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1

Structure and function of T lymphocyte TCR/CD3 complex

100%
Bocko D., Frydecka I.
Postępy Higieny i Medycyny Doświadczalnej
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2003
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vol. 57
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issue 5
519-529
EN
The multichain T cell receptor/CD3 complex (TCR/CD3) plays a key role in antigen recognition, further T cell activation and in consequence in triggering an antigen specific immune response. This process is induced by direct interaction of the TCR receptor with an antigen bound to the major histocompatibile compex on antigen-presenting cells. Upon the structural and functional cooperation of TCR receptor with CD3 complex, the activating signal is transmitted through the cell membrane to the nucleus. The pivotal role in signaling cascade plays CD3-zeta () chain, which triggers many biochemical events and second messenger activation, leading to the transcriptional factors expression and further T cell proliferation, effector function augmentation and cytokine production.
2

Expression and functional significance of CTLA-4, a negative regulator of T cell activation

81%
Kosmaczewska A., Ciszak L., Bocko D., Frydecka I.
Archivum Immunologiae et Therapiae Experimentalis
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2001
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vol. 49
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issue 1
39-46
EN
The generation of an effective immune response involves antigen-specific T cell expansion and differentiation of effector function. T cell activation requires at least two distinct signals, including signaling via the Ag-specific TCR and a costimulatory pathway. Antigen stimulation of T cells can lead either to a productive immune response characterized by proliferation, differentiation, clonal expansion and effector function or, in absence of appropriate costimulation, to a state of long-lasting unresponsiveness termed anergy. Anergic T cells fail to proliferate and secrete cytokines in response to secondary stimulation. The interaction between costimulatory molecule CD28 on T cells with members of the B7 family on APC results in upregulation of T cell proliferation, cytokine production and induces the expression of the anti-apoptotic protein Bcl-xl. Based of those findings, the two-signal requirement model for T cell activation is today generally accepted. The negative regulatory mechanisms during T cell activation are not well understood, but they are crucial for the maintainance of lymphocyte homeostasis. For several years the functional role of the enigmatic CD28 homologue CTLA-4 (cytotoxic T lymphocyte antigen-4) in T cell activation has been both obscure and conteroversional. CTLA-4 was initially proposed to provide a costimulatory signal in conjunction with TCR/CD3 signaling. Today we know that CD28 and CTLA-4 molecules may have diametrically opposed functions: signaling via CD28, in conjunctive with TCR, is required for T cell activation, while signaling via CTLA-4 is a negative signal that inhibits T cell proliferation. How the T cell integrates signals through the TCR/CD3 complex, CD28 and CTLA-4 to initiate, maintain and terminate antigen-specific immune response is actually not fully clarified. In this review, we will focus on the emerging role of CTLA-4 as a negative regulator of T lymphocyte activation and its role in dynamic interplay of activatory and inhibitory signals.
3

CD28 costimulatory molecule - expression, structure and function

71%
Bocko D., Kosmaczewska A., Ciszak L., Teodorowska R., Frydecka I.
Archivum Immunologiae et Therapiae Experimentalis
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2002
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vol. 50
|
issue 3
169-178
EN
T cell activation is a key event triggering an antigen specific immune response of the organism. The process is induced primarily by signal generated by direct interaction of T cell receptor (TCR) with antigen bound to major histocompatibile complex (MHC) on antigen presenting cell (APC). Although the signal is critical to excite immune response, however additional, costimulating signal is required. The major second signal is generated by interaction of CD28 molecule expressed on most T lymphocytes with its natural ligands CD80 and CD86 located on APCs. Signal excited by CD28 triggering involves multiple second messenger cascades, leading to activation of transcription factors and finally results in cell proliferation, cytokine production, and generation of effector function. The importance of CD28-delivered costimulatory signals was proven in experiments with CD28-deficient mice. T cells from these mice exhibit, impaired pattern of cytokine secretion, defects in T cell dependent antibody production. Certain forms of immunopathology might result from the aberrant regulation of CD28 expression.
4

Lack of association between Exon 1 CTLA-4 gene polymorphism A(49)G and multiple sclerosis in Polish population of the Lower Silesia Region

52%
Bocko D., Bilinska M., Dobosz T., Zoledziewska M., Suwalska K., Tutak A., Gruszka E., Frydecka I.
Archivum Immunologiae et Therapiae Experimentalis
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2003
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vol. 51
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issue 3
201-205
EN
Multiple sclerosis (MS) a chronic inflammatory demyelinating disease of the central nervous system (CNS) is believed to have a T-cell mediated autoimmune etiology. The cytotoxic T lymphocyte antigen 4 (CTLA-4) gene is a strong candidate for the involvement in autoimmune diseases because CTLA-4 plays an important role in downregulation of early and late stages of T cell activation and maintenance of peripheral T cell tolerance. To examine the genetic association of the CTLA-4 gene locus with MS, we analyzed exon 1 CTLA-4 gen polymorphism A(49)G in 102 unrelated Polish MS patients in Lower Silesia region and 101 age and sex matched healthy subjects. The distribution of CTLA-4 exon 1 A(49)G genotype, phenotype and allele frequencies did not differ between patients with MS and healthy subjects.
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