"Mast Cell Disorder to be Ruled Out in MCS"
Gunnar Heuser
To the editor.--"Mast Cell Disorder to be Ruled Out in MCS." I make reference to the "1999 Consensus Statement" on Multiple Chemical Sensitivities (MCS),[1] which was also signed by me. In this statement, mastocytosis and porphyria are excluded from a diagnosis of MCS. However, in that statement, we are not instructed to rule out these diseases in every case that presents with chemical sensitivity nor are guidelines given as to the steps necessary to diagnose these diseases.
In 1996, I postulated that chemical exposure can trigger a mast cell disorder, which in turn can explain the mechanism of MCS.[2] Subsequently, I have studied 38 patients with a history of chemical injury and resultant MCS. Complaints frequently included flushing, a metallic taste, and significant other reactions in response to even small amounts of chemicals. Skin biopsies were obtained on all 38 patients, and they were stained with Glemsa and regular stains. All specimens were sampled from the shoulder blade areas by a board-certified dermatologist, and they were interpreted by a board-certified dermatopathologist. All biopsies were taken from skin normal in appearance and from patients with no subjective complaints (e.g., itching, burning). Twenty-seven specimens were diagnosed as "perivascular dermatitis." Twenty specimens showed a positive Glemsa stain with increased numbers of mast cells. These conditions are compatible with a mast cell disorder.
During the past several months we have submitted blood specimens for determination of tryptase to Dr. Schwartz's laboratory in Boston, Massachusetts. Some of these specimens were also positive and, therefore, suggestive--if not diagnostic--of a mast cell disorder. Dr. Schwartz's laboratory recently[3] provided data that indicated that typtase is stored and discharged by mast cells and that levels of [Alpha]-protryptase reflect total body burden of mast cells, whereas [Beta]-tryptase levels reflect the magnitude of mast cell activation.
The diagnosis of a mast cell disorder[4,5] is not an easy one inasmuch as various target organs (e.g., skin, bone marrow, intestinal mucosa, blood) may show fluctuating findings. For example, one patient of mine had elevated tryptase levels, whereas a skin biopsy was negative for mast cells. Another patient had elevated typtase levels on more than one occasion, whereas a bone marrow study was negative, and a skin biopsy was positive. It should also be noted that the results of biopsy findings very much depend on staining techniques that may, at times, be inadequate for one to truly appreciate the number of mast cells--specifically the mast cells that have undergone degranulation.
I have embarked upon a cooperative effort with Dr. Schwartz and with Professor Johansson at the Karolinska Institute in Stockholm, Sweden. Professor Johansson[6,7] will examine our skin-biopsy specimens for mast cell and related activities. He will add stains for histamine and other compounds to further delineate and define the concept that chemical exposure can trigger a mast cell disorder.
Mast cells also play an intriguing and perhaps significant role in the central nervous system.[4,8,9] Whether they interact with the limbic system, especially the extended amygdala region, is unknown. This question is of interest because we[10] have found increased metabolic activity (determined by glucose uptake on positive emission tomography [PET] scanning)in these regions in patients with a history of chemical history and resultant MCS. Our PET findings support the concept of kindling in MCS and potentially explain the emotional lability of patients with MCS inasmuch as the amygdala adds emotion to sensory inputs.
Although patients with established mastocytosis are often very sensitive to chemicals, I am not, at this time, postulating that our patients with MCS have mastocytosis. Instead, I propose that chemical exposure can result in an acquired mast cell disorder, which in turn explains at least one mechanism of MCS. The mast cell disorder and the mechanism by which it causes MCS obviously need to be defined further.
At my suggestion and upon that provided by several patients, the Mastocytosis Society has sent a questionnaire to all its patient members. The questionnaire addresses if they are sensitive to chemicals and solicits additional information. The results of this survey should be available soon.
The diagnosis of mast cell disorder is an important one inasmuch as it calls for specific treatment, which may be symptomatically successful. In view of our preliminary data, such a diagnosis should, therefore, be considered in every patient with MCS.
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References
[1.] Bartha I, Baumzweiger WM, Buscher DS, et al. Multiple chemical sensitivity: a 1999 consensus. Arch Environ Health 1999; 54:147-49.
[2.] Heuser G, Kent P. Mast cell disorder after chemical exposure. 124th Annual Meeting. Am Public Health Assoc (New York), 1996.
[3.] Kanthawatana S, Carias K, Arnaout R, et al. The potential clinical utility of serum alpha-protryptase levels. J Allergy Clin Immunol 1999; 103:1092-99.
[4.] Metcalfe DD, Baram D, Mekori YA. Mast cells. Physiol Rev 1997; 77:1033-79.
[5.] Metcalfe DD. Mastocytosis syndromes. In: Middleton E, Reed CE, Ellis EF, et al. (Eds). Allergy: Principles and Practice, 5th ed. St. Louis, MO: C.V. Mosby Co., 1998; pp 1093-1103.
[6.] Gangi S, Johansson O. Skin changes in "screen dermatitis" versus classical UV- and ionizing irradiation-related damage-similarities and differences (review article). Exp Dermatol 1997; 6:283-91.
[7.] Rossi R, Johansson O. Cutaneous innervation and the role of neuronal peptides in cutaneous inflammation. Europ J Dermatol 1998; 8:299-306.
[8.] Dines KC, Powell HC. Mast cell interactions with the nervous system: relationship to mechanisms of disease. J Neuropathol Exp Neurol 1997; 56(6):627-40.
[9.] Olness K, Hall H, Rozniecki JJ, et al. Mast cell activation in children with migraine before and after training in self-regulation. Headache 1999; 39:101-07.
[10.] Heuser G, Wu JC. Limbic hypermetabolism in patients with chemical intolerance. Human PET studies. New York Academy of Sciences Conference on the Role of Neural Plasticity in Chemical Intolerance. New York: June 16-19, 2000.
Gunnar Heuser, M.D., Ph.D., F.A.C.P. Agoura Hills, California
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