Immunological competence in Snell‐Bagg pituitary dwarf mice: Response to the contact‐sensitizing agent oxazolone

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Abstract
Snell‐Bagg pituitary dwarf mice are an autosomal recessive mutant, their dwarfism being the result of an anterior pituitary defect. A number of investigators have reported that these mice, in addition to having hormonal deficiencies, have immunological defects. Dwarf mice reject allogenic skin grafts slowly, show a reduced response to contact agents and decreased graft‐vs.‐host reactivity. Other investigators have suggested that these results indicate a thymus‐cell‐deficiency. Contrary to this conclusion, we have found that the thymuses in our dwarf mice have a normal cellular composition and the T‐cell‐dependent zones in the peripheral lymphoid tissues are not deficient in lymphocytes. Therefore, this investigation was undertaken to study the response of dwarf mice to the hapten, oxazolone, which produces one type of T‐cell‐dependent response, delayed hypersensitivity, and to compare this response to that of normal littermates in animals 15 to 90 days of age. The results of these studies indicate that the dwarf mice have the ability to develop delayed hypersensitivity, as shown by both a blastogenic response in the lymph node draining the site of sensitization (the induction phase of delayed hypersensitivity) and by a positive skin‐test. The magnitudes of the blastogenic response and the skin‐test reaction appear similar in dwarf and normal littermate animals, both histologically, and quantitatively. These results, which are in contrast to other studies, may be the result of the husbandry provided our colony of dwarf mice, and the immunological deficiencies that have been described previously may not be a necessary condition accompanying dwarfism in these mice.
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