Mechanism of immune interferon production in vitro: interaction between immune interferon-producing cells and antigenic cells.

Various processes of in vitro immune interferon production by sensitized spleen cells stimulated with allogeneic cells were investigated. When L cells, an interferon-inducing antigen, were fixed with methyl alcohol or paraformaldehyde, the ability to induce immune interferon disappeared. In this immune interferon production system, the majority of sensitized spleen cells adhered to target cells within 1 h of cocultivation. Adherence of immune interferon-producing cells to target cells was observed only when L cell-sensitized spleen cells were cocultured with L cells or with mouse embryo cells derived from C3H mice. Fixation of antigenic cells with methyl alcohol or paraformaldehyde significantly reduced cell adherence. When L cells alone or sensitized spleen cells alone were pretreated separately with cytochalasin D, neither cell type could bind to partner cells. Specific adherence did not take place at 4 degrees C, nor in the presence of dinitrophenol or sodium azide. Continuous protein synthesis in both cells was not required for immune cell adherence. Divalent cations, Ca2+ or Mg2+, were required for this immune specific adherence to take place. However, once stable adherence was established, treatment with cytochalasin D, ethylenediaminetetraacetic acid, or sodium azide, or simple reduction of temperature, did not disrupt the binding. Interaction between immune interferon-producing cells and antigenic cells can be subdivided into two phases according to the requirement for divalent cations: (i) lymphocytes and antigenic cells interact transiently, and divalent cations are required to maintain the binding; (ii) lymphocytes and antigenic cells form a stable interaction, and deprivation of divalent cations does not disrupt the binding. Colchicine showed an inhibitory effect in the period after cell-to-cell adherence. Colchicine did not inhibit the release of interferon. On the other hand, vinblastine, another antimicrotubule agent inhibited the secretion of immune interferon. Since interferon synthesis was not stopped immediately after addition of cycloheximide, continued protein synthesis of sensitized spleen cells was not required for interferon secretion. The present study showed that adherence of immune interferon-producing cells to antigenic cells was a complex phenomenon involving a series of successive events.