The sulfation of the adrenal steroid dehydroepiandrosterone (DHEA) is a critical step in the provision of substrates for estrogen biosynthesis by the placenta during pregnancy. This enzyme reaction is catalyzed by a cytosolic sulfotransferase (ST) found in many key body tissues, and we have examined the ontogeny and localization of expression of this important enzyme in three tissues: the liver, adrenal, and kidney. Hepatic DHEA ST expression increased with advancing gestational age before reaching near-adult levels in the early postnatal period, suggesting an increased requirement for this enzyme in the liver as development progresses, whereas in the adrenal and kidney there was no obvious ontogenic pattern. The enzyme was expressed at a 5-fold higher level in the adrenal than in the liver and some 40-fold higher than in the kidney. Comparison of enzyme activity measurements and quantitation of the expression of DHEA ST by immunodot blot analysis with an anti-DHEA ST antibody preparation demonstrated the fragility of the enzyme activity and suggested that immunoquantitation was a superior method for assessment of levels of expression of this enzyme in widely different tissue sources. Examination of the localization of DHEA ST in these tissues by immunohistochemistry showed that in liver, DHEA ST was expressed in embryonic hepatocytes and continued to be expressed in these cells into adulthood, when there was some concentration of immunostaining around central veins. In the fetus, the adrenal enzyme was expressed in the fetal zone, whereas in adult tissue, staining was localized principally to the zona reticularis. Renal DHEA ST was present in the proximal and distal tubules, loops of Henle, collecting ducts, and their progenitors, but was at no time expressed in the vascular glomerulus. In light of the broad substrate specificity of this enzyme toward other steroids, in particular bile acids and cholesterol, the information presented forms a strong basis for further studies into the role of DHEA ST in modulating the activity of a number of biologically active and potentially toxic steroids in the developing human.

The objective of our study was to determine the cellular localisation of glucose-6-phosphatase in developing human kidney using monospecific antiserum and a standard immunohistochemical method (peroxidase-antiperoxidase, PAP) on formalin fixed and paraffin embedded tissue. In embryonic and early fetal development of the metanephric kidney, glucose-6-phosphatase is located primarily in derivatives of the ureteric bud such as the pelvis, calyces and collecting ducts. In mid-fetal life as nephrons evolve and develop they become increasingly immunoreactive to glucose-6-phosphatase, such that in mature metanephric kidney the proximal tubules are highly reactive for glucose-6-phosphatase with other elements of the nephron also immunopositive albeit at lower reactivities. In addition the parietal layer of Bowman's capsule and some cells of the visceral layer are immunopositive. Only with the development of nephrons does the early predominance of glucose-6-phosphatase immunoreactivity to ureteric bud derivatives change: in mature kidney the reactivity in the collecting ducts is a small proportion of the total. In proximal tubular cells the distribution of glucose-6-phosphatase immunoreactivity is relatively uniform throughout development in contrast to collecting ducts where in fetal life this reactivity is displaced to the apices and basal areas by intracellular glycogen deposits. The mesonephric kidney has a similar pattern of glucose-6-phosphatase immunoreactivity to that of metanephric kidney. The availability of monospecific antiserum to glucose-6-phosphatase and immunohistochemical methods now allows an alternative approach to cellular localisation. Many of the difficulties in the fixation of tissue and assay of glucose-6-phosphatase activity inherent in conventional histochemical methods are avoided by such methods.

