Influence of fixatives and embedding media on immunolabelling of freeze-substituted cells.

Fixatives and embedding media are known to alter antigen epitopes and reduce antibody recognition unpredictably. Every antigen-antibody interaction may be influenced differently. In this study we concentrate on the influence of fixatives, commonly used in immuno-electron microscopy, the dehydration process, and the embedding media Lowicryl HM20 and K4M. The results obtained with our model system show that: the lesser chemical fixation, the more intense the labelling, and that dehydration by freeze-substitution preserves the antigenicity better than dehydration by progressive lowering of temperature, PLT, and finally that there is no obvious difference in labelling between the apolar Lowicryl HM20 and the polar Lowicryl K4M.