The Biophysics of T Lymphocyte Activation In Vitro and In Vivo

Junior Research Group of Immunodynamics, German Research Centre for Biotechnology (GBF), Braunschweig, Germany.
Results and problems in cell differentiation 02/2006; 43:199-218. DOI: 10.1007/400_021
Source: PubMed


T cell activation is crucial for the development of specific immune reactions. It requires physical contact between T cells and antigen-presenting cells (APC). Since these cells are initially located at distinct positions in the body, they have to migrate and find each other within secondary lymphoid organs. After encountering each other both cells have to maintain a close membrane contact sufficiently long to ensure successful signaling. Thus, there is the necessity to temporarily synchronize the motile behavior of these cells. Initially, it had been proposed that during antigen recognition, T cells receive a stop signal and maintain a stable contact with APC for several hours when an appropriate APC has been encountered. However, direct cell observation via time-lapse microscopy in vitro and in vivo has revealed a different picture. While long contacts can be observed, many interactions appear to be very short and sequential despite efficient signaling. Thus, two concepts addressing the biophysics of T cell activation have emerged. The single encounter model proposes that after a period of dynamic searching, a T cell stops to interact with one appropriately presenting APC until signaling is completed. The serial encounter model suggests that T cells are able to collect a series of short signals by different APC until a critical activation threshold is achieved. Future research needs to clarify the relative importance of short and dynamic versus long-lived T cell-APC encounters for the outcome of T cell activation. Furthermore, a thorough understanding of the molecular events underlying the observed complex motility patterns will make these phenomena amenable for intervention, which might result in the identification of new types of immune modulating drugs.

Download full-text


Available from: Matthias Gunzer, Jan 13, 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: The movement of immune cells is an indispensable prerequisite for their function. All essential steps of cellular immunity rely on the ability of cells to migrate and to interact with each other. Although observation of these phenomena in vivo would be the most physiological approach, intravital imaging is technically very demanding and not optimally suited for routine or high-throughput analysis. Any good in vitro experimental system should reflect the inherent three-dimensionality of cell migration and interaction in living tissues. Data generated over the last decade show that important cellular parameters like cell velocity, cell shape, and the physicodynamics of cell-cell interactions closely resemble values observed in vivo when measured in a three-dimensional (3D) collagen matrix assay, featuring a hydrated network of fibers consisting of type I collagen, the major component of the extracellular matrix. In this chapter, we describe in detail the experimental use of the 3D collagen matrix system. We delineate the preparation of immune cells exemplified by bone marrow-derived dendritic cells and antigen specific T-helper cells of the mouse, the build-up and use of the 3D collagen matrix chamber, the procedures of real time fluorescence microscopic analysis of cell migration and cell-cell interaction, as well as data analysis supported by a self-developed software for computer-assisted cell tracking.
    No preview · Article · Feb 2007 · Methods in Molecular Biology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Skin wart is a lesion caused by human papilloma viruses (HPVs) that can infect both male and female. Quantify the number of CD28+, CD86+, CD152+ and gammadelta+ in peripheral blood mononuclear cells (PBMCs) of subjects with skin wart. Identify CD86+ and gammagamma+ cells in skin wart cryosections. Sixteen subjects with skin warts on face, hand, finger, knee, foot or plantar, both male and female, aged between 19-59 years-old, were recruited from Ramathibodi Hospital, Mahidol University, Bangkok. CD86 and CD152, on peripheral blood mononuclear cells (PBMCs) of subjects with skin wart are significantly lower compared to controls. Tissue cryosection staining for CD86+ and gammadelta+ cells showed no difference among subjects with skin wart and control. Proliferative response to poke weed mitogen of subjects with skin wart is significantly lower than control subjects. There was no difference in the number of subjects positive for CD28 and CD86 cell between normal and skin wart subject, but an increase in skin wart subjects with gammadelta+ cells.
    Full-text · Article · Oct 2007 · Journal of the Medical Association of Thailand = Chotmaihet thangphaet
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Two-photon microscopy is indispensable for deep tissue and intravital imaging. However, current technology based on single-beam point scanning has reached sensitivity and speed limits because higher performance requires higher laser power leading to sample degradation. We utilize a multifocal scanhead splitting a laser beam into a line of 64 foci, allowing sample illumination in real time at full laser power. This technology requires charge-coupled device field detection in contrast to conventional detection by photomultipliers. A comparison of the optical performance of both setups shows functional equivalence in every measurable parameter down to penetration depths of 200 microm, where most actual experiments are executed. The advantage of photomultiplier detection materializes at imaging depths >300 microm because of their better signal/noise ratio, whereas only charge-coupled devices allow real-time detection of rapid processes (here blood flow). We also find that the point-spread function of both devices strongly depends on tissue constitution and penetration depth. However, employment of a depth-corrected point-spread function allows three-dimensional deconvolution of deep-tissue data up to an image quality resembling surface detection.
    Full-text · Article · Oct 2007 · Biophysical Journal
Show more