Membrane Immunology and Permeability Functions

Lauf, Peter K.

doi:10.1007/978-1-4757-1718-1_20

Cited by 3 publications

(6 citation statements)

References 121 publications

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“…By comparison, the lytic activity of these proteins towards erythrocytes with high Na § content (LK RBC) was always increased with respect to HK RBC and was only slightly influenced by the extracellular cation [2,4,6]. The effect of hypotonic and hypertonic media on the complementmediated hemolysis of sheep HK and LK RBC has been extensively studied by Lauf [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…The equilibration of Na § and K § across the C5b-9 damaged plasma membrane is accompanied by the colloidosmotic expansion of cell water, leading ultimately to its hydrostatic rupture and cell death [13,19]. Evidence for a direct membranolytic activity of these proteins (independent of osmotic water movement) has also been considered [10,32].…”

Section: Introductionmentioning

confidence: 99%

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The influence of electrochemical gradients of Na+ and K+ upon the membrane binding and pore forming activity of the terminal complement proteins

Sims

Wiedmer

1984

J. Membrain Biol.

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The hemolytic activity of the terminal complement proteins (C5b-9) towards erythrocytes containing high potassium concentration has been reported to be dramatically increased when extracellular Na+ is substituted isotonically by K+ (Dalmasso, A.P., et al., 1975, J. Immunol. 115:63-68). This phenomenon was now further investigated using resealed human erythrocyte ghosts (ghosts), which can be maintained at a nonlytic osmotic steady state subsequent to C5b-9 binding: (1) The functional state of C5b-9-treated ghosts was studied from their ability to retain trapped [14C]-sucrose or [3H]-inulin when suspended either in the presence of Na+ or K+. A dramatic increase in the permeability of the ghost membrane to both nonelectrolytes - in the absence of significant hemoglobin release - was observed for C5b-9 assembly in the presence of external K+. (2) The physical binding of the individual 125I-labeled terminal complement proteins to ghost membranes was directly measured as a function of intra- and extracellular K+ and Na+. The uptake of 125I-C7, 125I-C8, and 125I-C9 into membrane C5b-9 was unaltered by substitution of Na+ by K+. (3) The binding of the terminal complement proteins to ghosts subjected to a transient membrane potential generated by the K+-ionophore valinomycin (in the presence of K+ concentration gradients) was measured. No significant change in membrane binding of any of the C5b-9 proteins was detected under the influence of both depolarizing and hyperpolarizing membrane potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of electrochemical gradients of Na+ and K+ upon the membrane binding and pore forming activity of the terminal complement proteins

Sims

Wiedmer

1984

J. Membrain Biol.

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“…The possibility that this putative transmembrane channel might selectively conduct potassium (versus sodium) was suggested by: (i) the enhanced lysis observed when C5b-9-treated erythrocytes are suspended in isotonic KC1 versus NaC1, which we have recently shown reflects an effect on the target cell which is exerted after the binding of the C5b-9 proteins (Dalmasso et al, 1975;Sims & Wiedmer, 1984); (ii) the differential effect of anisoosmotic solutions of KC1 versus NaC1 on the kinetics of complement-mediated hemolysis (Lauf, 1975;1978); (iii) data pertaining to the molecular exclusion size of the C5b-9 pore, which suggest a minimum pore radius of <4 A (Sims & Lauf, 1978;1980); (iv) recent analysis of the single-channel conductance associated with binding of the C9b fragment of complement protein C9 to lipid bilayer membranes, which indicates a K/Na selectivity ratio of 3.5 : 1 (Esser et al,, 1984).…”

Section: Discussionmentioning

confidence: 94%

“…2 and 3). In this context it is interesting to note that on the basis of apparent osmotic permeabilities measured for complement-treated red cells, Lauf (1978) also concluded that the net flux of ions across the C5b-9 membrane pore must be limiting to the rate of immune hemolysis. …”

Section: Membrane Potential Changes Initiated By the Binding Of C8 Anmentioning

confidence: 98%

“…Furthermore, there is now increasing evidence to suggest that initial changes in the electrochemical state of the cell upon C5b-9 binding, including changes in the transmembrane electrochemical potential and the levels of intracellular Ca ++ and ATP, may significantly determine the ultimate extent of plasma membrane damage and its consequence for normal cellular function and survival (Esser, 1980;Campbell et al, 1981;Hailer & Campbell, 1984;Tirosh & Berke, 1984). In this context, changes in plasma membrane integrity arising secondarily to the colloid-osmotic influx of water (Lauf, 1975;1978), or due to the release of free fatty acids by activated endogenous phospholipases (Imagawa et al, 1983) are each likely to contribute to the apparent 'pore properties' of the C5b-9 membrane complex as detected solely by the efflux of trapped marker solute.…”

