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F Dallegri, F Patrone, G Frumento, A Ballestrero and C Sacchetti
Human neutrophils, activated by phorbol-myristate acetate (PMA), (A-
neutrophils), were found to suppress lymphocytic killer (K) cell- mediated
antibody-dependent cellular cytotoxicity (ADCC). Resting (R) neutrophils,
ie, PMA-untreated cells, were completely ineffective. Suppression was
optimal when A-neutrophils were added at the beginning of the ADCC assay.
Furthermore, A-neutrophils were found to cause an approximately 80%
reduction in the number of Raji target cell-bound lymphocytes. These data
indicate that A-neutrophils inhibit K cell activity by interfering with the
target cell recognition. A-neutrophils were capable of reducing the
percentage of Fc receptor (FcR)-bearing lymphocytes with a half-time of 7.2
minutes, through a process preventable by the serine-protease inhibitors
tosyl-lysine-chloromethyl ketone (TLCK) and lima bean trypsin inhibitor
(LBTI). Conversely, A- neutrophils caused a very slow decrease in the
amount of Raji cell- bound antibodies, as detected by the
complement-mediated lytic assay. Thus, only lymphocyte FcR structures seem
to be highly susceptible to neutrophil-derived TLCK- and LBTI-inhibitable
proteases. Furthermore, supernatants from A-neutrophils were found to
inhibit K cell ADCC and lymphocyte binding to Raji target cells. In
addition, LBTI prevented the A-neutrophil-dependent and the
supernatant-dependent inhibition of both K cell ADCC activity and
lymphocyte-target cell conjugate formation. Together these data suggest
that A-neutrophils suppress K cell function through a protease-mediated
impairment of the FcR binding capacity. The results provide evidence that
human neutrophils are endowed with mechanisms to regulate K cell ADCC
activity.
This article has been cited by other articles:
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| Copyright © 1985 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
