Inhibitory effect of galanin on growth hormone release from rat pituitary tumor cells (GH1) in culture.

The growth hormone (GH) releasing effect of GH-releasing hormone (GHRH) and galanin, a 29-amino acid peptide widely distributed in mammalian CNS, was investigated in cultured rat pituitary tumor cells (GH1) as compared to normal rat somatotrophs. GHRH stimulated dose-dependently GH secretion in normal somatotrophs but did not affect GH secretion in GH1 cells. Galanin (1-10 microM) stimulated GH release in a concentration-dependent manner, but with lower potency as compared to GHRH, in normal rat pituitaries but was inhibitory in rat GH1 cells. The results of this study indicate that while galanin has the ability to stimulate GH release from dispersed pituitary cells of normal rats it has potent direct inhibitory effects on GH release from tumor rat cells.

The crystal structure of 6I-(6-aminohexyl)amino-6I-deoxycyclomaltoheptaose.

The monosubstituted cyclomaltoheptaose derivative, 6I-(6-aminohexyl)amino-6I-deoxycyclomaltoheptaose, crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 32.513(2), b = 15.3871(9), c = 15.2645(9) A, V = 7636.6(8) A3 and Z = 4. The macrocycles are spirally aligned along the twofold screw axis parallel to the c crystal axis forming polymeric-like columns. The 6-aminohexyl chain enters the cavity of an adjacent cyclomaltoheptaose moiety in the column from the secondary side and its extremity protrudes from the primary side of the latter. All the atoms of the chain exhibit high thermal motion.

Flow cytometric indirect immunofluorescence assay with high sensitivity and specificity for the detection of antibodies to HSV-1 and HSV-2.

Cells infected with HSV-1 or HSV-2 develop viral antigens which can be detected by immunofluorescence. We developed a flow cytometric indirect immunofluorescence assay to detect and quantitate antibodies to HSV-1 and HSV-2 in human sera. Results obtained by flow cytometry for detecting antibodies against HSV-1, when compared with results obtained by ELISA, showed an index of overall agreement of 100%. The correlation between the antibody titers obtained with each method was found to be highly significant. An index of overall agreement equal to 94.1% was observed between results obtained by flow cytometry and by immunofluorescence as concerns the discrimination of HSV-2 positive from negative samples. However, the correlation between antibody titers was found to be not statistically significant. The flow cytometric assay proved to be type-specific.

A monoclonal antibody to the NH2-terminal segment of human IFN-gamma selectively interferes with the antiproliferative activity of the lymphokine.

To gain more information about the relationship between the structure of IFN-gamma and its activity, a peptide corresponding to a hydrophilic peak between amino acids 4 and 16 was used to immunize mice and generate mAb. mAb IGMB-15 reacts to both native and rIFN-gamma and neutralizes the antiproliferative activity of IFN-gamma without affecting its antiviral activity or its ability to up-regulate HLA-DR Ag expression. Moreover, we observed that mAb IGMB-15 was unable to inhibit the binding of radiolabeled IFN-gamma to its cellular receptor. These findings show that the NH2-terminal region may somehow be involved in the biologic activity of IFN-gamma. Besides, the capability of mAb IGMB-15 to inhibit the antiproliferative but not the antiviral activity of IFN-gamma in the same cell (HEp-2) suggests the presence of different elements involved in signal transduction, which may account for the multiple activities of the lymphokine.

High-titre antibodies to a foreign epitope elicited by affinity-purified hybrid LamB proteins.

A monoclonal antibody to the LamB protein, named LBS-1, was developed and characterized. It was then covalently bound to Sepharose and used to purify hybrid LamB proteins from Escherichia coli crude extracts. A peptide of the interferon-gamma (IFN-gamma) NH2-terminal region, inserted within the LamB protein, was used as a model to assess immune response in mice injected with sonicated E. coli extract or with affinity-purified hybrid LamB protein. None of the mice immunized with the whole bacterial extract produced antibodies to IFN-gamma. On the other hand, all the mice immunized with the purified protein developed high-titre anti-IFN-gamma antibodies. These results might be due to the presence of bacterial components capable of masking the LamB protein to the immune system. The use of affinity-purified LamB proteins may constitute in some instances a more effective way of generating an immune response against foreign epitopes as opposed to whole bacterial antigens.

Natural antibodies to IFN-gamma in man and their increase during viral infection.

Natural antibodies to IFN-gamma were found in healthy individuals ranging from newborn babies to adults and, at higher levels, in patients suffering from different viral infections. During a viral infection, the titer of anti-IFN-gamma antibodies was observed to be correlated with the stage of the disease. Antibodies specific to IFN-gamma were affinity purified both from sera taken from healthy individuals and sera from viral-infected patients, by using a rIFN-gamma-coupled CNBr-activated Sepharose 4B column. The antibodies were found to be of the IgG class, and maintained their ability to bind rIFN-gamma. They were then tested for neutralizing activity and none of the IgG preparations we analyzed impaired the antiviral activity of rIFN-gamma. This finding suggests that the antigenic determinants recognized by these antibodies on the IFN-gamma molecule are located outside the site, on the IFN-gamma molecule, responsible for its antiviral activity.