Section: Introductionmentioning

confidence: 99%

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Cyanine dye fluorescence used to measure membrane potential changes due to the assembly of complement proteins C5b-9

Wiedmer

Sims

1985

J. Membrain Biol.

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The fluorescent potentiometric indicator diS-C3-(5) has been used to investigate changes in membrane potential due to assembly of the C5b-9 membrane attack complex of the complement system. EAC1-7 human red blood cells and resealed erythrocyte ghosts--bearing membrane-assembled C5b67 complexes--were generated by immune activation in C8-deficient human serum. Studies performed with these cellular intermediates revealed that the membrane potential of EAC1-7 red cells and ghosts is unchanged from control red cells (-7 mV) and ghosts (O mV), respectively. Addition of complement proteins C8 and C9 to EAC1-7 red cells results in a dose-dependent depolarization of membrane potential which precedes hemolysis. This prelytic depolarization of membrane potential--and the consequent onset of hemolysis--is accelerated by raising external [K+], suggesting that the diffusional equilibration of transmembrane cation gradients is rate limiting to the cytolytic event. In the case of EAC1-7 resealed ghosts suspended at either high external [K+] or [Na+], no change in membrane potential (from O mV) could be detected after C8/C9 additions. When the membrane potential of the EAC1-7 ghost was displaced from O mV by selectively increasing the K+ conductance with valinomycin, a dose-dependent depolarization of the membrane was observed upon addition of C8 and C9. In these experiments, lytic breakdown of the ghost membranes was less than 5%. Conclusions derived from this study include: (i) measured prelytic depolarization of the red cell Donnan potential directly confirms the colloid-osmotic theory of immune cytolysis. (ii) The diffusional transmembrane equilibration of Na+ and K+ through the C5b-9 pore results in a dose-dependent depolarization of the membrane potential (Em) which appears to be rate-limiting to cytolytic rupture of the target erythrocyte. (iii) Enhanced immune hemolysis observed in high K+ media cannot be attributed to cation-selective conductance across the C5b-9 pore, and is probably related to the near-equilibrium condition of potassium-containing red cells when suspended at high external K+. These experiments demonstrate that carbocyanine dye fluorescent indicators can be used to monitor electrochemical changes arising from immune damage to the plasma membrane under both cytolytic and noncytolytic conditions. Potential application of this method to the detection of sublytic pathophysiological changes in the plasma membrane of complement-damaged cells are discussed.

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Single-channel analysis of the conductance fluctuations induced in lipid bilayer membranes by complement proteins C5b-9

et al. 1986

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Single-channel analysis of electrical fluctuations induced in planar bilayer membranes by the purified human complement proteins C5b6, C7, C8, and C9 have been analyzed. Reconstitution experiments with lipid bilayer membranes showed that the C5b-9 proteins formed pores only if all proteins were present at one side of the membrane. The complement pores had an average single-channel conductance of 3.1 nS at 0.15 M KCl. The histogram of the complement pores suggested a substantial variation of the size of the single channel. The linear relationship between single-channel conductance at fixed ionic strength and the aqueous mobility of the ions in the bulk aqueous phase indicated that the ions move inside the complement pore in a manner similar to the way they move in the aqueous phase. The minimum diameter of the pores as judged from the conductance data is approximately 3 nm. The complement channels showed no apparent voltage control or regulation up to transmembrane potentials of 100 mV. At neutral pH the pore is three to four times more permeable for alkali ions than for chloride, which may be explained by the existence of fixed negatively charged groups in or near the pore. The significance of these observations to current molecular models of the membrane lesion formed by these cytolytic serum proteins is considered.

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Membrane Immunology and Permeability Functions

Cited by 3 publications

References 121 publications

The influence of electrochemical gradients of Na+ and K+ upon the membrane binding and pore forming activity of the terminal complement proteins

The influence of electrochemical gradients of Na+ and K+ upon the membrane binding and pore forming activity of the terminal complement proteins

Cyanine dye fluorescence used to measure membrane potential changes due to the assembly of complement proteins C5b-9

Single-channel analysis of the conductance fluctuations induced in lipid bilayer membranes by complement proteins C5b-9

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