Interferon-γ+ and interleukin-2+ T cells in peripheral blood from multiple myeloma patients in relation to disease status and maintenance therapy with interferon-α2b (intron A)

Peripheral blood T cells from 83 patients with multiple myeloma (MM) were examined for the production of interferon-γ (INFγ) and interleukin-2 (IL-2) using three-colour flow cytometry. Comparisons were made between the percentage of cytokine-positive lymphocytes in normal donors and in patients during remission or relapse. Patients were divided into those who were on maintenance therapy with interferon-α2b (intron A) and those who had no further treatment after high-dose melphalan (HDM) with or without autologous bone marrow (ABMR) or peripheral blood stem cell rescue (PBSCR). The percentage of INFγ⁺/CD3⁺, INFγ⁺/CD45R0⁺/CD3⁺ and IL-2⁺/CD8⁺ was higher in patients on INFα2b during remission and relapse compared with normal donors (P < 0.005). During remission INFγ⁺/CD45R0⁺/CD3⁺ and IL-2⁺/CD8⁺ lymphocytes were higher in patients not on INFα2b (P < 0.05 and P < 0.005, respectively). In relapsed patients INFγ⁺/CD3⁺ and INFγ⁺/CD45R0⁺/CD3⁺ were increased in patients not taking INFα2b (P < 0.005). There was no significant difference between the percentages of cytokine-positive lymphocytes in patients taking or not taking INFα2b either during remission or relapse. Plasma IL-6 levels were similar in both groups of patients during remission. The data suggest that if maintenance therapy with INFα2b induces the synthesis of INFγ and IL-2 in vivo, the magnitude of the effect is small and may be unimportant in providing an anti-tumour effect in the majority of patients.