Medizinische Universität Graz - Research portal
Selected Publication:
HUBER, LA; BOCK, G; JÜRGENS, G; TRAILL, KN; SCHONITZER, D; WICK, G.
INCREASED EXPRESSION OF HIGH-AFFINITY LOW-DENSITY-LIPOPROTEIN RECEPTORS ON HUMAN T-BLASTS
INT ARCH ALLERGY APPL IMMUNOL 1990 93: 205-211.
Doi: 10.1159/000235302
Web of Science
FullText
FullText_MUG
Google Scholar
- Co-authors Med Uni Graz
- Jürgens Günther
- Altmetrics:
- Dimensions Citations:
- Plum Analytics:
- Scite (citation analytics):
- Abstract:
- Like all cells, lymphocytes need cholesterol for proper function, a requirement met by a finely tuned homeostasis between intracellular synthesis and uptake from the environment via low-density lipoproteins (LDL). We used flow cytometry to analyze the receptor activity of resting cells and T blasts incubated/activated in serum-free culture medium, or in medium supplemented with 25-5,000-mu-g/ml LDL. Dioctadecyl-indocarbocyanine has proved to be a useful fluorescent probe for investigating the LDL receptor activity of lymphocytes. The results show the receptor activity of day-3 resting T cells to be reduced more than 50% by 50-mu-g LDL/ml, whereas 100-fold higher concentrations are necessary to achieve the same level of reduction in day-3 PHA blasts. The LDL receptor activities of individual blood donors' resting T cells, in vitro cholesterol-deprived resting T cells, and activated T blasts, were compared using two analytical techniques: spectrofluorometric analysis of detergent-solubilized cell suspensions and flow cytometric analysis of single living cells. Receptor affinity was determined by Scatchard analysis of spectrofluorometric binding curves, and by Line-weaver-Burke plots of flow cytometric data. Both methods yielded essentially identical dissociation constants (K(d)) for cholesterol-deprived resting T cells and mitogen-activated T blasts, which fell in the expected range for the high-affinity LDL receptor (4.1-8.9 nM). In addition, spectrofluorometric analysis, but not flow cytometry, permitted quantification of LDL uptake. The low receptor activity of freshly isolated T cells, however, could only be reliably measured by flow cytometry; this highly sensitive technique not only afforded specific binding curves, but also determination of K(d) of the same high affinity (7.5 nM) as that of T cells with upregulated LDL receptor activity.