IDENTIFICATION OF RENIN-CONTAINING CELLS IN THE CHORIODECIDUA

Chorionic trophoblast, decidual cells, and macrophages have all been named as the sire of renin in the Placental membranes. To establish more clearly the nature of the renin-containing cells in the placental membranes, double immunostaining techniques were used to stain renin and specific cell markers in the same tissue sections. Cytokeratin was selected as an ectodermal cell marker and CD68 as a cytoplasmic macrophage marker. Cross-binding between antibodies was prevented by blocking species-related binding sires between the first and second sequence of the double-immunostaining procedures and by using highly selective immunostaining techniques in the second sequence. The results clearly shall, renin immunostaining in CD68-positive macrophages and not in cytokeratin-positive trophoblast. The anti-renal renin monoclonal antibody showed high affinity cross-reactivity with cathepsin D, another aspartic proteinase that can release angiotensin I from angiotensinogen. This should be seen in the context of earlier findings that only two of four anti-renal renln monoclonal antibodies showed staining tn uterine and Placental tissues and both cross-reacted with cathepsin D. The results indicate that differentiation between renin and cathepsin D and possibly, other substances with shared properties and epitope homology deserves more attention than it has received thus far.