Lymphokines Enhance the Capacity of Human Monocytes to Secrete Reactive Oxygen Intermediates

Akira Nakagawara; Nancy M. Desantis; Nadia Nogueira; Carl F. Nathan

doi:10.1172/JCI110691

Lymphokines Enhance the Capacity of Human Monocytes to Secrete Reactive Oxygen Intermediates

Akira Nakagawara, Nancy M. Desantis, Nadia Nogueira, and Carl F. Nathan

Published November 1, 1982 - More info

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Abstract

Supernatants from mitogen- or antigen-stimulated human blood mononuclear cells enhanced the capacity of human monocytes or monocyte-derived macrophages (MDM) to release H₂O₂ or O_2̇̄ in response to phorbol myristate acetate or zymosan. The stimulatory effect of lymphokines (LK) lasted ∼5 d, regardless of the time of their addition. However, the magnitude of stimulation depended on whether LK were added to freshly explanted monocytes or to MDM. When LK were added on day 0 of culture, they enhanced MDM H₂O₂-releasing capacity ∼40% measured on day 3, when H₂O₂-releasing capacity in the controls was maximal. Addition of LK on day 2 retarded the decline in H₂O₂-releasing capacity normally seen by day 5, so that LK-treated cells released about twice as much H₂O₂ as the controls. Addition of LK to MDM that had already lost most of their H₂O₂-releasing capacity (e.g., on day 4-6) restored it to an average of 60% of the values seen with freshly explanted monocytes. In this case, LK-treated cells were about 12 times more active than cells incubated in medium alone. The effects of LK were dose- and time-dependent, with maximal effects requiring 3 d of exposure. The specific activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and myeloperoxidase, and the specific content of glutathione were not diminished in LK-treated MDM, suggesting that increased synthesis of H₂O₂ rather than decreased catabolism probably explained the greater release of H₂O₂ from LK-treated cells. In contrast, release of H₂O₂ was suppressed 93±4% by exposing monocytes for 4 d to hydrocortisone (50%-inhibitory concentration, 1.9±0.3 × 10⁻⁷ M). Thus, the oxidative metabolism of human mononuclear phagocytes can be markedly modulated in vitro: augmented by mediators released from lymphocytes during an immune response, and suppressed by antiinflammatory corticosteroids.