Differential expression of sialyl and non-sialyl-CD15 antigens on Hodgkin-Reed-Sternberg cells: Significance in Hodgkin's disease

CD15 expression has been used for years to confirm the diagnosis of Hodgkin 's disease (HD). Little is, however, known on the relevance of the CD15 ant igen to the pathobiology of the disease and there is conflicting evidence a s to the prognostic value of its expression. To investigate the significanc e of the differential expression of CD15 in Hodgkin's disease, a retrospect ive study of 102 patients with "classical" Hodgkin's disease was performed. Immunohistochemical studies were carried out using antibodies against two types of CD15: non-sialylated CD15 (LeuM1 and 80H5) and sialylated CD15 (FH 6 and CSLEX1). Cases that were negative for non-sialylated CD15 or positive for the sialylated variant were stained again following neuraminidase pret reatment. The cohort included 27 patients in whom sequential biopsies were available. Both CD15 expression in its non-sialylated form and absence of s ialyl-CD15 expression correlate with a favorable outcome. Subsequent biopsies show a preferential expression of sialyl-CD15, notably in bone marrow metastases. Our findings suggest that, in the progression of HD towards a widely disseminated disease, the LewisX moiety of the CD15 an tigen on the tumor cells acquires a sialyl-group. This change may confer on the tumor cells the capacity to metastasize.