[Alkaline phosphatase in human lymphocytes. II. A method for ultracytochemical detection of alkaline phosphatase in lymphocytes].

For the ultracytochemical identification of alkaline phosphatase in lymphocytes gained from the peripheral blood of healthy individuals a sensitive method is described which allows the low enzyme activity of these cells to be determined. This was possible because the authors succeeded in stabilizing lead ions in the alkaline medium by forming a complex directly between tris-(hydroxymethyl) aminomethan and lead (II) citrate. AP localized ultrachemically in lymphocytes in particular formations similar to phosphasomes of neutrophilic granulocytes. In those lymphocytes stimulated by lipopolysaccharides a high enzyme activity could be observed and, in addition to phosphasomes, the product of response can also be found in canal-like structures of the endoplasmatic reticulum. These findings contribute to clarify the ultrastructural localization of alkaline phosphatase in lymphocytes and may be regarded as an aid in discovering the importance of the enzyme in the biology of lymphocytes or in its activation, respectively.