Experimental Systems CHAPTER 23 529 Cell lines commonly used in grown for extended periods in tissue culture, enabling im TABLE 23-3 immunologic research munologists to obtain large numbers of homogeneous cells in culture Cell line Description Until the late 1970s, immunologists did not succeed maintaining normal T cells in tissue culture for extended Mouse fibroblast cell line often used in periods. In 1978, a serendipitous finding led to the observa DNA transfection studies and to assay tion that conditioned medium containing a T-cell growth tumor necrosis factor (NF) factor was required. The essential component of the condi sP2/0 Nonsecreting mouse myeloma; often ioned medium turned out to be interleukin 2(IL-2). By cul- used as a fusion partner turing normal T lymphocytes with antigen in the presence of hybridoma secretion L-2, clones of antigen-specific T lymphocytes could be P3X63-Ag8653 Nonsecreting mouse myeloma; often sed as a fusion partner for lated. These individual clones could be propagated and stud- hybridoma secretion ied in culture and even frozen for storage. After thawing, the MPC 11 IgG2b-secreting myeloma clones continued to grow and express their original antigen- specific functions P3X63Ag8 Mouse lgG1-secreting myeloma Development of cloned lymphoid cell lines has enabled MOPC 315 Mouse IgA-secreting myeloma munologists to study a number of events that previously could not be examined. For example, research on the molec 70Z/3 Mouse pre-B-cell lymphoma; used to ular events involved in activation of naive lymphocytes by study earby events in B-cell differentiation antigen was hampered by the low frequency of naive B and BCL 1 Mouse B-cell leukemia lymphoma that T cells specific for a particular antigen; in a heterogeneous expresses membrane IgM and IgD and population of lymphocytes, the molecular changes occurring can be activated with mitogen to in one responding cell could not be detected against a back ground of 10-10 nonresponding cells. ClonedT-and B-cell CTLL-2 Mouse T-cell line whose growth is lines with known antigenic specificity have provided immu pendent on IL-2; often used to assay IL-2 production nologists with large homogeneous cell populations in which to study the events involved in antigen recognition. Similarly, Jurkat Human T-cell leukemia that secretes IL-2 the genetic changes corresponding to different maturational Do1110 Mouse T-cell hybridoma with specificity stages can be studied in cell lines that appear to be"frozenat different stages of differentiation. Cell lines have also bee Mouse monocyte-macrophage line useful in studying the soluble factors produced by lymphoid P338D1 Mouse monocyte-macrophage line that cells. Some cell lines secrete large quantities of various cyto- secretes high levels of IL-1 kines; other lines express membrane receptors for particular WEH 265.1 Mouse monocyte line tokines. These cell lines have been used by immunologists Mouse mastocytoma cells; often used as to purify various cytokines and their receptors and eventu- target to assess killing by cytotoxic ally to clone their T lymphocytes(CTLs With the advantages of lymphoid cell lin es come a num YAC-1 Mouse lymphoma cells; often used as of limitations. Variants arise spontaneously in the course of arget for NK cells cloning to limit Human myeloid-leukemia cell line the cellular heterogeneity that can develop. If variants are African green monkey kidney cells selected in subcloning, it is possible that two subclones derived transformed by SV40; often used in rom the same parent clone may represent different subpopu- DNA transfection studies lations. Moreover, any cell line derived from tumor cells or characteristic of the tumor or of the transformed state thus, researchers must be cautious when extrapolating results ob- tained with cell lines to the normal situation in vivo neverthe. (SV40), Epstein-Barr virus(EBV), or human T-cell leukemia less, transformed cell lines have made a major contribution to the study of the immune response, and many molecular events Lymphoid cell lines differ from primary lymphoid cell discovered in experiments with transformed cell lines have cultures in several important ways: They survive indefinitely been shown to take place in normal lymphocytes. in tissue culture, show various abnormal growth properties, with more or less than the normal diploid number of chro. Hybrid Lymphoid Cell Lines mosomes for a species are said to be aneuploid. The big In somatic-cell hybridization, immunologists fuse normal B advantage of cloned lymphoid cell lines is that they can be or T lymphocytes with tumor cells, obtaining hybrid cells, or(SV40), Epstein-Barr virus (EBV), or human T-cell leukemia virus type 1(HTLV-1). Lymphoid cell lines differ from primary lymphoid cell cultures in several important