RE: [Histonet] Tryptase Stain for Mast Cell in Gastrointestinal Specimens

From:Julia Dahl

The use of mast cell tryptase has recently been touted to identify patients with diarrhea who may respond to anti-histamine treatment.  This has been promulgated in advertisements to gastroenterologists - with the test being called a unique test offered by this ONE laboratory - the "ID-ME" test, as a test specific for mastocytic enterocolitis.

The study was presented at the 2004 USCAP meeting and has not yet been widely accepted.  

Archives of Pathology and Laboratory Medicine: Vol. 130, No. 3, pp. 362C367.Mastocytic Enterocolitis: Increased Mucosal Mast Cells in Chronic Intractable Diarrhea
 Shriram Jakate, MD, FRCPath;  Mark Demeo, MD;  Rohan John, MD;  Mary Tobin, MD;   Ali Keshavarzian, MD

the Departments of Pathology (Drs Jakate and John) and Medicine (Drs
Demeo, Tobin, and Keshavarzian), Rush University Medical Center,
Chicago, IllAccepted October 28, 2005
Here is the Materials and Methods section:

Forty-seven patients (32 women and 15 men; age range, 21-78 years) were
diagnosed as having chronic persistent diarrhea of unknown cause at our
institution between 2000 and 2004. All patients underwent the
investigational protocol recommended by the American
Gastroenterological Association. A comprehensive history was obtained
that included the onset, pattern, and duration of symptoms, as well as
the presence or absence of fecal incontinence, abdominal pain, weight
loss, medication use, recent travel, diet, and stress. A physical
examination was conducted to assess the extent of fluid loss, as well
to evaluate rashes, flushing, oral ulcers, edema, perianal skin, anal
sphincter tone, abdominal masses, and ascites. Complete blood counts
and a basic metabolic panel (serum sodium, potassium, chloride, carbon
dioxide, glucose, calcium, urea nitrogen, and creatinine) were
performed. A stool analysis assessed the type and severity of diarrhea
and the presence of ova and parasites. In addition, the patients
underwent full colonoscopy (22/47 patients), upper endoscopy (20
patients), or both (5 patients), with random biopsy samples taken from
the colon and from the second part of the duodenum. The random colonic
biopsies included 4 to 10 pieces taken from the right and left colon
and submitted in one container, and the random duodenal biopsies
included 2 to 5 pieces taken mainly from the second part of the
duodenum and submitted in one container. The colonic and duodenal
biopsy specimens were processed for routine histologic examination with
standard formalin fixation and paraffin embedding, and 5-m-thin
sections were stained with hematoxylin-eosin. In addition, all sections
were immunohistochemically stained for MCT as follows: 4-m-thin
sections were cut, dried, and deparaffinized before placing them on the
Ventana NexES autostainer (Ventana Medical Systems Inc, Tucson, Ariz),
where they were treated with protease 1 for 4 minutes and then
incubated with monoclonal mouse anti-human MCT (clone AA1, code M 7052;
DAKO, Carpinteria, Calif; dilution 1: 1600) for 32 minutes. A
recommended negative control was used. Visualization was performed
using the iView DAB detection kit (Ventana Medical Systems Inc).

The results: 
Thirty-three (70%) of 47 study patients with chronic intractable
diarrhea had increased mast cells (mean  SD, 25.7  4.5 cells per
high-power field) (Figure 5 ). Figure 6 
illustrates the mean  SD concentrations of mast cells in the control
subjects, in the patients with diarrhea caused by specific diseases,
and in the study patients with chronic intractable diarrhea. Among the
5 patients who underwent both colonic and duodenal biopsies, the
increase in mast cells observed in 3 patients was seen in both organs,
suggesting a diffuse enterocolonic mucosal increase. Among all biopsy
samples in which there was an increase in mast cells, the increase was
generally diffuse in the mucosa, with little elevation in the
concentration of submucosal mast cells (Figure 7 ),
with no sex differences observed in the control versus the affected
populations. At follow-up, 22 (67%) of 33 study patients who received H1 and H2
receptor antagonists with or without mast cell mediator release
inhibitor showed cessation of diarrhea or significant reduction in
diarrhea (defined as 50% reduction in stool frequency or as 50% improvement in stool consistency).

It states the type of antibody used for the study, above.

While the study is interesting, it does not allow the distinction between whether the mast cells are the cause of the diarrhea or just a participant in whatever the process that is causing the diarrhea is.

A specific problem with the study is that patient's biopsy sites were not specifically separated by right colon or left colon to determine statistical significance.  Inflammatory cells of ALL TYPES are considerably more dense in the right colon and varies significantly with age.  This study could simply have documented more mast cells in the patients whose right colon was biopsied more than the left colon.  

There are many reasons why patients could be responding to the drugs, as well - and they may or may not have ANYTHING to do with the presence or absence of mast cells.  For instance for H1 reversible competitive antagonists of histamine at H1 
        receptor sites: They do not prevent histamine release or bind to the histamine 
        that has already been released. The H1 receptor 
        blockade results in decreased vascular permeability, reduction of pruritus 
        and relaxation of smooth muscle in the respiratory and gastrointestinal 

That these patients respond to the drug could be an incident of TRUE, TRUE and UNRELATED.

Because there is a "new" advertised test going out to your clinicians, gastroenterologists may be asking your pathologists about whether or not they do this test.  They may think that your pathologists aren't staying up to date because they don't offer it.

As a GI pathologist, I don't offer this test unless requested.  I spend time with my clinicians telling them why I don't do the test.  

If they still want the test, I insist that they do the following:  EGD with biopsies of small bowel, antrum and body (to evaluate for other causes of diarrhea) and colonoscopy with biopsied of TI, right colon and left colon SEPARATELY, and rectum.  With those 7 biopsies, I can generally tell them why the patient has diarrhea - and if they comply with the Right versus LEFT colon, I can show them the mast cell difference between right and left colon and let them decide whether or not to try antihistamines - for whatever reason.

Off my soap box now, 

Julia Dahl, M.D.
Medical Director
Mosaic GI-Hepatic Pathology Services
Collierville, TN

> Date: Fri, 26 Oct 2007 06:08:15 -0700
> From:
> To:;
> Subject: Re: [Histonet] Tryptase Stain for Mast Cell in Gastrointestinal	Specimens
> CC: 
> We use Abcam ab2378 for human and monkey tissue with anti mouse polymer from dako and it works very well.
> Shelly Coker  wrote:  Hello everyone,
> Our pathologist has asked me to inquire about a Tryptase stain for mast cell tumors in gastro specimens. She said is one of those "latest/greatest" things. Does anyone have any experience with this stain?
> Thanks,
> Shelly 
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