UPDATE 1-Swiss warn on flu vaccine with autoimmune disease

* Says autoimmune patients should not take Novartis vaccine

* Regulator says could lead to intensifying of disease

(Adds details on vaccine and warning)

ZURICH, Jan 20 (Reuters) - Switzerland's medical regulator recommended patients with serious autoimmune diseases should not use an H1N1 flu vaccine from Novartis NOVN.VX, saying there were no studies assessing the inoculation in that segment of the population.

Swissmedic said on Wednesday it could not be ruled out that either or both of the adjuvant -- which can enhance the immune response -- and the antigen, or less active ingredient, could lead to an intensifying of autoimmune diseases.

Autoimmune diseases, like rheumatoid arthritis, are caused by an overly active immune system attacking its own body, targeting substances which are normally present.

Novartis was not immediately available to comment. (Reporting by Sam Cage; Editing by David Holmes)