Table 2.

Major characteristic features of the alopecia areata animal models.

With autologous scalp T cells Typical properties	DEBR rat [50,51]	Classical C3H/HeJ Mice [58,59]	C3H/HeJ with skin graft-induced hair loss [52,62]	Transfer of lymph node cells of AA C3H/HeJ cultured with non-specific stimulator, to naïve mice [64]	Clonal CD8+ TCR transgenic 1MOG244.1 T lymphocyte-mediated hair loss [125]	Human AA scalp skin/SCID mice injected with scalp T cells [96]	Normal Human scalp skin/SCID* mice injected with IL-2 enriched PBMCs [102]
Skin source	Rat	Mouse	Mouse	Mouse	C57BL/6 J mice	Human	Human
Spontaneous hair growth	Positive	Positive	Positive	Positive	No data	Positive	Positive
Grooming induced hair loss	Negative	Positive	Positive	Positive	No data	Negative	Negative
Location of the infiltrates and immuno-phenotype**	Around and within the hair bulb CD8 > CD4	Above the hair bulb CD8 < CD4	Above the hair bulb CD8 < CD4	Above the hair bulb CD8 < CD4	Above the hair bulb. In severe cases-lack of follicles	Around and within the hair bulb as in human AACD8	Around and within the hair bulb as in human AA. CD8 > CD4
Applicability of model outside strain originally reported	Negative-AA susceptibility genes are either lost or recessive upon out-breeding	Rare-AA susceptibility genes are either lost or recessive upon out-breeding to most strains develop spontaneous AA	Not tested due to cross-strain transplant incompatibility	Not tested due to cross-strain transplant incompatibility	Not tested due to cross-strain transplant incompatibility	Positive-Compatible with immune-compromised recipient mouse strains	Positive-Compatible with immune-compromised recipient mouse strains
Disadvantages	Low frequency and late onset.	Low frequency and late onset	Not typical histologic feature of human AA.	Not typical histologic feature of human AA. 3. Mice environment	1. Complicated model. 2. Not typical histologic feature of human AA.	1. Many biopsies from each patient are required, 2. Complicated model	Reliance on primary human donor tissue allows no role for model propagation via mouse inter-breeding
Potential for pre-clinical drug screening	Not realistic	Not realistic	With limited value due to the murine–specific disease pathology., i.e., not responding to agents such as KV1.3	Establishing and expanding the model is possible; however, limited value due to murine –specific disease pathology, i.e., not responding to agents such as KV1.3.	Establishing and expanding the model is possible; however, limited value due to murine –specific disease pathology, i.e., not responding to agents such as KV1.3.	Not realistic	Can be used widely due to the ease of creating the model, and its reliance on healthy human donor tissue and human disease pathology.

^*C.B-17/IcrHsd-PrkdcSCIDLystbg-J mouse, the autosomal recessive beige mutation backcrossed/intercrossed to the C.B-17/Icr-Prkdcscid mouse line results in diminished NK cell activity [130].

^**Histological feature of human AA is characterized by cellular infiltrates around and within hair follicles; CD4+ cells dominants over CD8 + cells.