DEMONSTRATION OF A THYMUS DERIVED, SPLENIC SUPPRESSOR CELL RESPONSIBLE FOR THE AGE-DEPENDENT DECREASE IN CONTACT HYPERSENSITIVITY IN THE ADULT-MOUSE

A suppression of contact hypersensitivity to picryl chloride has been demonstrated in adult thymectomized, 4 and 5 1/2 mo-old CBA mice after i.v. injection of spleen cells from intact CBA mice of the same age. The cells significantly suppressed the elicitation of the allergic contact sensitivity reaction and this effect could be inhibited by pretreating the cells with anti-Thy 1 serum and complement. The induction phase was found to be unaffected. However, spleen cells from donors which had received an i.v. injection of picryl sulfonic acid suppressed the induction as well as the elicitation phase of the contact dermatitis. On the basis of these results it appears reasonable to conclude that the decline in the ability to develop contact hypersensitivity in aging mice may be due to the development of a splenic suppressor T cell, mainly affecting the elicitation of the contact hypersensitivity reaction.