Abatacept Costimulatory Blockade in the Treatment of Alopecia Totalis/Universalis

Inclusion Criteria: * Must be between 18 and 75 years of age. * Must have a diagnosis of alopecia totalis or alopecia universalis * Must have \>75% total scalp hair loss at baseline as measured using the SALT score. * Duration of hair loss must be between 3 to 12 months. * There may be no evidence of regrowth present at baseline. * Subjects may be naïve to treatment or unresponsive to intralesional (IL) steroids or other treatments for alopecia areata. * Must be willing to avoid live vaccines while on the study medication, and within 3 months of its discontinuation. Exclusion Criteria: * Patients with a history of or active skin disease on the scalp such as psoriasis or seborrheic dermatitis. * Patients in whom the diagnosis of alopecia areata is in question. * Patients with active medical conditions or malignancies (except adequately treated basal or squamous cell carcinoma) that in the opinion of the investigator would increase the risks associated with study participation, including patients with a history of recurrent infections. * Patients who monitor their blood glucose levels using glucose dehydrogenase pyrrologuinolinequinone (GDH-PQQ) test strips. Blood glucose monitoring using other methods that do not react with maltose, such as the glucose dehydrogenase nicotine adenine dinucleotide (GDH-NAD), glucose oxidase, or glucose hexokinase test methods are permitted. * Patients taking TNF antagonists or other biological therapy such as anakinra. * Women of childbearing potential who are unable or unwilling to use two forms of birth control for the study duration. * Women who are pregnant or nursing. * Patients known to be HIV or hepatitis B or C positive. * Hepatitis B surface antigen positive or Hepatitis B core antibody positive at screening. * Patients with latent Mycobacterium tuberculosis infection as indicated by a positive Purified Protein Derivative \[PPD\] skin test. Subjects with a positive PPD skin test and documented completion of treatment per standard medical practice for latent TB are eligible. Subjects with a positive PPD skin test and not treated or no documentation of completion of treatment are ineligible. * History of incompletely treated Mycobacterium tuberculosis infection as indicated by: * Subject's medical records documenting incomplete treatment for Mycobacterium tuberculosis * Subject's self-reported history of incomplete treatment for Mycobacterium tuberculosis * Patients with evidence of infection or skin cancer in the treated areas. * Patients with history or evidence of hematopoietic abnormality. * Patients with history of immunosuppression or history of recurrent serious infections. * Patients with a history or likely diagnosis of COPD * Patients unwilling or unable to discontinue treatments known to affect hair regrowth in alopecia areata. * Patients who have been treated with intralesional steroids, systemic steroids, anthralin, squaric acid, DPCP (diphenylcycloprophenone), protopic, minoxidil or other medication which in the opinion of the investigator may affect hair regrowth within one month of the baseline visit.