What are the characteristics of the immune system in urochordates?

I- Urochordates have a relatively complex self/non-self discrimination system.
II- Ascidians have a genetic control of allorecognition, which is comparable to the major histocompatibility complex (MHC) of vertebrates.
III- Urochordates have a highly developed acquired immune system.
IV- Urochordates share innate immunity mechanisms with vertebrates.