Lactate Dehydrogenase Isoenzyme Pattern as a Marker Of Lymphocyte Populations in the Axolotl (Ambystoma Mexicanum)

Abstract

The present study investigates the different LDH isoenzyme patterns of Axolotl lymphocytes in terms of their thymic, splenic and blood origin, and the LDH pattern of erythrocytes. The total LDH expression observed in lymphocytes as well as in erythrocytes is represented by six isoenzymes with different activities according to the cell origins. Predominant LDH5 and LDH6 can be noticed in every lymphocyte population while LDH1 and LDH2 are dominant in erythrocytes. Thymocytes are characterized by a moderate and nearly equivalent activity of LDH6 to LDH2 isoenzymes and by a weak LDH1 activity. In both peripheral blood and spleen lymphocytes the LDH6, LDH5, LDH2 and LDH1 activities are higher than in thymocytes. LDH6 and LDH5 are strongly dominant, but LDH5 activity is always weaker tfian LDH6 activity. LDH4 and LDH3 are less expressed in blood and spleen lymphocytes than in thymocytes. The different subpopulations of thymocytes and splenic lymphocytes separated by density on a discontinuous Ficoll gradient, express the same LDH zymograms as the whole unseparated thymic or splenic population. Nevertheless, the expression of the total LDH activity varies with each subpopulation and is always lower than the total LDH activity of an unfractionated population. The study of the kinetic effect of hydrocortisone on the amplitude of the global LDH expression of thymic and splenic lymphocytes, shows that after 14 days, hydrocortisone treatment shuts down the LDH expression of thymocytes, but does not alter the LDH expression of splenic lymphocytes. The use of LDH as a tool for T and B-like lymphocyte markers in amphibians is discussed.