Suppression of contact sensitivity and cell-mediated lympholysis by oral administration of hapten is caused by different mechanisms.

Oral administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS), a water-soluble analog of trinitrochlorobenzene (TNCB), causes suppression of contact sensitivity (CS) to picryl chloride. We wished to determine what effect oral administration of TNBS (10mg), 10-12 days prior to sensitization, caused significant suppression of CS to picryl chloride. However, mice had to be fed at least three times at weekly intervals to cause suppression of the CTL response. CS was inhibited both at the afferent (induction) as well as at the efferent (effector) phase of the response. The unresponsiveness for CS was readily transferrable with cells from spleen, Peyer's patches, and mesenteric lymph node cells from fed mice. In contrast, although the hapten specific CTL response was significantly suppressed in mice fed three times. suppression could not be transferred with any of the aforementioned lymphoid populations. Furthermore, spleen cells from fed mice showed a significantly enhanced in vitro CTL response after stimulation with hapten-modified syngeneic stimulator cells. The results indicate that suppression of CS and of the CTL response in TNBS fed mice is probably caused by different mechanisms.