Systematic mast cell activation diseases (MCAD) comprise the three subgroups: mast cell activation syndrome (MCAS), systematic mastocytosis (SM) and mast cell leukemia (MCL), whereby only MCAS has a relatively high prevalence of about 5-17%.
MCAD can cause a wide symptomatology and thereby strongly affect the well-being. In recent findings, it turned out that MCAD seem to be the underlying cause for chronic-inflammatory diseases and other conditions of unclear origin.
Causes and disease mechanism
One single mutated precursor cell in the bone marrow multiplies and produces a large number of pathologically altered mast cells (a type of immune cell) with an activating mutation. One or several organs may then be infiltrated by those mutated mast cells. This leads to an enhanced release of histamine and other mediators in affected tissues and organs. In some cases, the activation is of permanent manner, in others, it is more an enhanced susceptibility to be activated by external triggers. Certain mutations which are known to be mast cell activating, can be found only in rare cases. In most cases, however, the physical cause of mast cell activation is still unknown.
Depending on the organs affected by the altered mast cells, a wide range of different symptom constellations and severity of symptoms may be triggered. They often resemble those of an allergy or a chronic-inflammatory disease, a cold or food poisoning. Depending on their severity they can lead to exhaustion or an inability to work, and in some cases even to an anaphylactic shock. The symptoms are, however, rarely consistent.
The largest problem is to consider the possibility of MCADs in the first place. The disease is not characterized by consistent symptoms. The responsible genetic mutations seem to be only partially known. The existing diagnostic methods are not specific enough yet. MCAD can be detected in some cases, but they can not be excluded if the result is negative. For example, the detection of enhanced mediator concentrations often fails for several reasons. This means that in most cases a MCAD can not be diagnosed convincingly. But there is a therapy, which usually works well and which nevertheless should be tried out over a limited period of time. If the patient responds well, it should be continued.
From what we know today, the underlying causes of MCADs cannot be tackled and cured. There is little prospect that a patient will spontaneously recover, but the symptoms can mostly be controlled therapeutically.
The therapy of MCADs primarily consists of avoiding the triggers and patients mostly need to be supported by medication.
Many chemical, physical, psychological and endogenous triggers and pathogens are able to activate pathologically altered mast cells and stimulate them to release mediators. These stimuli are dose-dependent. They have to be avoided to the extent that the people concerned are feeling well and are not suffering from any symptoms. Especially, many food products and additives are either mast-cell-activating or histamine-containing. They should be tentatively avoided. Should the condition turn out to be triggered by the ingestion of certain foods, the elimination diet should be continued in longer term.
Medication aims to stabilize the mast cells (mast cell stabilizers), to inhibit the synthesis of the main mediators (e.g. prostaglandin synthesis inhibitors), and to block the effect of the liberated mediators (histamine receptor antagonists). The remaining ailments may be treated symptomatically.
It should be noted that many drug substances and excipients are badly tolerated and should be avoided (see our lists).