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.
|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%|
|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%|