Immune function tiered testing

Host-resistance assays can be used to assess the overall immunocompetence of the humoral or cell-mediated immune systems of the test animal (host) to fend off infection with pathogenic microbes, or to resist tumorigenesis and metastasis. These assays are performed entirely in vivo and are dependent on all of the various components of the immune system to be functioning properly. Thus, these assays may be considered to be more biologically relevant than in vitro tests that only assess the function of cells from one source and of one type. Since these assays require that the animal be inoculated with a pathogen or exogenous tumor cell, they cannot be performed as part of a general preclinical toxicity assessment, and are thus classified as Type 2 tests in the revised Redbook. These assays are also included as Tier II tests by the NTP. 

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