Introduction: S.H.E. Kaufmann and D. Kabelitz, The Immune Response to Infectious Agents. General Methods: A. Scheffold and A. Radbruch, Phenotyping and Separation of Leukocyte Populations. D. Kabelitz and K. Pechold, Measurement of Cellular Proliferation (3H-TdR, MTT, Absolute Cell Numbers by SCUD). Murine Models: H. Mossmann, Management of Infected and Immunocompromised Animals. C.J. Czuprynski and J.F. Brown, In Vitro Analysis. W. Born, M. Tsuji, C. Cady, M. Lahn, A. Mukasa, C. Reardon, and R. O'Brien, Establishment of Murine T Cell Lines, T Cell Clones, Hybridomas and Transfectomas. D.H. Busch and E.G. Pamer, Killer Cell Assays. R. Haworth and S. Gordon, Isolation of Professional Phagocytes and Measuring their Functions: Murine Macrophages in Vitro. M. Mielke, In Vivo Analyses. S. Ehlers and U. Seitzer, Measuring Immune Responses in Vivo. A.D. Roberts, J.T. Belisle, A.M. Cooper, and I.M. Orme, Specific Models. P. Kropf, K. Brunson, R. Etges, and I. Muller, The Leishmaniasis Model. J.B. Ulmer, J.J. Donnelly, D.L. Montgomery, and M.A. Liu, Art and Science of DNA Vaccines. K. Lovgren-Bengtsson, Preparation and Use of Adjuvants. Human System: J. Banchereau, Isolation and Propagation of Dendritic Cells. E. Marker-Hermann and R. Duchmann, Isolation of T Cells and Establishment of T Cell Lines and Clones. H. Fickenscher and B. Fleckenstein, Growth-Transformation of Human T Cells. G. Pawelec, E. Mariani, R. Offringa, C.J.M. Melief, and R. Solana, Generation and Characterization of Killer Cells. H. Yssel and F. Cottrez, Measuring Human Cytokine Responses. U. Seitzer and J. Gerdes, Measuring Immune Responses in Situ: Immunohistology and in Situ Hybridization. S.W. Krause, M. Kreutz, and R. Andreesen, Isolation, Characterization, and Cultivation of Human Monocytes and Macrophages.