of endothelial cells with positive CD34 and CD31 markers. Tetraploid chromosomal abnormalities were found in primary fresh KS tissue and in vitro passages of KS Y-1 cells. These cells promoted tumorigenesis, angiogenesis, and metastasis in immunodeficient mice. Tumors produced at the site of injection as well as metastases in the lung, spleen, pancreas, gastrointestinal tract, and skin showed a human tetraploid karyotype. KS Y-1 cells show high plating efficiency. CONCLUSION: The KS Y-1 cell line could be the first evidence of AIDS-associated KS cells that may develop clones with an indisputable malignant cell phenotype. IMPLICATIONS: KS Y-1 cells in the in vivo mouse model can be used to study the effects of therapeutic compounds in advanced KS.

Tumorigenesis and metastasis of neoplastic Kaposi's sarcoma cell line in immunodeficient mice blocked by a human pregnancy hormone.

Kaposi's sarcoma (KS) occurs more often in men than in women and HIV-1-associated KS has a high occurrence in homosexual men (over 30%). Most cultures of KS tumours yield cells with properties of hyperplastic (not malignant) endothelial cells under the control of several cytokines. The role of HIV-1 may be in promoting high levels of some cytokines and providing stimulation to angiogenesis by the HIV-1 Tat protein, which synergizes with basic fibroblast growth factor in promoting these effects. Here we describe an immortalized AIDS-KS cell line (KS Y-1) and show that these cells produce malignant metastatic tumours in nude mice and are killed in vitro and in vivo (apparently by apoptosis) by a pregnancy hormone, the beta-chain of human chorionic gonadotropin. Similarly, chorionic gonadotropin kills KS SLK, cells from another neoplastic cell line (established from a non-HIV-associated KS), as well as the hyperplastic KS cells from clinical specimens grown in short-term culture, but does not kill normal endothelial cells. These results provide evidence that KS can evolve into a malignancy and have implications for the hormonal treatment of this tumour.

Abnormal in vitro proliferation and differentiation of T cell colony-forming cells in patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy and healthy HTLV-I carriers.

T cell colonies were generated from the peripheral blood mononuclear cells (PBMC) of 10 patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy (TSP/HAM), two healthy HTLV-I carriers, and 17 healthy HTLV-I-seronegative subjects. PBMC were cultured in methylcellulose in the absence of added growth factors (spontaneous T cell colonies), or in the presence of phorbol myristate acetate and interleukin 2 (induced T cell colonies). PBMC T cell colony-forming cells (T-CFC) from all TSP/HAM patients and HTLV-I carriers were able to grow in the absence of added growth factors and/or mitogenic stimulation. Pooled spontaneous and induced colonies were composed of cells bearing CD3+, CD4+, CD8+, and CD1+ antigens. Colonies from normal HTLV-I-seronegative subjects displayed mature cells bearing the CD3+, CD4+, CD8+, and CD1- surface phenotype. In addition, spontaneous and induced T cell colonies expressed HTLV-I antigens in 18-38% of the cells from TSP/HAM patients and HTLV-I carriers. These results demonstrate that HTLV-I infection is associated with an abnormal proliferation and differentiation of T cell progenitors in vitro and that the T-CFC from HTLV-I-seropositive individuals are infected, suggesting that T-CFC abnormalities may play a predominant role in the pathophysiology of HTLV-I.