The human hepatoma cell line HEP G2 was investigated in an indirect immunofluorescence study for localization of the sex hormone-binding globulin. Cells were grown directly to confluency on the slides used for the immunocytochemical staining. A fine granular cytoplasmatic fluorescence pattern revealed the presence of sex hormone-binding globulin. Chang-liver cells used as controls, incubated under the same conditions, did not fluoresce. The synthesis of the hormone\x=req-\ binding protein in HEP G2 cells, which could be stimulated by L-thyroxine in the culture medium, was monitored by either indirect immunofluorescence or by immunoradiometric determination of sex hormone-binding globulin in the supernatant. These studies demonstrate that immunofluorescence techniques are able to detect sex hormone-binding globulin in human hepatoma cells.Testosterone (T), 5cc-dihydrotestosterone (DHT) and estradiol-17ß (E2) are bound specifically to the sex hormone-binding globulin (SHBG) (1). One mole of steroid is bound per mole of protein (2); the affinity constants are relatively high to DHT and T, the binding of E2 to SHBG is weaker (3).The hormone-binding glycoprotein consists of two protomers with molecular weights of 53 and 46 kD and is nearly exclusively produced by the liver. The production is apparently regulated primarily by estrogens and androgens, estrogens having stimulating, androgens inhibiting effects (4). The stimulating influence of thyroid hormones is even stronger (5). Several other regulatory effects are known by clinical experiences: obesity and hyperprolactinemia decrease SHBG serum levels; cortisol, growth hormone and several synthetic andro¬ gens and gestagens also diminish hepatic produc¬ tion rates (6). On the other side, hepatic enzyme in¬ duction by several drugs like phenytoin increases circulating SHBG serum levels.In vitro experiments examining possible hor¬ monal modulations of SHBG in liver cells were en¬ abled by use of the human hepatoma cell line HEP G2 (5, 7). These cells secrete high levels of SHBG and the production can be influenced by several hormones in a physiological manner. Our main in¬ terest was to investigate the intracellular localiza¬ tion of SHBG in the HEP G2 cells and to see whether cytochemical methods would correspond to the findings of high amounts of this binding protein in the supernatant measured by radioimmunometric procedures. The indirect immunoflu¬ orescence findings obtained with HEP G2 have to be compared with those obtained with the human non-malignant liver cell line Chang-liver, which has no detectable SHBG production. Materials and MethodsFluorescence microscopy and photography were per¬ formed using an Olympus IMT-2 inverted research microscope and an Olympus OM-4 camera (Olympus

Bacterial neuraminidase plays an important role in the pathogenesis of some haemolytic anaemias. It divides neuraminic acid from the red cell surface to expose a hidden antigen (Thomsen-Friedenreich antigen, T). A physiologically circulating antibody can then react with the uncovered T and cause a rapid haemolysis. This study demonstrates the presence of T on human vascular endothelium. Similar to red cells it is exposed by the action of bacterial neuraminidase. The subsequent reaction with the physiological antibody could be involved in the pathogenesis of vascular damage observed in severe cases of bacterial septicaemia.

A newly developed ion exchange chromatography is reported; it is a simple and quick method to separate a highly purified IgM fraction from blood serum. The immunofluorescence test was used to demonstrate that these fractions contain only virus-specific IgM antibodies, but no demonstrable IgG antibodies, which can often block the specific IgM reactivity by competitive inhibition. The specificity of the reaction was tested on sera from 145 persons: the IgM test was always positive in clinically proven viral infections; the reaction was negative in all patients whose infection had occurred some time in the past. A series of suspected virus infections could be verified by the demonstration of specific IgM antibodies.