Improved detection of terminal transferase (TdT): the use of detergents on glutaraldehyde-fixed non-dehydrated cells prevents denaturation and diffusion artifacts.

TdT as an intranuclear enzyme mainly of immature lymphoid cells is commonly determined immunologically using air-dried cell smears fixed with methanol. Both cell dehydration and alcohol fixation were found here to denature TdT and surface antigens. This could be prevented by using non-dehydrated cells bound electrostatically to poly-L-lysine-coated slides, fixed minimally with glutaraldehyde and rendered permeable to antibodies by the non-ionic detergent Brij 56. Crosslinking glutaraldehyde in addition prevented diffusion of TdT to extranuclear sites. By avoiding artifacts of denaturation and diffusion, a higher sensitivity in the detection of TdT was achieved despite considerably lower quantities of antibody.