Modulation of Leydig cell testosterone production by secretory products of macrophages.

Unstimulated macrophages from testes inhibited the production of testosterone by Leydig cells from adult, but not immature, Sprague-Dawley rats (significant after 48 h). Similar results were observed with unstimulated macrophage-conditioned media, suggesting that the observed effect was mediated by one or more secretory products. None of these substances was interleukin-1, since macrophage supernatants tested negative in an interleukin-1 alpha and interleukin-1 beta sensitive, thymocyte assay.

IL-1 receptor antagonist in saliva; characterization in normal saliva and reduced concentration in Sjögren's syndrome (SS).

The characterization of a salivary factor cross-reacting with IL-1 receptor antagonist (IL-1Ra) is described. The apparent molecular weights of two species were 23 kD, consistent with the secreted peptide (sIL-1Ra), and 20 kD, consistent with the intracellular peptide (icIL-1Ra). It had an inhibitory activity on IL-1-stimulated fibroblasts, which is characteristic of IL-1Ra.

Discrepancy between 3H-thymidine uptake and cell cycle studies in stimulated lymphocyte cultures treated with methotrexate.

The mode of action of methotrexate (MTX) in rheumatoid arthritis (RA) is unknown. The hypothesis that its cytostatic effect may be involved has been questioned based on the evidence of several negative results, the most intriguing being its lack of effect on the Lymphoblastic Transformation Test (LTT) and other lymphoproliferations in cultures from patients' samples. Our study demonstrates that LTT evaluation by 3H-thymidine uptake, a standard method, is misleading when applied to MTX-treated cells.

Ultrastructural and immunohistochemical evidence of in situ differentiation of mononuclear phagocyte system cells in the interstitium of human fetal testis.

Ultrastructural and immunohistochemical studies were made of the testicular interstitial tissue from eight human fetuses of 15 to 27 weeks gestation. Three cell types developed in mesenchymal cells: Leydig cells and peritubular cells, as already reported, and cells of the mononuclear phagocyte system (MPS), which are located in the intermediate area of the interstitial tissue. Located at the periphery of Leydig cells, these gradually differentiate between 16 and 20 weeks and later acquire the ultrastructural characteristic of histiocytes during the involution phase of the fetal testis.