Bullous Pemphigus rationale for treatment ?

MTB 3 states that BP is treated with tetracycline and erythromycin + nicotinamide as alternatives to steroids .
I dont understand the rationale behind this treatment .There is no bacterial cause behind this autoimmune disease to begin with .

Can anyone share their views please ?

Source: Student Doctor Network - June 18, 2016 Category: Universities & Medical Training Authors: zeevee Source Type: forums