PubMed · 823829
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S D Bulienko, P I Fogel, V V Tkachishin, K S Polomar'. 1976. [Chorionic antigens].. https://pubmed.ncbi.nlm.nih.gov/823829/
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The study of T cell responses in parasitic disease and allergy in humans has been limited by difficulties in the measurement of interleukin-4 (IL-4) in supernatants from antigen-stimulated peripheral blood mononuclear cells (PBMC). To obtain measurable amounts of IL-4 in vitro, we have added an amplification step to the antigen-specific response. Human PBMC were stimulated by tetanus toxoid (TT) or tuberculin (PPD) for 6 days and then pulsed with ionomycin and phorbol myristate acetate (PMA) for 24 h. TT-stimulated cells from nine revaccinated donors but not from seven unvaccinated donors and four that had only received childhood vaccinations against tetanus produced high levels of IL-4 (median (range) 1500 (300-3800), 316 (0-1600), and 270 (100-410) pg/ml, respectively, as measured by an enzyme linked immunosorbent assay, P = 0.005). PPD did not increase IL-4 production above the background level, although the majority of PPD-stimulated PBMC proliferated and produced interferon-gamma (IFN-gamma) in cultures without ionomycin and PMA. TT-induced IL-4 production correlated positively with proliferation. Culture supernatants did not interfere with IL-4 immunoreactivity and failed to affect ionomycin and PMA induced IL-4 production. The findings suggest that proliferating antigen-specific T cells were the source of IL-4 in these experiments. The method should prove useful for comparing the IL-4 producing ability of antigen-specific T cells from different individuals.
2-Dansylamino-2-deoxy-D-galactose (GalNDns) is a useful fluorescent probe to study the interaction of non-fluorescent sugars with the B4 lectin from Vicia villosa seeds (VVLB4). Binding of the lectin to GalNDns leads to a 5.2-fold increase in Dansyl fluorescence with a concomitant 10 nm blue shift in its emission maximum. The strong binding of GalNDns (Ka = 7.33 x 10(4) M-1 at 20 degrees C) is due to a favourable entropic contribution to the association process. Among the other sugars studied, GalNAc alpha 1-O-Ser followed by Me alpha GalNAc are the best ligands. 2-Deoxygalactose, galactosamine and galactose are 2013, 469 and 130 times weaker ligands, respectively, as compared to GalNAc, whereas GalNDns is about 2.44 times more potent than GalNAc, indicating that substitutions at the C-2 position of GalNAc have a considerable influence on the binding affinities. Equatorial orientation of the hydroxyl group at C-3 and axial orientation at C-4 as in galactose are important for the interaction with VVLB4. The C-6 hydroxyl group is not indispensable. The binding site of the lectin is directed exclusively towards monosaccharides alone. Interestingly enough, despite its preference for Me alpha GalNAc over Me beta GalNAc, in oligosaccharides, the lectin prefers terminal beta-linked GalNAc as compared to the alpha-linked one.