Induction of hair regrowth in the alopecia site of IFN-gamma knockout mice by allografting and IFN-gamma injection into the transplantation site.

We previously demonstrated that around 6 weeks of age most of the interferon-gamma (IFN-gamma)(-/-) but none of the IFN-gamma(+/+) C57BL/6 mice began to lose hair in their dorsal or occipital areas or both and that a single s.c. injection of IFN-gamma into IFN-gamma(-/-) mice at 3 but not at 8 weeks of age (or later) could protect all the mice from alopecia.

Alopecia of IFN-gamma knockout mouse as a model for disturbance of the hair cycle: a unique arrest of the hair cycle at the anagen phase accompanied by mitosis.

Interferon-gamma(-/-) (IFN-gamma(-/-)) and IFN-gamma(+/+) C57BL/6 mice (3 weeks of age) completed the production of morphogenesis-derived hair. Around 6 weeks of age, however, most of the IFN-gamma(-/-) but none of the IFN-gamma(+/+) mice began to lose hairs in the dorsal and occipital areas in the absence of inflammatory reactions, and the alopecia was sustained for at least several 10-week periods of observation. A single subcutaneous injection of IFN-gamma to IFN-gamma(-/-) mice at 3, but not 4, 5, or 8 weeks of age could protect all the mice from alopecia, revealing that the lack of IFN-gamma around 3 weeks of age is directly responsible for the alopecia.