A Third Measure-Metastable State in the Dynamics of Spontaneous Shape Change in Healthy Human's White Cells

Human polymorphonuclear leucocytes, PMN, are highly motile cells with average 12-15 µm diameters and prominent, loboid nuclei. They are produced in the bone marrow, are essential for host defense, and are the most populous of white blood cell types. PMN also participate in acute and chronic inflammatory processes, in the regulation of the immune response, in angiogenesis, and interact with tumors. To accommodate these varied functions, their behavior is adaptive, but still definable in terms of a set of behavioral states. PMN morphodynamics have generally involved a non-equilibrium stationary, spheroid Idling state that transitions to an activated, ellipsoid translocating state in response to chemical signals. These two behavioral shape-states, spheroid and ellipsoid, are generally recognized as making up the vocabulary of a healthy PMN. A third, “random” state has occasionally been reported as associated with disease states. I have observed this third, Treadmilling state, in PMN from healthy subjects, the cells demonstrating metastable dynamical behaviors known to anticipate phase transitions in mathematical, physical, and biological systems. For this study, human PMN were microscopically imaged and analyzed as single living cells. I used a microscope with a novel high aperture, cardioid annular condenser with better than 100 nanometer resolution of simultaneous, mixed dark field and intrinsic fluorescent images to record shape changes in 189 living PMNs. Relative radial roundness, R(t), served as a computable order parameter. Comparison of R(t) series of 10 cells in the Idling and 10 in the Treadmilling state reveals the robustness of the “random” appearing Treadmilling state, and the emergence of behaviors observed in the neighborhood of global state transitions, including increased correlation length and variance (divergence), sudden jumps, mixed phases, bimodality, power spectral scaling and temporal slowing. Wavelet transformation of an R(t) series of an Idling to Treadmilling state change, demonstrated behaviors concomitant with the observed transition

Contains recurrence plots, RP_i,j, of four representative PMNs in the <i>Idling</i> state (top row) and four in the <i>Treadmilling</i> state (bottom row).

<p>ε = 1 for all plots.</p

Observed cell state transitions.

<p>Observed cell state transitions.</p

Representative binary color coded silhouettes of PMNs in round <i>Idling</i>, <i>Treadmilling</i> and elliptically polarized/translocating shape-states.

<p>Representative binary color coded silhouettes of PMNs in round <i>Idling</i>, <i>Treadmilling</i> and elliptically polarized/translocating shape-states.</p

Measures made on a nutrophil before and after idling to treadmilling state change.

<p><a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1001117#pcbi-1001117-t002" target="_blank"><b>Table 2</b></a> reports the results of the same measures listed in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1001117#pcbi-1001117-t001" target="_blank"><b>Table 1</b></a>, this time made on the <i>R</i>(t) series of a single PMN first in an <i>Idling</i> state and then in a <i>Treadmilling</i> state. This PMN also remained healthy for the 30 min recording period and made no contact with extracellular bodies during that time.</p

Shows a “close-up” of a PMN during a phase transition.

<p>The upper panel shows the <i>R</i>(t) series, while the lower panel depicts the continuous 1D Morlet wavelet moduli for that time interval (x-axis). Scale of the basis function increases up the y-axis. The colormap passes through the visible spectrum; blues representing low Morlet moduli amplitudes to high valued reds. The cell is initially <i>Idling</i>, and begins <i>Treadmilling</i> at data point t = 283. Note that anticipatory slow high amplitude fluctuations begin to appear at about point t = 198.</p

Measure averages for cells in each state group.

<p><a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1001117#pcbi-1001117-t001" target="_blank"><b>Table 1</b></a> reports the results of measures made on the <i>R</i>(t) series of ten <i>Idling</i> PMN and ten <i>Treadmilling</i> PMN, all of which had remained healthy and in a single behavioral state for the 30 min recording period and made no contact with extracellular bodies during that time.</p