Inhibition of delayed hypersensitivity reactions in mice by colchicine. I. Mechanism of inhibition of contact sensitivity in vivo.

Colchicine has been recently shown to inhibit delayed hypersensitivity reactions (DHR). In the present study we investigated the effects of colchicine on contact sensitivity (CS) to dinitrofluorobenzene. Colchicine, at a dosage level of 15 micrograms/mouse, inhibited the elicitation of the contact response only when given on the day of ear challenge. Administration of the drug during the induction phase did not have any effect on the CS reaction. By using adoptive transfer experiments, we could demonstrate that CS was suppressed only when colchicine was given to the recipient mice, while treating the donors of immune lymph node cells (I-LNC) did not affect their ability to transfer a significant DHR. These findings were observed also when I-LNC were directly injected into the ears, a result which indicated that there was no effect of the drug on the ability of effector cells to migrate to the site of antigen challenge. Neither was there any effect on the distribution of T cell subsets in peripheral lymph nodes. The proliferative response of LNC to antigenic or mitogenic stimulation in vivo or in vitro was also not affected by colchicine pretreatment. These findings raise major questions about the mechanism of action of colchicine in vivo and suggest that more experimentation is required to probe the mechanism of colchicine-induced suppression of DHR.