Differences between tumor clones of B lymphocytes with restriction of kappa or lambda immunoglobulin light chains in patients with chronic lymphocytic leukemia.
Authors: Selyutina Olesya N. , Guskova Nailya K. , Lysenko Irina B. , Nikolaeva Nadezhda V. , Kapuza Elena A. , Pushkareva Tatiana F. , Tishina Anna V. , Lisunova Zinaida P. , Tselishcheva Irina V. , Golomeeva Nadezhda V. , Nozdricheva Anastasia S. , Guskova Ekaterina A. , Gusareva Marina A. , Donskaya Aliya K. , Samaneva Natalia Yu. , Kamaeva Inna A. , Krokhmal Yulia N. , Belgova Svetlana V. , Morozova Antonina A. , Zakharchenko Viktoria R. 
Published: June 2022

e19520

Background: The purpose of this study was to compare morphological and immunophenotypic characteristics of the tumor population of B-lymphocytes with varying restrictions of immunoglobulin light chains in patients with chronic lymphocytic leukemia (CLL). Methods: We examined 30 patients with CLL (median age 64.9±8.6 years). All patients underwent CBC+DIFF blood tests (Sysmex XE 2100, Japan), morphological examinations (BioVision; Micros, Austria), and immunophenotyping (IPT) by multicolor flow cytometry (Navios 10/3, Beckman Coulter, USA) of the bone marrow and venous blood. According to the IPT results, the patients were divided into: group 1 - 22 patients (73.3%) with tumor cells expressing kappa immunoglobulin light chains, and group 2 - 8 patients (26.7%) with lambda immunoglobulin light chains. Statistical processing of results was performed in the STATISTICA 13.0 program. Results: Morphological tests revealed differences between tumor populations of B lymphocytes. In group 1, the tumor population was represented by small cells of the same type with scanty, often unvisible cytoplasm and nuclei with a lumpy chromatin structure, without distinct nucleoli. In group 2, the sizes of cells varied from small to large, with abundant cytoplasm, round or folded nuclei, smoothed chromatin structure and 1-2 nucleoli. Prolymphocytes were observed among tumor cells (8.1±1.7% of WBC). IPT also revealed differences in tumor clones: morphological uniformity of tumor cells in group 1 was observed in the distribution of tumor cells reflected in low parameters of light scattering on the diagram: location to the left along the FSC axis - from 200 to 400 units and below along the SSC axis - from 10 to 160 units. In group 2, the lymphoid zone was heterogeneous and stretched on the plot: location to the right along the FSC axis - from 200 to 1000 units and higher along the SSC axis - from 10 to 400 units, closer to the monocyte zone, which indicated morphological polymorphism of tumor cells. The expression of CD45 also differed: in group 1, the expression was higher and tumor B lymphocytes were higher by fluorescence intensity on a dot plot on the CD45 / SSC scale in the second half of the third decade and in the fourth decade - to the right compared with group 2, where aberrant B lymphocytes were in the third decade and more to the left. The CD45 expression allowed defining differentiation of the tumor clone: the population in group 1 was represented by mature cells, and in group 2 by less mature and/or intermediate forms. There were no significant differences in the expression of other markers. The revealed differences were typical of both the peripheral blood and bone marrow. Conclusions: The study established morphological and immunophenotypic differences between tumor clones of B lymphocytes expressing either kappa or lambda immunoglobulin light chains in patients with CLL.