Anatomical environment as a determinant in viral immunity.

The immune response is not monolithic. The phenotype of immunity is modulated by the range of environments that lymphocytes experience as they passage through, or lodge for a time in, both secondary lymphoid tissue and other organ systems. Although we are constrained to think in terms of the homogeneity characteristic of the tissue culture flask, the cellular events in particular in vivo sites can vary considerably. The profiles found for accessible "windows" such as the blood, tonsil, or spleen do not necessarily reflect the totality of the host response. The theme of anatomically related divergence in the effector and memory phases of immunity is developed here, using examples from experiments with viruses.