Interleukin-12 release by mitogen-stimulated mononuclear cells in the elderly.

Defects involving cellular expression of activation molecules, cell mediated immune response and natural killer (NK) activity are commonly observed in the elderly. Herein, data are reported on the evaluation of IL-12 production by old subjects. IL-12 is, actually, considered the key molecule for the induction of a T helper 1 (Th1) -type and NK response. IL-12 production from old subjects peripheral blood mononuclear cells (PBMNC) was evaluated using T-independent (bacterial lipopolysaccharide, LPS) or -dependent (phytoemagglutinin, PHA; immobilized anti-CD3 monoclonal antibodies, anti-CD3) mitogens. The IL-12 production after LPS stimulation was not reduced in cultures from old subjects when compared to that from young ones. On the contrary, IL-12 production by PHA or anti-CD3 stimulated PBMNC from old subjects was decreased. Furthermore, we have demonstrated a reduced CD40 and CD40 ligand (CD40L) expression on PBMNC from old subjects. This finding fits very well with the reduced cytokine production observed in the T-dependent stimulation systems, being the CD40-CD40L interaction mandatory for an efficient IL-12 production. All together, these results seem to suggest that defects in cell expression of activation molecules can affect the IL-12 secretion and in consequence other Th1-type cytokines.