A CD2-BLOOD LYMPHOCYTES FROM PATIENTS WITH SEZARY SYNDROMES OVEREXPRESS THE LOW-MOLECULAR-WEIGHT GTP-BINDING PROTEIN RAB2( SUBSET OF NONMALIGNANT PERIPHERAL)

The Rab branch of the Ras-related GTP/GDP-binding proteins currently i ncludes st least 25 related members which are involved in the intracel lular vesicular transport along the secretory and endocytic pathways i n eukaryotic cells. The overexpression of the Rab2 protein in peripher al mononuclear cells is demonstrated from 13 out of 17 patients exhibi ting a Sezary syndrome. Moreover, this phenomenon is detectable in oth er lymphoid and myeloid malignancies. Several lines of evidence are sh own suggesting that the Rab2 overexpression can be related not to leuk emic cells but to a subset of peripheral lymphocytes with a CD2 + phen otype. Our results provides strong evidence for the implication of a s mall GDP/GTP-binding protein in immunological events associated with n eoplastic states. The precise cellular population involved in this pro cess remains to be determined.