Characterization and Comparison of Human LAD1 Mast Cells with Human LAD2 Mast Cells

LAD2 human mast cells were developed over 15 years ago and have been distributed worldwide for studying proliferation, receptor expression, mediator release/inhibition and signaling. LAD2 cells were derived from CD34+ cells following marrow aspiration of a patient with aggressive mastocytosis. Another aspiration gave rise to the cell line LAD1 which has been under liquid N2 and not distributed due to the availability of LAD2. LAD1 cells were recently thawed for study. We queried whether LAD1 had unique properties for the study of human mast cell biology LAD1 and LAD2 cells were cultured under identical conditions. Experiments examined proliferation, beta-hexosaminidase (beta-hex) release, surface receptor and granular protease expression, gene expression and infectivity with HIV. LAD1 cells were larger and more granulated as seen with Wright-Giemsa staining and FSC/SS expression, with cell numbers doubling in 4 wks, in contrast to LAD2 cells which doubled every 2 wks. Both LAD1 and LAD2 cells released beta-hex to an IgE-mediated stimulus. LAD1 cells showed log-fold increases in FcepsilonRI/CD117 and expressed CD133/CCR3(CD193)/ CCR5(CD195)/CXCR4(CD184) and IL3R(CD123). LAD2 expressed CD133/CD193 but not CD195/CD184 or CD123. LAD1 tryptase expression was one log fold increased. Both cell lines could be infected with HIV. Expression arrays revealed differences in gene expression. LAD1 cells when compared to LAD2 cells have a slower proliferation rate, are larger and more granulated, have increased FepsilonRI/CD117 and tryptase expression and different gene expression. Thus, while LAD1 and LAD2 cells share many characteristics, in some situations, one cell line may have an advantage over the other.