Dobri Kiprov, one of the co-authors, probably noticed the effect first. AFAIK he noticed that people who were recipients of TPE (Therapeutic Plasma Exchange) t

Dobri Kiprov, one of the co-authors, probably noticed the effect first. AFAIK he noticed that people who were recipients of TPE (Therapeutic Plasma Exchange) tended to have significantly fewer common colds, which indicated an improvement of the immune system function.