Lymphokine profile in bone marrow transplant recipients

Immune reconstitution after bone marrow transplantation (BMT) recapitulates immune ontogeny. At birth there is an imbalance in lymphokine production, with decreased production of interferon-γ (IFN-γ) compared with interleukin-4 (IL-4) and IL-2. We investigated whether a similar imbalance in lymphokine production occurs in BMT recipients within 6 months after transplantation. Our results show that BMT recipients not treated with immunosuppressive drugs have a decrease in IFN-γ production and IL-2, in comparison with IL-4. This imbalance was likely to result from impaired signal transduction through surface receptors, because it was detectable on stimulation with Concanavalin A (ConA), but was overcome completely or largely by stimulation with phorbol myristate acetate (PMA) + ionophore, which bypass surface receptors and mimick the effects of second messengers. In contrast, lymphokine production in patients treated with immunosuppressive drugs (cyclosporine A, corticosteroids) was abnormal after stimulation with PMA and ionophore, as well as ConA. Thus, treated BMT recipients exhibit an additional deficit, which affects the signaling cascade downstream of second messenger generation and results in impaired lymphokine production.