ART TK Experimental chapter 23 Systems XPERIMENTAL SYSTEMS OF VARIOUS TYPES ARE ART TK used to unravel the complex cellular interactions of the immune response In vivo systems, which involve the whole animal, provide the most natural experi mental conditions. However, in vivo systems have a myriad of unknown and uncontrollable cellular interactions that add ambiguity to the interpretation of data. At the other extreme are in vitro systems, in which defined populations of lymphocytes are studied under controlled and conse- quently repeatable conditions; in vitro systems can be sim- Addition of Expression Profile of Diffuse Large B-cell Lymphoma plified to the extent that individual cellular interactions can be studied effectively. Yet they have their own limitations, the Experimental Animal Model most notable of which is their artificiality. For example, pro- iding antigen to purified B cells in vitro does not stimulate a Cell-Culture Systems maximal antibody production unless T cells are present. a Protein Biochemistry Therefore a study of antibody production in an artificial in vitro system that lacks T cells could lead to the incorrect con- a Recombinant DNA Technology clusion that B cells do not synthesize high levels of antibod- Analysis of DNA Regulatory Sequene ies. One must ask whether a cellular response observed in vitro reflects reality or is a product of the unique conditions Gene Transfer into Mammalian Cells of the in vitro system itself. a Microarrays-An Approach for Analyzing Patterns This chapter describes some of the experimental systen of Gene Expression outinely used to study the immune system. It also covers some recombinant DNA techniques that have revolution- ized the study of the immune system in the past decade orso Other chapters also cover experimental systems and tech ues in detail. Table 23-1 lists them and directs the reader to the appropriate location for a description are genetically well characterized, and have a rapid breeding cycle. The immune system of the mouse has been character ized more extensively than that of any other species. The Experimental Animal Models value of basic research in the mouse system is highlighted the enormous impact this research has had on clinical inter The study of the immune system in vertebrates requires suit- vention in human disease able els. The choice of an animal depends on suitability for attaining a particular research goal. If large Inbred Strains Can Reduce Experimental amounts of antiserum are sought, a rabbit, goat, sheep, or Variation horse might be an appropriate experimental animal. If the goal is development of a protective vaccine, the animal cho- To control experimental variation caused by differences in sen must be susceptible to the infectious agent so that the the genetic backgrounds of experimental animals, immu efficacy of the vaccine can be assessed Mice or rabbits can be nologists often work with inbred strains-that is, genetically used for vaccine development if they are susceptible to the identical animals produced by inbreeding. The rapid breed pathogen. But if growth of the infectious agent is limited to ing cycle of mice makes them particularly well suited for the humans and primates, vaccine development may require the production of inbred strains, which are developed by re use of monkeys, chimpanzees, or baboons peated inbreeding between brother and sister littermates. In For most basic research in immunology, mice have been this way the heterozygosity of alleles that is normally found he experimental animal of choice. They are easy to handle, in randomly outbred mice is replaced by homozygosity at all■ Experimental Animal Models ■ Cell-Culture Systems ■ Protein Biochemistry ■ Recombinant DNA Technology ■ Analysis of DNA Regulatory Sequences ■ Gene Transfer into Mammalian Cells ■ Microarrays—An Approach for Analyzing Patterns of Gene Expression Addition of Expression Profile of Diffuse Large B-cell Lymphoma. Experimental Systems       used to unravel the complex cellular interactions of the immune response. In vivo systems, which involve the whole animal, provide the most natural experi￾mental conditions. However, in vivo systems have a myriad of unknown and uncontrollable cellular interactions that add ambiguity to the interpretation of data. At the other extreme are in vitro systems, in which defined populations of lymphocytes are studied under controlled and conse￾quently repeatable conditions; in vitro systems can be sim￾plified to the extent that individual cellular interactions can be studied effectively. Yet they have their own limitations, the most notable of which is their artificiality. For example, pro￾viding antigen to purified B cells in vitro does not stimulate maximal antibody production unless T cells are present. Therefore a study of antibody production in an artificial in vitro system that lacks T cells could lead to the incorrect con￾clusion that B cells do not synthesize high levels of antibod￾ies. One must ask whether a cellular response observed in vitro reflects reality or is a product of the unique conditions of the in vitro system itself. This chapter describes some of the experimental systems routinely used to study the immune system. It also covers some recombinant DNA techniques that have revolution￾ized the study of the immune system in the past decade or so. Other chapters also cover experimental systems and tech￾niques in detail. Table 23-1 lists them and directs the reader to the appropriate location for a description. Experimental Animal Models The study of the immune system in vertebrates requires suit￾able animal models. The choice of an animal depends on its suitability for attaining a particular research goal. If large amounts of antiserum are sought, a rabbit, goat, sheep, or horse might be an appropriate experimental animal. If the goal is development of a protective vaccine, the animal cho￾sen must be susceptible to the infectious agent so that the efficacy of the vaccine can be assessed. Mice or rabbits can be used for vaccine development if they are susceptible to the pathogen. But if growth of the infectious agent is limited to humans and primates, vaccine development may require the use of monkeys, chimpanzees, or baboons. For most basic research in immunology, mice have been the experimental animal of choice. They are easy to handle, are genetically well characterized, and have a rapid breeding cycle. The immune system of the mouse has been character￾ized more extensively than that of any other species. The value of basic research in the mouse system is highlighted by the enormous impact this research has had on clinical inter￾vention in human disease. Inbred Strains Can Reduce Experimental Variation To control experimental variation caused by differences in the genetic backgrounds of experimental animals, immu￾nologists often work with inbred strains—that is, genetically identical animals produced by inbreeding. The rapid breed￾ing cycle of mice makes them particularly well suited for the production of inbred strains, which are developed by re￾peated inbreeding between brother and sister littermates. In this way the heterozygosity of alleles that is normally found in randomly outbred mice is replaced by homozygosity at all chapter 23 ART TK E ART TK