Update on immunofluorescent testing in bullous diseases and lupus erythematosus.

One of the earliest methods for investigating the immunologic basis of disease was the use of immunofluorescence (IF) on skin biopsy specimens and serum. IF can be used to detect immunoglobulins, complement components, and fibrin. In some diseases, the IF findings are disease specific and diagnostic, especially in certain bullous diseases. The use of IF testing has increased with the recent development of the salt split skin technique. The newer IF findings in some well-established immunodermatologic diseases and several recently described diseases are discussed. A brief description of the techniques involved in direct and indirect IF is also presented.