The purpose of this study is to evaluate the long-term safety and profile of psoriasis patients who have completed participation in a previous study and who received treatment with MEDI-507.

This study will evaluate the long-term safety and lymphocyte repletion profile of psoriasis patients who have completed participation in a previous study and who received treatment with MEDI-507. Patients must have had an ALC > 30% lower than baseline (defined as baseline prior to any MEDI-507 exposure); or an absolute CD4 count of < 250 cells/uL. This study will also evaluate the development and durability of anti-MEDI-507 antibodies.

Inclusion Criteria:

• The patient has previously completed participation (i.e., completed per protocol, including any long term follow-up; or discontinued from the study due to withdrawal of consent, loss to follow-up, or other reason) in a Medimmune, Inc. study of MEDI-507 in psoriasis in which they received MEDI-507 (or placebo for patients who participated in a blinded placebo-controlled study of MEDI-507, and for whom the treatment assignment in that study has not been unblinded at the time of entry into this study)
• The patient had an absolute lymphocyte count (ALC) > 30% lower than baseline (defined as baseline prior to any MEDI-507 exposure; or, for patients whose treatment assignments have not been unblinded at the time of entry into this study, drug exposure) at his/her final visit (excluding any long-term follow-up visits) in the most recent Medimmune, Inc. study in which the patient participated; or the patient had an absolute CD4 count of < 250 cells/uL at his/her final visit (including any protocol-specific long-term follow up) in the most recent Medimmune, Inc. study in which the patient participated.
• Written informed consent obtained from the patient

Exclusion Criteria:

• There are no exclusion criteria.

Patient has previously completed participation