-stimulated by external stimuli 

-guided by switch regions

-with exception of IgD, is irreversible

-transcription starts

-transcription separates DNA into single strands called R loops

-AID recognizes R-loops and initiates creation of nicks

-repair proteins recognize nicks and bring together the switch regions

-intervening DNA is excised

-opsonization

-neutralization

-activate classical complement cascade

-determine titer

-calculate geometric mean of titer