The MastAttack 107: The Layperson’s Guide to Understanding Mast Cell Diseases, Part 57

71. What other diseases “look like” mast cell disease?

Mast cell diseases have many symptoms that are also commonly found in other disorders. This is one of the reasons why it is difficult to diagnose correctly. The following conditions have symptoms that can look like mast cell disease.

Neuroendocrine cells are specialized cells that help to pass signals from the nervous system to nearby cells, causing those cells to release hormones. There are many types of neuroendocrine tumors. Some conditions that look like mast cell disease are caused by these tumors. Symptoms from them are caused by the response of too much hormone.

Carcinoid syndrome is the result of a rare cancerous growth called carcinoid tumor. This tumor releases too much serotonin into the body. This can cause flushing, nausea, vomiting, diarrhea, difficulty breathing, and cardiovascular abnormalities such as abnormal heart rhythm. Mast cells also release serotonin but they release much less than carcinoid tumors.

VIPoma means vasoactive intestinal peptide –oma. When a word has –oma at the end, it means that it is a tumor. A VIPoma is a tumor that starts in the pancreas. It releases a chemical called vasoactive intestinal peptide. VIPoma can cause flushing, low blood pressure, and severe diarrhea leading to dehydration. A VIPoma can also abnormalities in the composition of the blood. Many patients have low potassium, high calcium, and high blood sugar.

Pheochromocytomas start as cells in the adrenal glands. They release excessive norepinephrine and epinephrine. They can cause headaches, heart palpitations, anxiety, and blood pressure abnormalities, among other things.

Zollinger-Ellison syndrome is a condition in which tumors release too much of a hormone called gastrin into the GI tract. This causes the stomach to make too much acid, damaging the stomach and affecting absorption.

Some blood cancers can cause mast cells to become overly activated. They may also cause an increase in tryptase, an important marker in diagnosing systemic mastocytosis.

Some other cancerous tumors like medullary thyroid carcinoma can cause mast cell type symptoms including flushing, diarrhea, and itching.

Most diseases with any allergic component can look like mast cell disease.

Eosinophilic gastrointestinal disease occurs when certain white blood cells called eosinophils become too reactive, causing inflammation to many triggers. Furthermore, people are more frequently being diagnosed with both EGID and mast cell disease.

Celiac disease is an autoimmune disease in which gluten causes an inflammatory reaction inside the body. The damage to the GI tract can be significant. Malabsorption is not unusual. Children with celiac disease may grow poorly. Bloating, diarrhea, ulceration, and abdominal pain are commonly reported.

FPIES (food protein induced enterocolitis syndrome) can cause episodes of vomiting, acidosis, low blood pressure and shock as a result of ingesting a food trigger.

Traditional (IgE) allergies can also look just like mast cell disease. They are usually distinguished by the fact that mast cell patients may react to a trigger whether or not their body specifically recognizes it as an allergen (does not make an IgE molecule to the trigger). Confusingly, it is possible to have both traditional IgE allergies and mast cell disease.

Postural orthostatic tachycardia syndrome (POTS) is commonly found in patients with mast cell disease. However, POTS itself can have similar symptoms to mast cell disease. Palpitations, blood pressure abnormalities, sweating, anxiety, nausea, and headaches are some symptoms both POTS and mast cell disease have. There are also other forms of dysautonomia which mimic the presentation of mast cell disease.

Achlorhydria is a condition in which the stomach does not produce enough acid to break down food properly. This can cause a lot of GI pain, malabsorption, anemia, and weight loss.

Hereditary angioedema and acquired angioedema are conditions that cause a person to swell, often severely. Swelling may affect the airway and can be fatal if the airway is not protected. Swelling within the abdomen can cause significant pain and GI symptoms like nausea and vomiting.

Gastroparesis is paralysis of the stomach. People with GP often experience serious GI pain, vomiting, nausea, diarrhea or constipation, bloating and swelling.

Inflammatory bowel diseases and irritable bowel syndrome can all cause GI symptoms identical to what mast cell patients experience.

This list is not exhaustive. There are many other diseases that can look similar to mast cell disease. These are the ones I have come across most commonly.

For more detailed reading, please visit the following posts:

Gastroparesis: Part 1
Gastroparesis: Treatment (part 2)
Gastroparesis: Diabetes and gastroparesis (Part 3)
Gastroparesis: Post-surgical gastroparesis (Part 4)
Gastroparesis: Less common causes (Part 5)
Gastroparesis: Autonomic nervous system and vagus nerve (Part 6)
Gastroparesis: Idiopathic gastroparesis (Part 7)

Food allergy series: Food related allergic disorders
Food allergy series: FPIES (part 1)
Food allergy series: FPIES (part 2)
Food allergy series: Eosinophilic colitis
Food allergy series: Eosinophilic gastrointestinal disease (part 1)
Food allergy series: Eosinophilic gastrointestinal disease (part 2)
Food allergy series: Eosinophilic gastrointestinal disease (part 3)
Food allergy series: Eosinophilic esophagitis (Part 1)
Food allergy series: Eosinophilic esophagitis (Part 2)
Food allergy series: Eosinophilic esophagitis (Part 3)

