Studies on Pharmacological Activation of Human Immunoglobulin G by Chemical Modification and Active Subfragments. X. Effect of Carboxamidemethylated Fc Fragment (CM-Fc) from Human Immunoglobulin G on Delayed Type Hypersensitivity

The anti-allergic activity of the carboxamidemethylated Fc fragment (CM-Fc) from human serum immunoglobulin G (IgG) was studied using sheep red blood cell-induced delayed type hypersensitivity in mice (SRBC-DTH). CM-Fc suppressed the DTH response when administered 30 min before, or 4 h after the SRBC challenge, but not when administered 8 h or more after the challenge. The Fc fragment showed no activity. CM-Fc administration 30 min before the challenge was unable to suppress the DTH response in the cyclophosphamide (CY)-treated mice. However, adoptive transfer of splenocytes from mice treated with CM-Fc to CY-pretreated mice caused suppression of the SRBC-DTH response.These results suggest that CM-Fc suppressed the DTH response by mediating the function of CY-susceptible cells.