PB1883 GLYCOPROTEIN STRUCTURES OF LEUKEMIC B‐LYMPHOCYTES AND CD38 EXPRESSION IN CHRONIC LYMPHOCYTIC LEUKEMIA

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Background: Glycoprotein cell structures (glycocode) play an important part in intercellular interaction. Changes in their structure may determine the ability of leukemic cells to spread (expansion), and impact the exposure of membrane antigen, which transmit pro‐ and antiapoptotic signals. Aims: The aim of this study was to conduct research of leukemic lymphocytes glycocode in chronic lymphocytic leukemia (CLL) and its interconnection with the expression of prognostically significant CD38 antigen. Methods: Carbohydrate determinants of leukemic lymphocyte membrane were studied in 65 CLL patients using panel of 12 lectins with main carbohydrate specificity, and CD38 expression. Results: 27% of lymphocytes of CLL patients were identified as containing Thomsen–Friedenreich antigen (PNA+), absent in normal lymphocytes. Leukemic lymphocytes are characterized by a significantly lower level of I and II type N‐glycans’ glycosidic chains (RCA). The lymphocytes of the CLL patients reacted weaker with GalNAca‐specific SBA lectin, Mana‐specific PSL lectin and GlcNAcb‐specific lectins (WGA і STL), polyspecific lectin PHA. We researched the correlation between lectin receptors expression level and CD38 antigen. The patients were divided into groups with low and increased antigen expression level. In the low CD38 expression level group (≤30%) no statistically significant changes in interaction with lectins were detected as compared to the general patients group. Leukemic lymphocytes with increased CD 38 expression (>30% CD38+ cells) exhibit a significantly higher interaction level with PNA lectin (T antigen) and decreased interaction level with RCA; they have more terminal Fucα residues (H antigen, LAL lectin). A correlation analysis has been done between the percentage of leukemic cells that bind lectins and the number of CD38+ lymphocytes. A high level of CD38 expression correlates with increased A antigen disaccharide content (GalNAAcα1→3Galβ; SBA lectin), decrease of GlcNAcβ sialylated residues (WGA lectin, r = –0,702; STL lectin, r = –0,503), and sialic acid (SNL lectin). They have less polyantennae N‐glycans (PHA lectin, r = –0,701). Summary/Conclusion: A higher CD 38 expression level is accompanied with an increased number of cells containing Thomsen‐Friedenreich antigen (PNA lectin) and corelates positively with antigen A level (SBA lectin) and terminal Fucα (LAL lectin) and a decreased level of Galβ glycosidic residues (RCA lectin); it correlates negatively with a decrease of GlcNAcβ sialylated residues (WGA, STL lectin), and residues of neuraminic acid (NANA, SNL lectin) and polyantennae N‐glycans (PHA‐L lectin).

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