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Circulating immune markers sICAM-1, sELAM-1, sMHC-I, beta 2-MG, sCD4 and sCD8 were evaluated prior to and during immunotherapy with biologically active doses of interferon gamma (IFN-gamma) in 16 patients with advanced renal cell carcinoma (RCC) over a period of 12 months. Compared to 20 healthy controls, significantly (P < 0.01) elevated baseline levels of circulating adhesion molecules sICAM-1 (mean 1166 vs 230 ng/ml) and sELAM-1 (70 vs 17 ng/ml) were found in all patients. Compared to responders (n = 2) or patients with stable disease (n = 2), progressive disease during therapy (n = 12) was associated with significantly (P < 0.05) higher mean concentrations of sICAM-1 (1574 vs 962 ng/ml) and sELAM-1 (86 vs 46 ng/ml). Pretherapeutic and intratherapeutic levels of sMHC-I among the RCC patients were significantly (P < 0.05) lower than among the controls (0.41 vs 0.8 ng/ml). sCD4 levels clearly showed the same tendency (24 vs 33 U/l). sCD8 baseline levels, by contrast, were significantly (P < 0.05) elevated (564 vs 336 U/l), reflecting either activation of the NK-cell subset or increased synthesis of CD8+ T-suppressor cells. Again, significantly (P < 0.05) higher intratherapeutic sCD8 concentrations were observable with progressive disease than with response to therapy or stable disease (721 vs 355 U/l). Interestingly, although the biologically active dose of IFN-gamma was defined by an increase in beta 2-MG release of at least 30% within 48 h after injection, none of the other markers showed any significant alteration following IFN-gamma administration, suggesting that IFN-gamma in vivo does not produce changes in circulating markers of activation that might be expected on the basis of its effects in vitro. The finding of significantly elevated concentrations of sICAM-1, sELAM-1 and sCD8 in the presence of low sCD4 and sMHC-I levels might be of clinical significance for indicating ongoing tumor progression.

PGE2 and PGF2 alpha are released into the media of human fetal lung organ cultures in decreasing amounts with time. This decline in PGs is not due to culture failure or loss of synthetic capacity, which can be stimulated by fetal bovine serum, nor is it due to increased catabolism of PGE2 to 13,14-dihydro-15-keto-PGE2 (PGEM) or of PGF2 alpha to 13,14-dihydro-15-keto-PGF2 alpha (PGFM). Immunohistochemically reactive PGs are not retained within lung cells. Antisera against methyl-moximated derivatives of PGEM or PGFM and preceded by derivatization on tissue sections of PGs by methyl-moximation not only demonstrate the localization of PGEM and PGFM in epithelial cells and blood vessels, but also show an overall decline in immunoreactivity with time. In addition electron microscopy of uncultured fetal lung removed directly after termination reveals various degrees of mitochondrial damage and in some cases plasma membrane blebs which resolve during the period in culture and as fetal lung self-differentiates. It is proposed that oxidative and mechanical stresses, occurring during termination of pregnancy or tissue preparation, result in cell damage and increased lung prostaglandin production, which, although decreasing during culture as cells recover, is sufficient to trigger terminal self-differentiation.

Human fetal lung at 16-19 weeks gestation has a partially differentiated epithelium, and in organ culture, distal airsacs dilate and the epithelium autodifferentiates to type I and II pneumatocytes, processes regulated by endogenous prostaglandin PGE2. Human fetal trachea, at the same gestation, has a terminally differentiated mucociliary epithelium but after 4-6 d in organ culture, develops squamous metaplasia. Tracheal cultures restricted to 3 d have normal phase-contrast and light microscopy appearances and immunohistochemical reactivities (epithelium: cytokeratin 7,8,18; glutathione S-transferase pi-isozyme; epithelial membrane antigen and mesenchyme; desmin; vimentin). In human fetal trachea organ cultures, the predominant prostaglandins released are 6-keto-PGF1 alpha, PGF2 alpha, and PGE2, a pattern similar to that previously described for human adult trachea and lung. In fetal lung cultures, 13,14-dihydro-15-keto-PGF2 alpha is the major prostaglandin released with lesser amounts of 13,14-dihydro-15-keto-PFG2 alpha,PGF2 alpha,PGE2, and 6-keto-PGF1 alpha. Human fetal lung in vitro has the competence to self-differentiate, as early as 12 weeks gestation and presence of high levels in fetal lung of the inactive metabolite 13,14-dihydro-15-keto-PGE2 relative to PGE2 suggests that active prostaglandin catabolism may be one of the mechanisms to retard this stage of maturation in vivo by limiting PGE2 availability. Surprisingly, the profile of prostaglandins released from fetal lung organ culture does not change to that of a mature lung with terminal differentiation of the epithelium, and this may indicate differences in the expression of key prostaglandin-metabolizing enzymes in developing human fetal lung in culture and with in utero ontogeny.