[1596] Strong Expression of Chemokine Receptor CCR9 in B-Cell Lymphomas Involving the Gastrointestinal Tract

Winnie Wu, Doan Ngan, Sheeja T Pullarkat. UCLA, David Geffen School of Medicine, Los Angeles, CA

Background: The gastrointestinal (GI) tract is a common site of primary extranodal B-cell lymphomas. The homing of lymphocytes to the GI tract is orchestrated by chemokines and chemokine receptors. CCR9 is a chemokine receptor expressed on gut homing lymphocytes and it exclusively binds the ligand CCL25, selectively expressed in the small intestine and plays a critical role in the homing of lymphocytes to GI tract.
We examined the differential expression of chemokine receptors in B-cell lymphomas involving the GI tract. We compared the expression of CCR9 in B-cell lymphoma involving the GI tract to primary nodal B-cell lymphomas.
Design: CCR9 expression was examined by immunohistochemistry in 18 B-cell lymphoma cases (5 diffuse large-B cell lymphoma (DLBCL), 4 mantle cell lymphoma (MCL), 9 follicular lymphoma (FL)) with GI tract involvement. 17 lymph node B-cell lymphoma cases (8 DLBCL, 1 MCL, 8 FL) were also examined. Peyer's patches served as positive control. Cytoplasmic and membrane staining in >30% of lymphoma cells was considered positive. Staining intensity was graded from 1+ to 4+ (strongest).
Results: In the GI lymphoma cases 18/18, 100% of cases demonstrated strong 4+ staining. Additionally, the lymphoma cells demonstrated much stronger staining relative to the background normal lymphoid compartment.
In contrast, among the nodal lymphoma cases 15/17 cases were negative for CCR9 staining. Of the two positive cases 2/17, the staining pattern was weak 1+ staining.

CCR9 expression in B-cell lymphomas- GI lymphomas versus Primary nodal lymphomas

GI lymphomas	CCR9 positive*	Intensity of staining**	% of cases positive
Diffuse Large B-Cell Lymphoma	5/5	4+	100%
Mantle Cell Lymphoma	4/4	4+	100%
Follicular Lymphoma	9/9	4+	100%
Primary Nodal Lymphoma	CCR9 positive*	Intensity of staining**	% of cases positive
Diffuse Large B-cell Lmyphoma	1/8	1+	12.5%
Mantle Cell Lymphoma	0/1	none	0%
Follicular Lymphoma	1/8	1+	12.5%

* >30% positive cells; ** intensity of staining 1+(weak) to 4+ (strong)


Conclusions: These preliminary results demonstrate preferential strong expression of CCR9 in B-cell lymphomas within the GI tract and may have a role in predicting GI involvement in B-cell lymphomas.
Category: Hematopathology

Monday, March 19, 2012 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 215, Monday Morning