Immunogen sequence: YWAQGKLCCQ MCEPGTFLVK DCDQHRKAAQ CDPCIPGVSF SPDHHTRPHC ESCRHCNSGL LVRNCTITAN AECA Antigen sequence identity: Mouse 81%; Rat 81%. CD27 is a 50 kDa member of the tumor necrosis factor (TNF) receptor superfamily that includes CD40 and CD