The NK function elucidated with respect to effector cells, target cells and other immunological in vitro tests.

The microcytotoxicity assay and the leukocyte migration inhibition test were unable to reveal any specific reactivity in patients suffering from localized skin melanoma. The non-specific reactivity measured by the microcytotoxicity assay, the so-called NK activity was found to be associated to the cells bearing Fc receptors, irrespective of T and non-T identity. Further more the NK activity depends on the target cell used (established cell lines versus short-term cultures) and the lymphocyte/target cell ratio. The NK activity measured by microcytotoxicity assay and the leucocyte migration inhibition test were compared by simultaneous implementation of the two test systems. No correlation between significant leucocyte migration inhibition and NK activity was found. In a tumor neutralization test workout in a nude mouse model, it was found that patient lymphocytes decreased the number of tumor takes and increase the latency period. However, the specificity of these reactions were uncertain.