[Modification of splenic 5'-nucleotidase activity during proliferative processes in the spleen. Histoenzymatic study in the rat].

In the rat spleen, periarteriolar lymphocyte sheath and the external area of the germinal center in the white pulp and the Billroth's cords in the red pulp possess a strong 5'Nucleotidase activity. During antigenic stimulation a lymphocyte proliferation occurs in the white pulp, while 5'Nucleotidase activity is weak. In the germinal center there is inverse relationship between development of the mitotic internal area and the 5'Nucleotidase external zone. Likewise in the myeloid metaplasia of the red pulp induced by fibrosarcoma development, the 5'Nucleotidase of the Billroth's cords is decreased. 5'Nucleotidase might exert a negative control on cell proliferation probably through adenosine production. On the other hand this enzymatic activity might gave back available nucleosides for cellular proliferation, lymphocytes being especially impermeable to nucleotides.