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Endocytosis of ß2 integrins by stimulated human neutrophils analyzed by flow cytometry
Author(s) -
Chambers J. David,
Simon Scott I.,
Berger Elaine M.,
Sklar Larry A.,
Arfors KarlE.
Publication year - 1993
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.53.4.462
Subject(s) - endocytosis , biology , flow cytometry , cd18 , integrin , microbiology and biotechnology , receptor , receptor mediated endocytosis , monoclonal antibody , biophysics , biochemistry , antibody , immunology
Flow cytometry and fluorescently labeled monoclonal antibodies were used to investigate endocytosis of human neutrophil ß2 integrins following cellular activation. GDI 8 initially present on the cell surface cycled in two phases after exposure to formyl peptide or plateletactivating factor. The first phase lasted 3 min at 37°C; after a lag, CD18 was specifically internalized at approximately 20%/min. Subsequently a second phase was detectable consisting of exponential reduction of internal fluorescence with a half‐time of approximately 2 min, representing probe reexpression. At peak endocytosis approximately 40% of CD18 was internalized. All of the internalized CD18 was associated with αM (CR3); no endocytosis of αL (LFA‐1) was observed. When neutrophils were stimulated with phorbol esters or calcium iono‐ phore, CD18 was internalized much more slowly (t1/2 = 5 min) and probe was not reexpressed. Endocytosis of CD18 may participate in regulating neutrophil adhesiveness, removing activated receptors, or permitting receptor recycling.