Differential expression of cell adhesion molecules in B-zone small lymphocytic lymphoma and other well-differentiated lymphocytic disorders.

Abstract

Cell adhesion molecules (CAM) may determine the patterns of growth and dissemination of lymphoproliferative disorders. The authors have studied, by flow cytometric and immunohistochemical examination, the expression of several CAM, mediating cell-cell and cell-microenvironment interactions, on B-zone small lymphocytic lymphoma (BZSLL) and other B-cell low-grade non-Hodgkin lymphomas (NHL), including intermediate lymphocytic/mantle zone lymphoma (ILL/MZL), small lymphocytic lymphoma (SLL), and chronic lymphocytic leukemia (CLL). Relevant differences in the "adhesion phenotype" of BZSLL compared with other low-grade NHL examined were evidenced. Cells from BZSLL displayed a higher rate of expression and/or a stronger intensity of LFA-1, LFA-3, ICAM-1, and BL-CAM and a lower density of H-CAM and LAM-1 homing receptors, as opposed to SLL or CLL. A lower intensity of H-CAM along with a stronger expression of LFA-1, LFA-3, ICAM-1, and BL-CAM were also detected by comparing BZSLL with ILL/MZL: Malignant cells from BZSLL expressed Leu-CAMb determinants in three cases. BZSLL cells lacked VLA-alpha 5-integrins as opposed to CLL lymphocytes and displayed a stronger reactivity with anti-VLA-alpha 4 antibodies with respect to ILL/MZL and CLL. beta 1-integrins were consistently detected on BZSLL lymphocytes as opposed to ILL/MZL: These data suggest that the adhesion phenotype of BZSLL, by favoring homotypic and heterotypic adhesive interactions of tumor cells, might account at least in part for the peculiar intranodal compartmentalization leading to a deceptively benign (reactive) histologic appearance, and for the smoldering clinical course of this lymphoma. The pattern of CAM expression detected by the authors on malignant lymphocytes also is suggestive for a cellular origin of BZSLL from a rare subset of interfollicular or external mantle B-lymphocytes.