The response of normal, thymectomized and reconstituted mice in contact sensitivity.

Normal, deprived' (thymectomized, irradiated, bone marrow injected) and reconstituted' (thymectomized, irradiated, bone marrow injected, thymus grafted) CBA mice have been tested for their ability to respond to the contact sensitizing agent, oxazolone. The test involved painting the ear of a previously sensitized animal and subsequently measuring alterations in ear thickness. A sensitized condition could be detected in the normal and reconstituted mice after either one or two sensitizing contacts with oxazolone but in the deprived animal little or no sensitivity could be detected. It is concluded that the thymus influences the development of contact sensitivity probably by provision of a population of reactive cells.