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

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Abstract

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.

Introduction

Deterioration of immune function in old age is a common finding. This progressive decline of the immune system, defined `immunosenescence' (Pawelec et al., 1997), is one of the several physiologic changes thought to occur during mammalian ageing. Weakening of T cell activity in old patients is in vivo clearly shown by decreased delayed type hypersensitivity tests to recall antigens as well as by immunization procedures in which T-cell dependent antibody production is defective (Thoman and Weigle, 1989, Song et al., 1993). These age-related changes are clearly evident in the peripheral T cell pool. Age-associated changes of Th1-like or Th2-like cytokine production (Romagnani, 1995) by CD4-positive T cells are clearly demonstrated (Hobbs et al., 1991, Pawelec, 1995). We have previously reported that production of some Th1-like cytokines by mitogen-stimulated peripheral blood mononuclear cells (PBMNC) is reduced in elderly (Candore et al., 1993, Caruso et al., 1996). The mechanisms involved in the age related Th1-like cytokine impairment are not completely understood although changes in intra- and intercellular signaling impairment might be involved.

Interleukin-12 (IL-12) is now considered the key cytokine for the induction of a Th1-type response. One of most important effect of IL-12 is the strong enhancement of interferon-γ (IFN-γ) synthesis by T and natural killer (NK) cells (Chan et al., 1992). In addition, IL-12 activates both T and NK cytotoxic activity (Gately et al., 1992), playing a major role in defense against parasitic and viral infections (Afonso et al., 1994, Orange et al., 1995). The well documented increased susceptibility of elderly individuals to various infectious and neoplastic diseases might be so related to an impairment of IL-12 production with a lack of the optimal conditions for Th1-like cytokine synthesis (Candore et al., 1993).

To evaluate IL-12 involvement in the elderly related immune dysfunction, the cytokine production by PBMNC from old and young subjects stimulated with non-T mitogens (bacterial lipopolysaccharide, LPS) and T-dependent (phytoemagglutinin, PHA; immobilized anti-CD3 monoclonal antibodies, anti-CD3) mitogens was evaluated.

Section snippets

Subjects

Fifteen old Sicilians were studied (eight women and seven men, range 66–84 years). None of the selected subjects was affected by neoplastic, infectious or autoimmune disease, not received any drug influencing immune functions at the time of the study. As a control, 12 staff laboratory healthy Sicilians (six women and six men, range 21–40 years) were studied.

Cell cultures

PBMNC from old and young subjects were isolated by centrifugation on Ficoll-Hipaque gradient (Nycomed As, Diagnostic, Oslo, Norway) and

IL-12 production by stimulated mononuclear cells

IL-12 production by either unstimulated or stimulated PBMNC cultures from old and young individuals was analyzed at 48 h (Table 1). Supernatants from the all in vitro cultures, stimulated with PHA, immobilized anti-CD3, or LPS, contained increased cytokine concentrations respect to unstimulated ones. IL-12 production by PHA stimulated mononuclear cells from old subjects was significantly reduced when compared to that from young ones. Similar results were obtained using immobilized anti-CD3

Discussion

We have recently reported that besides IL-2 and soluble form of its receptor, also the ability to produce IFN-γ was impaired in mitogen-stimulated T cells from old healthy subjects, whereas the cell capability to produce IL-4 and IL-6 was not affected (Caruso et al., 1991, Candore et al., 1992, Candore et al., 1993). Since IL-12 plays a major role in the induction of Th1-like response and particularly in the IFN-γ production (Kubin et al., 1994), in this study we have evaluated IL-12 production

Acknowledgements

This work was supported by grants from MURST, Rome (60%) to C.C. and D.L. and C.N.R., Rome to C.C.

References (38)

  • M. Utsuyama et al.

    Impairment of signal transduction in T-cells from old mice

    Mech. Ageing Develop.

    (1997)
  • R.L. Whisler et al.

    Age related decreases in IL-2 production by human T-cells are associated with impaired activation of nuclear transcriptional factors AP-1 and NF-AT

    Cell. Immunol.

    (1996)
  • L.C.C. Afonso et al.

    The adiuvant effect of interleukin-12 in a vaccine against Leishmania Major

    Science

    (1994)
  • J. Banchereau et al.

    The CD40 antigen and its ligand

    Annu. Rev. Immunol.

    (1994)
  • G. Candore et al.

    γ-Interferon, interleukin-4 and interleukin-6 in vitro production in old subjects

    Autoimmunity

    (1993)
  • C. Caruso et al.

    Cytokine production pathway in elderly

    Immunol. Res.

    (1996)
  • S.H. Chan et al.

    Mechanisms of IFN-γ induction by natural killer cell stimulatory factor (NKSF/IL-12). Role of trascription and mRNA stability in the synergistic interaction between NKSF and IL-2

    J. Immunol.

    (1992)
  • A. D'Andrea et al.

    Production of natural killer cell stimulatory factor (interleukin-12) by peripheral blood mononuclear cells

    J. Exp. Med.

    (1992)
  • H. Gabriel et al.

    Age related increase of CD45RO+ lymphocytes in physically active adults

    Eur. J. Immunol.

    (1993)
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