Changes in fluorescence polarization of a membrane probe during lymphocyte-target cell interaction
Berke, G.; Tzur, R.; Inbar, M.
Journal of Immunology 120(4): 1378-1384
1978
ISSN/ISBN: 0022-1767 PMID: 641353 Document Number: 129754
Interaction of exposed membrane-lipid regions after mixing of immune cells (TC) was studied by monitoring the degree of fluorescence polarization (P) of 1,6-diphenyl 1,3,5-hexatriene (DPH), a lipophilic probe, which can be transferred upon contact of lipid phases. Since the P of DPH-labeled PEL and labeled TC differed significantly, detection of DPH translocation between labeled and nonlabeled cells was possible. A decrease in P was observed after interaction of DPH-labeled PEL and nonlabeled TC. An increase in P was detected after nonlabeled PEL were allowed to react with DPH-labeled TC. These changes in P were evident when TC were reacted with specific PEL. Substantial changes were also monitored with PEL immunized against 3rd-party target cells. No significant changes in P were obtained when DPH-labeled TC were reacted with normal or immune lymph node cells or thymocytes, or with anti-TC antibody. Nonspecific collision of exposed membrane lipid regions occurs during immune PEL-TC interaction. Binding of cytotoxic lymphocytes and TC is probably preceded by an unstable and nonspecific hydrophobic interaction of cells, which facilitates specific and stable binding. Changes in the composition of membrane lipid constituents prevent binding of PEL and TC.