From wikipiedia: "Lactobacillus casei is a transient, anaerobic microorganism of genus Lactobacillus found in the human intestine and mouth. As a lactic acid producer, it has been found to assist in the propagation of desirable bacteria. This particular species of lactobacillus is documented to have a wide pH and temperature range, and complements the growth of L. acidophilus, a producer of the enzyme amylase (a carbohydrate-digesting enzyme). It is known to improve digestion and reduce milk intolerance and constipation." Yeah, it's real, but "Immunitas" is a trade mark of "Dannon" (also known as "Danone") for their particular strain of the bacteria.

l. casei immunitas has a purpose to lead people to think that this product has something that we all need that we can not get elsewhere and that is a lie!

OK guys, this is something that was studied extensively by Cornell (my alma mater). Lactobacillus is present in yogurt (this is how yogurt is made). And yes, it is a probiotic (latin "good [living] bacteria") culture; this means it assists your immune system (and digestion) via living, primarily, in your jejunum as opposed to the duodenum (in small intestine). By metabolizing macromolecules within this structure, the uptake (one function of the jejunum) into the bloodstream of nutrients via the capillary beds circa the small intestine facilitates transport and exposure (of lymphatic system) to weakened strains of certain bacteria that may be similar to some that make us sick. In this manner, the consumption of the Lactobacillus in yogurt acts much as an immunization at the doctor's office. Thus, eat some yogurt a few times per week to keep up your immune system (some cardio- activity never hurts, either). However, yes, this is a stupid marketing strategy. It is nothing different than what you will get in regular yogurt (50 cents per cup???) as opposed to their $3.00 bottle. It's an attempt to make money, guys. Fellow biologists and anatomists feel free to join me. ...Hope that was simple enough to understand