IN-SITU END LABELING - EFFECT OF PROTEOLYTIC-ENZYME PRETREATMENT AND HYDROCHLORIC-ACID

Aim-To determine the effect of dilute hydrochloric acid on the in situ end labelling (ISEL) reaction, with and without a variety of differen t proteolytic enzymes. Methods-Sections of tissue fixed in buffered fo rmalin were pretreated with trypsin, protease XIV (at two different co ncentrations), or protease XXIV (for two different incubation times), with and without subsequent 1 M hydrochloric acid treatment. The resul ts were compared with those obtained using hydrochloric acid alone, wi th proteinase K, and pepsin pretreatment, and with no pretreatment. Re sults-When hydrochloric acid was added to the sections in addition to trypsin, protease XIV: there was a significant increase in ISEL reacti vity in both apoptotic nuclei and morphologically normal nuclei. Hydro chloric acid alone had no significant effect. Conclusion-Hydrochloric acid has a distinctive effect on the ISEL reaction that is dependent o n prior proteolytic digestion.