Engagement of CD45 during in vitro priming enhances antigen-specific Th cell frequencies.
CD45 is a transmembrane protein tyrosine phosphatase expressed by all lymphoid cells including T cells. Substantial experimental data has shown that CD45 maintains a permissive state for TCR signaling. The highly glycosylated extracellular domain of CD45 may be the site of interaction with regulatory lectin-like counter-receptors on antigen-presenting cells. The mAb NDA5, recognizing a unique but broadly distributed epitope of CD45, was used to study the possible immunoregulatory role of CD45 during anti-CD3 and antigen-specific CD4+ T cell activation. In vitro priming of peripheral blood mononuclear cells with peptide antigens in the presence of mAb NDA5 results in a higher frequency of antigen-specific T cells. The responses of both naive and memory T cells to peptide antigens were sensitive to mAb NDA5-enhanced priming. Anti-CD3 activation of normal resting T cells, in the presence of mAb NDA5, resulted in enhancement of tyrosine phosphorylation of specific intracellular proteins associated with TCR signal transduction. In cultures without antigen, mAb NDA5 down-regulated the cell surface expression of both CD3 and CD4, yet did not stimulate proliferation of resting T cells. Together these results suggest that engagement of CD45 during in vitro priming has a significant effect on the development of antigen-specific T cell populations.
Harris
P E
PE
Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10027, USA.
Liu
Z
Z
Colovai
A I
AI
Kinne
J
J
Maffei
A
A
Febles
A
A
Suciu-Foca
N
N
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000941:Antigens / Q000378:metabolism*; D017252:CD3 Complex / Q000378:metabolism; D015704:CD4 Antigens / Q000378:metabolism; D002462:Cell Membrane / Q000276:immunology; D002999:Clone Cells; D066298:In Vitro Techniques; D017493:Leukocyte Common Antigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000941:Antigens; D017252:CD3 Complex; D015704:CD4 Antigens; D011506:Proteins; D014443:Tyrosine; D017493:Leukocyte Common Antigens