AJP - Cell Physiology, Vol 262, Issue 4 C916-C926, Copyright © 1992 by American Physiological Society
Lymphocyte adhesion can be regulated by cytoskeleton-associated, PMA-induced capping of surface receptors
D. M. Haverstick, H. Sakai and L. S. Gray
Department of Pathology, University of Virginia Health Sciences Center, Charlottesville 22908.
Intercellular adhesion in lymphocytes is mediated in part by the
interaction of the integrin lymphocyte function-associated antigen-1
(LFA-1) with intercellular adhesion molecule-1 (ICAM-1). The B
lymphoblastoid line JY expresses both LFA-1 and ICAM-1, and intercellular
adhesion is enhanced by treatment with the phorbol ester phorbol
12-myristate 13-acetate (PMA), which also induced capping of LFA-1, ICAM-1,
and human leukocyte antigen. Capping of LFA-1 is likely to result from
protein kinase C (PKC) activation because receptor-mediated stimulation of
PKC also led to capping. Additionally, adhesion mediated by PMA or
lipopolysaccharide was blocked by either of two PKC inhibitors, calphostin
C and staurosporine. PMA induced the apparent condensation of cytoskeletal
elements that colocalized with the membrane protein cap. Cytoskeletal
condensation and capping occurred in the absence of intercellular adhesion.
Alteration in the distribution of cytoskeletal components and membrane
redistribution of LFA-1 were inhibited by cytochalasin D, which also
abolished intercellular adhesion. Taken together, these data suggest that
intercellular adhesion is the result of PKC-mediated membrane
redistribution of LFA-1 and ICAM-1, which is in turn associated with
modification of the actin-based cytoskeleton.