ways: They survive indefinitely in tissue culture, show various abnormal growth properties, and often have an abnormal number of chromosomes. Cells with more or less than the normal diploid number of chro￾mosomes for a species are said to be aneuploid. The big advantage of cloned lymphoid cell lines is that they can be grown for extended periods in tissue culture, enabling im￾munologists to obtain large numbers of homogeneous cells in culture. Until the late 1970s, immunologists did not succeed in maintaining normal T cells in tissue culture for extended periods. In 1978, a serendipitous finding led to the observa￾tion that conditioned medium containing a T-cell growth factor was required. The essential component of the condi￾tioned medium turned out to be interleukin 2 (IL-2). By cul￾turing normal T lymphocytes with antigen in the presence of IL-2, clones of antigen-specific T lymphocytes could be iso￾lated. These individual clones could be propagated and stud￾ied in culture and even frozen for storage. After thawing, the clones continued to grow and express their original antigen￾specific functions. Development of cloned lymphoid cell lines has enabled immunologists to study a number of events that previously could not be examined. For example, research on the molec￾ular events involved in activation of naive lymphocytes by antigen was hampered by the low frequency of naive B and T cells specific for a particular antigen; in a heterogeneous population of lymphocytes, the molecular changes occurring in one responding cell could not be detected against a back￾ground of 103 –106 nonresponding cells. Cloned T- and B-cell lines with known antigenic specificity have provided immu￾nologists with large homogeneous cell populations in which to study the events involved in antigen recognition. Similarly, the genetic changes corresponding to different maturational stages can be studied in cell lines that appear to be “frozen” at different stages of differentiation. Cell lines have also been useful in studying the soluble factors produced by lymphoid cells. Some cell lines secrete large quantities of various cyto￾kines; other lines express membrane receptors for particular cytokines. These cell lines have been used by immunologists to purify various cytokines and their receptors and eventu￾ally to clone their genes. With the advantages of lymphoid cell lines come a number of limitations. Variants arise spontaneously in the course of prolonged culture, necessitating frequent subcloning to limit the cellular heterogeneity that can develop. If variants are selected in subcloning, it is possible that two subclones derived from the same parent clone may represent different subpopu￾lations. Moreover, any cell line derived from tumor cells or transformed cells may have unknown genetic contributions characteristic of the tumor or of the transformed state; thus, researchers must be cautious when extrapolating results ob￾tained with cell lines to the normal situation in vivo. Neverthe￾less, transformed cell lines have made a major contribution to the study of the immune response, and many molecular events discovered in experiments with transformed cell lines have been shown to take place in normal lymphocytes. Hybrid Lymphoid Cell Lines In somatic-cell hybridization, immunologists fuse normal B or T lymphocytes with tumor cells, obtaining hybrid cells, or Experimental Systems CHAPTER 23 529 TABLE 23-3 Cell lines commonly used in immunologic research Cell line Description L-929 Mouse fibroblast cell line; often used in DNA transfection studies and to assay tumor necrosis factor (TNF) SP2/0 Nonsecreting mouse myeloma; often used as a fusion partner for hybridoma secretion P3X63-Ag8.653 Nonsecreting mouse myeloma; often used as a fusion partner for hybridoma secretion MPC 11 Mouse IgG2b-secreting myeloma P3X63-Ag8 Mouse IgG1-secreting myeloma MOPC 315 Mouse IgA-secreting myeloma J558 Mouse IgA-secreting myeloma 7OZ/3 Mouse pre–B-cell lymphoma; used to study early events in B-cell differentiation BCL 1 Mouse B-cell leukemia lymphoma that expresses membrane IgM and IgD and can be activated with mitogen to secrete IgM CTLL-2 Mouse T-cell line whose growth is dependent on IL-2; often used to assay IL-2 production Jurkat Human T-cell leukemia that secretes IL-2 DO11.10 Mouse T-cell hybridoma with specificity for ovalbumin PU 5-1.8 Mouse monocyte-macrophage line P338 D1 Mouse monocyte-macrophage line that secretes high levels of IL-1 WEHI 265.1 Mouse monocyte line P815 Mouse mastocytoma cells; often used as target to assess killing by cytotoxic T lymphocytes (CTLs) YAC-1 Mouse lymphoma cells; often used as target for NK cells HL-60 Human myeloid-leukemia cell line COS-1 African green monkey kidney cells transformed by SV40; often used in DNA transfection studies