Angioedema: Part 1
Angioedema: Part 2
Angioedema: Part 3
Angioedema: Part 4

Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 1
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 2
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 3
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 4
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 5
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 6
Deconditioning, orthostatic intolerance, exercise and chronic illness: Part 7

Immunoglobulin free light chains: A possible link between autoimmune disease and mast cell activation

An antibody (also called an immunoglobulin) is shaped like a Y.  The base of the Y is called the Fc region.  The arms of the Y are made of pieces called light chains and heavy chains.  Light chains (described as K or λ) have variable sequences that allow the complete antibody to stick to specific things, like bacteria or allergens.  Light chains are part of how your body fights infections and responds to allergens.  Importantly, free light chains do not work as antibodies.  They are not able to stick to the target the way the total antibody can.

Antibodies are made by white blood cells called plasma cells, which are B cells that circulate and release antibodies as needed.  When producing antibodies, B cells normally make more light chains than heavy chains.  Only about 60% of the light chains made are needed to produce antibodies.  The rest of the light chains are released into plasma and are present there for 2-6 hours, until they are cleared by kidneys.  Light chains that are released into plasma are called immunoglobulin free light chains, shortened as Ig-fLCs.

Another way Ig-fLCs are formed is when they antibody is bound and degraded by a cell.  Antibodies bind things like allergens.  Once they bind allergens (or something else), the antibodies can then bind to receptors on the outside of cells to tell the cells what they found.  Once the antibody is bound to the receptor, it can be partially broken down.  However, light chains are not damaged in this process, and they may be released back into serum.

Ig-fLCs are the subject of ongoing research in various disease models.  Ig-fLC elevation has been linked to a number of inflammatory conditions, including autoimmune diseases.  Systemic lupus erythematosus (SLE) patients demonstrate a significant elevation of Ig-fLCs in urine 4-8 weeks prior to a symptomatic flare.  SLE is an antibody driven disease and the extra Ig-fLCs may be produced as a byproduct of making more autoantibodies in advance of a flare.  In this capacity, it would demonstrate hyperactivity of the B cells that make the autoantibodies.

Ig-fLCs were also found to be elevated in 1/3 patients with rheumatoid arthritis and 1/5 patients with systemic sclerosis.  A number of cancers also induce elevation of Ig-fLCs.

Ig-fLCs are involved in a number of allergic processes.  In allergic asthma animal models, Ig-fLCs have been found to induce bronchoconstriction and acute mast cell degranulation.  Using an experimental light chain antagonist can prevent this reaction.  Κ light chains are elevated in serum of asthmatics, regardless of whether or not the asthma is atopic is nature. λ light chains are not elevated in this population.

Ig-fLCs are also involved in other allergic mouse models, including contact dermatitis, food allergy and inflammatory bowel disease.  In these models, the Ig-fLCs can sensitize mast cells to allergens so that exposure to the allergen causes mast cell activation and degranulation.

Ig-fLCs have also been implicated in mast cell dependent colitis and inflammatory bowel diseases such as ulcerative colitis and Crohn’s.  It is believed that antigen specific Ig-fLC sensitizes mast cells to cause activation and degranulation.  This is especially important because it describes a mechanism that occurs in the absence of IgE.  Serum κ and λ light chains are elevated in Crohn’s models and using an experimental blocker prevents these bowel symptoms.  Research has indicated that the IgE, IgG and paired Ig-like receptor A receptors are not involved in binding Ig-fLCs in these models.

Many mast cell patients have a primary inflammatory condition, such as IBD or autoimmune disease.  Mast cell activation via Ig-fLCs is, to me, the most plausible explanation for this relationship.  Currently, mast cell activation by Ig-fLCs has not been demonstrated in humans, though present in many animal models.  However, Ig-fLC correlation to autoimmune diseases such as lupus has been shown in humans.

References:

Kraneveld A, et al. Elicitation of allergic asthma by immunoglobulin free light chains. PNA 2005: 102(5); 1578-1583.

Thio M, et al. Antigen binding characteristics of immunoglobulin free light chains: crosslinking by antigen is essential to induce allergic inflammation. PLoS One 7(7): e40986.

Rijnierse A, et al. Ig-free light chains play a crucial role in murine mast cell-dependent colitis and are associated with human inflammatory bowel diseases. J Immunol 2010; 185:653-659.

Gottenberg JE, et al. Serum immunoglobulin free light chain assessment in rheumatoid arthritis and primary Sjogren’s syndrome. Ann Rheum Dis 2007; 66:23-27.

Aggarwal R, et al. Serum free light chains as biomarkers for systemic lupus erythematosus disease activity. Arthritis Care and Research 2011: 63(6): 891-898.