Document 0131
 DOCN  M95B0131
 TI    The outer surface lipoprotein A of Borrelia burgdorferi provides direct
       and indirect augmenting/co-stimulatory signals for the activation of
       CD4+ and CD8+ T cells.
 DT    9511
 AU    Simon MM; Nerz G; Kramer MD; Hurtenbach U; Schaible UE; Wallich R;
       Max-Planck-Institut fur Immunbiologie, Freiburg, Germany.
 SO    Immunol Lett. 1995 Feb;45(1-2):137-42. Unique Identifier : AIDSLINE
       MED/95347755
 AB    Naive CD4+ and CD8+ T cells require two distinct signals to proliferate
       and to express effector functions [1]. One is provided by the antigen
       receptor on the T cell (TCR) after its encounter with antigenic peptides
       associated with class I or II major histocompatibility complex (MHC)
       molecules on antigen-presenting cells (APC) [2]. The second signal,
       which is not antigen-specific but essential for proliferation and
       differentiation of naive T cells, is provided by co-stimulatory
       structures. The major co-stimulatory molecules for CD4+ T cells seem to
       be B7 [3], B7.2 [4,5], and heat-stable antigen (HSA) [6]. These
       molecules are expressed on a variety of naive and/or activated APC and
       bind to CD28 and CTLA-4 and possibly other, as yet undefined, TCRs
       [3,7]. Optimal T cell activation only occurs when co-stimulatory
       molecules and ligands for the TCR are expressed on the same APC [8,9].
       However, co-stimulation for T cells may also be provided via bystander
       cells [8,9] or by glycoproteins of the extracellular matrix, like
       fibronectin [10] and laminin [11]. In this case, T-cell VLA integrins
       function as signaling molecules [10,11]. This indicates that
       antigen-specific T-cell activation may also occur in areas where
       antigens are presented in association with extracellular matrix
       proteins. The recent finding that the invasion protein of Yersinia spp.
       delivers co-stimulatory signals to anti-CD3-activated human T cells,
       most probably through the b1 integrins, suggests that bacterial products
       can also bind to contribute to the activation of T cells [12].(ABSTRACT
       TRUNCATED AT 250 WORDS)
 DE    Animal  Antigens, Bacterial/*IMMUNOLOGY  Antigens, CD3/*IMMUNOLOGY
       Antigens, Surface/*IMMUNOLOGY  Bacterial Outer Membrane
       Proteins/*IMMUNOLOGY  Borrelia burgdorferi/*IMMUNOLOGY  Cell
       Differentiation  Cells, Cultured  CD4-Positive T-Lymphocytes/*IMMUNOLOGY
       CD8-Positive T-Lymphocytes/*IMMUNOLOGY  *Lymphocyte Transformation  Mice
       Mice, Inbred C57BL  Muromonab-CD3/PHARMACOLOGY  Signal Transduction
       Support, Non-U.S. Gov't  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).