Clinical aspects of patients with MCS - from the standpoint of allergy]

BACKGROUND: "Sick House Syndrome" is thought to be an illness caused by indoor environments such as allergens, bacteria and chemical compounds. But it is not yet an established clinical entity. "Sick House Syndrome" overlaps in part with Multiple Chemical Sensitivity (MCS) whose symptoms are induced by very small amount of volatile chemical compounds. METHODS: We selected possible cases of MCS from patients who visited our specially built facility for"Sick House Syndrome" by tentative criteria as follow: (1)histories of chemical compounds exposure, (2)multi-organ symptoms, (3)exclusion of other disease(s) which may be responsible for symptoms, (4)chronic symptoms. Clinical aspects of the possible cases were examined. RESULTS: Fifty out of about 130 patients were the possible cases of MCS, 38 females and 12 males, aged 15 to 71 years old. Forty two out of 50 patients (84%) had a history and/or a complication of allergic diseases. This rate is much higher than the rate of prevalence of allergic diseases in Japanese population. Allergic rhinitis was the most popular allergic disease in the possible cases. Total IgE values were relatively low, 32 patients (64%) showed the IgE value below 200 IU/ml. No patients showed anti-formaldehyde IgE antibody. Decreased reactivity and decreased sensitivity of histamine release from peripheral blood were observed after challenge tests with chemical compounds. CONCLUSION: Allergic reactions can not be the causative mechanism(s) of the MCS, which is induced by multiple and different chemical compounds. Our results, however, suggest that patients having allergic diseases may be easily suffered from MCS or MCS may strengthen symptoms of allergic diseases.