Question.

Does anyone have any references for Michel's Fixative or Fluid We use it for an immunofluorescence holding medium, but I don't have a reference on it for the manual ... (and I would like to read about it just for my own knowledge).

Answer.

Here's my procedure sheet for Michel's transport medium.

MICHEL'S TRANSPORT MEDIUM

Michel's transport medium (pronounced mee-SHELL) is used to transport specimens (such as renal biopsies and lymph nodes) for immunofluorescence studies. It is not a fixative, and is not suitable for any other use (particularly, it is not suitable for transporting living cells for flow cytometry). It should be stored refrigerated (not frozen) until use. Specimens may be kept in it at room temperature until they can be delivered to the reference laboratory. Zeus Medium, a commercial product, is probably similar.

    1.0 M potassium citrate buffer pH 7.0:
      dissolve 21.0 g citric acid monohydrate
      (or 19.2 g citric acid anhydrous)
      in 30 mL of hot deionized or distilled water. Cool.
      Adjust pH to 7.0 with 1 M potassium hydroxide (about 35 ml)
      Dilute to 100 mL with more water.

   Washing solution:

      25 mL 1.0 M potassium citrate buffer
      50 mL 0.1 M magnesium sulfate heptahydrate (F.W. 246.5)
      50 mL 0.1 M N-ethyl maleimide (= 12.5 g in 1 L of water)
                  (Sigma E3876.)
      Water to make 1 L
      Adjust to pH 7.0 with 1 M potassium hydroxide
      Store in refrigerator. (Cost about $50/25 g in 1994.)

   Transport medium:

      Dissolve 55 grams of ammonium sulfate in 100 mL washing solution. (Add slowly, with mechanical stirring.)
      Adjust pH to about 6.9 with 1 M potassium hydroxide (< 2 mL needed)

Specimens can be held at room temperature for five days in transport medium before processing. Specimens received in transport medium should be washed in three changes of washing solution, 10 minutes each wash.

Reference: Michel B. Milner Y. David K. Preservation of tissue-fixed immunoglobulins in skin biopsies of patients with lupus erythematosus and bullous diseases. A preliminary report. J. Invest. Dermatol. 59: 449-452 (1972).

This procedure received from J. Charles Jennette MD, Immunopathology Laboratory, North Carolina Memorial Hospital, Chapel Hill NC 27514

Bob Richmond
Samurai Pathologist
Knoxville TN
(RSRICHMOND[AT]aol.com)