An assembly of ultraviolet A (UVA)-emitting tubular strip lights that is an exchangeable component of a photopheresis system, and used to irradiate blood components during extracorporeal photoimmunetherapy to treat immune disorders, especially cutaneous T-cell lymphoma (CTCL). It typically consists of a replaceable assembly having a bank of several lamps that are electronically monitored and tracked by the main unit, so that notification of pending replacement after the recommended usage time (e.g., 150 hours) is provided to the operator of the system.