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Polymorphism of age‐related changes in interleukin (IL) production: differential changes of T helper subpopulations, synthesizing IL 2, IL3 and IL4

Inbred mice were examined for strain differences in age‐associated changes in the capacity to synthesize interleukin (IL), i.e. IL2, IL3 and IL4 after stimulation with phorbol myristate acetate (PMA) and calcium ionophore (A23187). Production of IL2remains constant in A/J, DBA/1 and DBA/2 mice and decreases with age in one of the strains examined (C57BL/6J). Strain differences in age‐associated changeof synthesis did not show the relation between youthful synthetic capacity and magnitude of later decrease (“economic correction”) which is observed in several other systems. This difference between different types of polymorphisms is attributed to an age‐associated defect in intrinsic capacity to synthesize IL2 which may occur in onlyone of the tested strains, C57BL/6J. In contrast to IL 2 production, the quantities of IL3 and IL4 increase progressively, with advancing age, in mice of the three strains tested. T cells from old mice contain a greater frequency of cells producing IL3, than do those of young mice. In addition, synthesis of IL3 is induced at a relatively lower concentration of PMA in cells from old animals and this may be a consequence of different signal requirements of the two subsets of the T helper cells, but also a change in intrinsic properties of these cells. Since IL3 and IL4 production, but not IL2 production, increaseswith age, it is reasonable to conclude that this reflects an expansion of a T helper cellpopulation which secretes IL3 and IL4, but not IL2, presumably TH2.