Suppression of contact sensitivity by IgG1 antihapten antibody. IgG1 antihapten antibody suppresses migration inhibitory factor production by lymph node cells.

Sera obtained from guinea pigs sensitized with 2,4-dinitrofluorobenzene (DNFB) showed suppressive activity on the migration inhibitory factor (MIF) production by the lymph node cells obtained from DNFB-contact-sensitized guinea pigs. A similar suppressive effect was achieved by the sera of 2,4,6-trinitrochlorobenzene- (TNCB-)sensitized guinea pigs. The suppressive factor in the sera was found to be IgG1 antihapten antibody. It suppressed MIF production dose-dependently during a period between 3 h before and 1 h after the antigen stimulation. Pretreatment of macrophages with IgG1 antihapten antibody abolished the MIF production of the lymph node cell. The antibody lost its suppressive activity after splitting off its Fc portion, and pretreatment of macrophages with Fc fragments of normal IgG1 interfered with the action of the IgG1 antibody. Therefore, the IgG1 antihapten antibody in the sera of contact-sensitized guinea pigs acted on macrophages through its Fc portion to inhibit MIF production by lymph node cells.