17β-Hydroxysteroid oxidoreductases of human fetal and adult tissues: Immunological cross-reactivity with an anti-human placental cytosolic 17β-hydroxysteroid oxidoreductase antibody

To determine whether the immunological determinants of human placental 17β-hydroxysteroid oxidoreductase (17β-HSOR) were present in 17β-HSORs of tissues of the human fetus and adult and of various non-human cells maintained in culture, western immunoblot analysis was conducted by use of a polyclonal antibody directed against determinants of the placental cytosolic enzyme. Tissues and cells were evaluated for the presence of immunocross-reactive proteins with a relative molecular mass (M_r) similar to that of placental 17β-HSOR (∼ 34 000). By use of homogenates of human fetal tissues, immunostaining of 17β-HSORs of M_r∼34 kDa was detected in trophoblast, fetal adrenal neocortex, fetal zone of the adrenal gland, liver, intestine, kidney, brain, lung, skin, heart, spleen, pancreas, chorion laeve, and, occasionally, amnion. Immunostaining at M_r∼34 kDa also was demonstrated by use of cytosolic preparations of fetal tissues and, in some cases, by use of unwashed microsomal fractions; this protein was either absent or present in almost undetectable amounts in washed microsomes, except for placenta and fetal brain. Immunostaining at ∼34 kDa was demonstrated occasionally in decidua of pregnant women by use of homogenates, but was not detected in endometrium or myometrium of non-pregnant women, testis of an adult man, mouse and rat Leydig tumour cells, mouse and rat adrenal tumour cells, and normal bovine adrenocortical cells.