Published online by Cambridge University Press: 17 March 2009
Several functions of the animal body can take place in cell or tissue cultures with almost unreduced efficiency and precision. Functions, where only one cell type is involved, often do so, but also some differentiation steps where interactions between two or more cell types are clearly needed can take place in tissue culture (Saxén et al. 1968).
Most immune responses require collaboration between two or more cell types (Claman, Chaperon & Triplett, 1966; Miller & Mitchell, 1968; Feldmann & Nossal 1972c). Some of them can be easily induced in vitro but others cannot. Even when antibody responses can be induced in vitro their intensity varies a great deal. With some antigens and under some circumstances a response in vitro can be nearly as strong as one in vivo. A crude comparison can be derived from responses in vitro and in vivo to the same antigen, conjugate of hapten NIP and pneumococcal polysaccharide type III (NIP-SIll, Nakamura, Ray & Mäkelä, 1973).