Purine nucleoside phosphorylase(PNP)細胞化学的染色法の検討(第二報) ヒト末梢リンパsubpopulation での陽性率と enzymemarker としての可能性

抄録

Purine nucleoside phosphorylase(PNP), the enzyme in the purine salvage pathway, is necessary for the normal human T cell function of the immunological system, since PNP deficiency is associated with severely defective T cell immunity but with normal B cell immunity. Therefore, PNP is speculated to be useful as an enzyme marker for the differentiation and maturation of T cells. In order to test this possibility, the PNP activity in T, B and null cells from healthy subjects and patients with lymphoproliferative disorders has been investigated by using a new technique developed for the enzyme cytochemical staining.
In this method, a suspension of unfixed-lymphocytes in phosphatebuffered saline is mixed on a glass slide directly with agarose sol containing the reagents for detection of the PNP activity. The mixture solidifies, is incubated and then dried in the form of a thin layer on the slide for a light-microscopic observation. The normal morphological shape was clearly retained in more than 90% of observed cells. The cytochemical reaction is based on the method reported by Kishi (Bull. Tokyo Med. Dent. Univ.16: 289,1969). Results of negative controls without the substrate, inorganic phosphate or xanthine oxidase provide evidence for staining dependent on the PNP activity.
In healthy adults, the mean percentages of PNP-positive cells were 95% (n=7),92% (n=6) and 91% (n=3) in unseparated lymphocytes, EACrosette forming cells and E-rosette forming cells, respectively. These considerably high percentages of PNP-positive cells indicate that PNP activity is present not only in T cells but also in B cells. Contrary to the data, more than ninety six percent of the lymphocytes in 2 of 5 patients with B cell chronic lymphocytic leukemia (CLL) was PNP-negative. A slight decrease of the activity was found in the lymphocytes of the other CLL patients. The lymphocytes of a patient with null cell acute lymphocytic leukemia showed greatly decreased PNP activity. These results suggest that PNP activity is expected to be a possible enzyme marker to differentiate tumor cells or immature lymphocytes from matured cells.