The role of natural killer cells in human tonsillar tissue focussing on the change of tonsillar tissue with aging.

The natural killer (NK) activity of tonsillar lymphocytes is low and NK-cells are small in number. In tonsillar tissue, NK-cells were present in the germinal center, which is where B-cells are located. This suggests that B-cells are related to NK-cells. Judging from the rates of augmentation of NK-activity of INF-alpha, INF-beta, and from the fact that there is no difference in the rate of NK-activity augmentation between tonsillar and peripheral blood lymphocytes with IFN added, it is highly unlikely that there is much difference between the ratios of pre-NK cells and NK-cells. The fact that the NK-activity augmentation in the tonsil rose to approximately double that of peripheral blood on the addition of IL-2 suggests that the percentage of immature NK-cells is high in the tonsil. This supposition is in agreement with the morphological findings. In the infected and child tonsil, it is probable that NK-cells are at an immature stage, that NK-activity is low, that B-cells are active, and that immunoglobulin production is in progress.