Lytic units reconsidered: Pitfalls in calculation and usage

Pollock, Raphael E.; Zimmerman, Stuart O.; Fuchshuber, Pascal; Lotzová, Eva

doi:10.1002/jcla.1860040408

Cited by 41 publications

(27 citation statements)

References 10 publications

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“…These two metrics provide absolute descriptors of target susceptibility at the limit of a single effector cell and, therefore, allow direct comparison across target lines or conditions. In contrast, bulk lysis-release metrics are influenced by cell lysis properties (18), dependent on the exact E: T ratio, and ambiguous in their interpretation (19).…”

Section: Resultsmentioning

confidence: 99%

Imaging burst kinetics and spatial coordination during serial killing by single natural killer cells

Choi

Mitchison

2013

Proc. Natl. Acad. Sci. U.S.A.

109

114

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Cytotoxic lymphocytes eliminate virus-infected and cancerous cells by immune recognition and killing through the perforin-granzyme pathway. Traditional killing assays measure average target cell lysis at fixed times and high effector:target ratios. Such assays obscure kinetic details that might reveal novel physiology. We engineered target cells to report on granzyme activity, used very low effector:target ratios to observe potential serial killing, and performed low magnification time-lapse imaging to reveal time-dependent statistics of natural killer (NK) killing at the single-cell level. Most kills occurred during serial killing, and a single NK cell killed up to 10 targets over a 6-h assay. The first kill was slower than subsequent kills, especially on poor targets, or when NK signaling pathways were partially inhibited. Spatial analysis showed that sequential kills were usually adjacent. We propose that NK cells integrate signals from the previous and current target, possibly by simultaneous contact. The resulting burst kinetics and spatial coordination may control the activity of NK cells in tissues.

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Section: Resultsmentioning

confidence: 99%

Imaging burst kinetics and spatial coordination during serial killing by single natural killer cells

Choi

Mitchison

2013

Proc. Natl. Acad. Sci. U.S.A.

109

114

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“…Cytotoxicity levels of the different effector-cell concentrations were used for each sample to generate an extrapolated cytotoxicity curve, based on the regression exponential fit method (27). Then, based on the number of NK cells unique to each sample, each curve was shifted horizontally by mathematical transformation of its extrapolated formula and positioned in a cytotoxicity (y) by E:T ratio (x) plot based on its individual NK:target ratio.…”

Section: Comparing Cytotoxicity Per Nk Cellmentioning

confidence: 99%

Improving Survival Rates in Two Models of Spontaneous Postoperative Metastasis in Mice by Combined Administration of a β-Adrenergic Antagonist and a Cyclooxygenase-2 Inhibitor

Glasner

Avraham

Rosenne

et al. 2010

The Journal of Immunology

218

177

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Clinical practice does not consider perioperative paracrine and neuroendocrine stress responses as risk factors for cancer recurrence, although recent animal studies provided supportive evidence. Suggested mechanisms include the effects of stress-hormones on tumor cells and on host physiology. In this study, in mice undergoing primary tumor excision, we tested the survival-enhancing potential of perioperative blockade of catecholamines and prostaglandins, and studied potential mediating mechanisms. C57BL/6J mice were inoculated intrafootpad with syngeneic B16F10.9-melanoma or Lewis lung carcinoma, and the paw was amputated when a developing tumor exceeded 100 μl. The clinically used β-adrenergic antagonist propranolol, and/or the cyclooxygenase-2 inhibitor etodolac, were administered once before amputation, and recurrence-free survival was monitored. In different studies, NK cytotoxicity, leukocytes' molecular functional markers, and vascular endothelial growth factor secretion by tumor cells were studied in the context of surgery and drug treatments. The findings indicated that the combination of propranolol and etodolac, but neither drug alone, significantly and markedly improved survival rates in both tumor models, and was as effective as established immunostimulatory agents (IL-12 and polyinosinic-polycytiylic acid). Surgery markedly reduced NK cytotoxicity and NK cell expression of Fas ligand and CD11a, reduced all circulating lymphocyte-subtype concentrations, and increased corticosterone levels. Propranolol and etodolac administration counteracted these perturbations. B16 and 3LL secreted vascular endothelial growth factor in vitro, but secretion was not affected by catecholamine agonists, prostaglandins, corticosterone, propranolol, or etodolac. Overall, propranolol and etodolac administration, which could be applied perioperatively in most cancer patients with minimal risk and low cost, has counteracted several immunologic and endocrinologic perturbations and improved recurrence-free survival rates in mice undergoing primary tumor excision.

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“…Next, Lytic Units 1/3 (LU 1/3 ) were defined as the concentration of target cells in which this level was achieved in all conditions studied within this blood sample. Particularly, the regression exponential fit method (Pollock et al, 1990) was used to infer LU 1/3 from the empirical data (of percent specific lysis at the six E:T ratios), in respect to baseline levels as well as to each concentration of MP.…”

Section: Lytic Units and Sensitivity Of Nk Activity To Mpmentioning

confidence: 99%

Timing within the menstrual cycle, sex, and the use of oral contraceptives determine adrenergic suppression of NK cell activity

Shakhar

Rosenne

et al. 2000

Br J Cancer

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Physiological responses that involve adrenergic mechanisms, such as stress-induced changes in cardiovascular indices, were reported to fluctuate along the menstrual cycle. Metastatic development following surgery was also reported to vary according to the menstrual phase during which a primary breast tumour was removed. Natural killer (NK) cells are believed to play an important role in controlling metastases. Our recent studies in rats demonstrated that adrenergic suppression of NK activity and of resistance to metastasis is more profound during oestrous phases characterized by high levels of oestradiol. In the current study in humans, we examined the in vitro impact of a β-adrenergic agonist, metaproterenol (MP), on NK activity, comparing blood drawn from (a) women tested at 3–4 different phases of their menstrual cycle ( n = 10), (b) women using oral contraceptives (OC) ( n = 10), and (c) men ( n = 7). NK activity in each blood sample was assessed in the presence of 5 different concentrations of MP (10 –8 M to 10 –6 M), and in its absence (baseline). The results indicated marked group differences in the magnitude of NK suppression by MP: EC 50 was 2.6-fold lower in the luteal phase compared to the follicular phase, and 1.8-fold lower in OC users compared to men, who were least susceptible to the effects of MP. No significant group differences or menstrual effects in baseline levels of NK activity were evident. These findings provide the first empirical evidence for menstrual regulation of adrenergic impact on cellular immune competence. Relevance of these findings to the relation between the timing of breast cancer excision within the menstrual cycle and survival rates is discussed. © 2000 Cancer Research Campaign http://www.bjcancer.com

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Lytic units reconsidered: Pitfalls in calculation and usage

Cited by 41 publications

References 10 publications

Imaging burst kinetics and spatial coordination during serial killing by single natural killer cells

Imaging burst kinetics and spatial coordination during serial killing by single natural killer cells

Improving Survival Rates in Two Models of Spontaneous Postoperative Metastasis in Mice by Combined Administration of a β-Adrenergic Antagonist and a Cyclooxygenase-2 Inhibitor

Timing within the menstrual cycle, sex, and the use of oral contraceptives determine adrenergic suppression of NK cell activity

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