<qa>  What is the most immunopotent combination of probiotics?Background. Atopic diseases are increasing in countries with a Western lifestyle. The hygiene hypothesis states that the increase in atopic disease could be due to reduced exposure to microbial antigens in early in life. In search of new preventive therapies for atopic disease, exposure of pregnant women with previous or recent atopic disease, and their offspring to probiotics has been suggested. Probiotics are mono or mixed cultures of microbes which, when applied to animal or man, can beneficially affect the host, among others by inducing an immune response. Probiotics are generally accepted to be safe in children. Probiotics have shown to be effective in primary prevention of atopic disease in high-risk neonates in one study so far. However, it is still unclear by what mechanism probiotics work and which is the most immunopotent combinations of probiotics. It is likely that antigen-presenting cells APCs are involved, since these cells are important in the first line of defence in the gastrointestinal tract. It can be imagined that the immune response is the result of the interplay between probiotics and APCs. In particular, the match between pathogen-associated molecular patterns PAMPs on probiotics and their counterparts on APCs, the pathogen-recognition-receptors PRRs like for instance Toll-like receptors is decisive in this aspect. 