Leder Esterase
for mast cells


Pararosanilin 0.5 g
Distilled water 20 mL
Hydrochloric acid, conc 2.5 mL
Warm gently and filter.
Nitrosylated pararosanilin
Pararosanilin solution 0.1 mL
Sodium nitrite, 4% aqueous 0.1 mL
The sodium nitrite solution must be fresh.
After mixing, let stand for one minute.
Use immediately.
Sorenson Stock A
Disodium hydrogen phosphate 2.73 g
Distilled water 250 mL
Sorenson Stock B
Potassium dihydrogen phosphate 2.27 g
Distilled water 250 mL
Sorenson working buffer
Sorenson stock A 41 mL
Sorenson stock B 9 mL
Incubating medium
Naphthol-ASD chloroacetate 10 mg
N,N-dimethyformamide 1 mL
Sorenson's working buffer 35 mL
Nitrosylated pararosanilin 0.2 mL
Combine in the order given.
Mix well, filter and use immediately.
Light green
Light green SF yellowish 1 g
Distilled water 100 mL
Glacial acetic acid 1 mL

Tissue sample
4µ paraffin sections of formalin fixed tissue are suitable.


  1. Bring sections to distilled water.
  2. Place in the incubating medium for 40 minutes.
  3. Wash in running tap water for 5 minutes.
  4. Counterstain with light green for 30 seconds.
  5. Wash in running tap water for 5 min.
  6. Air dry.
  7. Clear in xylol and mount.

Expected results


  1. An alternative to air drying, which avoids some of the artifact introduced, is to blot the section, then wash with xylene. This is repeated until the sections are cleared.


Personal communication via Internet:–
Michael Konopka, Skin & Cancer Foundation, Australia
  Leder, L.D. (1964)
  Klinische Wochenschrift




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