Ligation of CD4 concomitant to activation induces primary CD4+ T-cell adhesion and pseudopodia formation in vitro.
A regulatory function for CD4 molecules in lymphocyte adhesion and motility was investigated. Murine splenic CD4+ T cells, activated in the presence of phorbol ester and immobilized anti-CD4 mAb, adhered to the plastic surface and formed extended cytoplasmic projections (pseudopodia). Pseudopod formation was cell-density-dependent, peaked at Day 3, and disappeared by Day 5 in culture. This response could be inhibited by soluble anti-CD4 and by RGD-containing peptide. Ligation of CD4 was required at a late stage in cell activation, and stimulated cell motility in vitro. Addition of IL-4, but not IL-2, upregulated pseudopod formation induced by suboptimal stimuli. Anti-IL-4 mAb blocked pseudopod formation, and exogenous IL-4 restored the response. A combination of IL-4 plus phorbol ester, but not IL-2 plus phorbol ester, induced pseudopod formation in concert with CD4 ligation. Exogenous IL-2, on the other hand, blocked pseudopod formation. CD45RBlow CD4+ T cells were much more efficient than CD45RBhigh CD4+ T cells for pseudopod formation. These results indicate that CD4 ligation induces CD4+ T-cell adhesion and motility, mainly in the memory/activated subset, which might be relevant for immune responses in vivo.
Palomo
L F
LF
Departamento de Imunologia, Universidade Federal do Rio de Janeiro, Brazil.
Decoté-Ricardo
D
D
Pirmez
C
C
Vieira
R M
RM
DosReis
G A
GA
D000818:Animals; D015704:CD4 Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002448:Cell Adhesion; D002452:Cell Count; D002465:Cell Movement; D002478:Cells, Cultured; D007156:Immunologic Memory; D015847:Interleukin-4 / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D011554:Pseudopodia; D013154:Spleen / Q000166:cytology / Q000276:immunology
D015704:CD4 Antigens; D015847:Interleukin-4