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A novel anti‐rat CD18 monoclonal antibody triggers lymphocyte homotypic aggregation and granulocyte adhesion to plastic: Different intracellular signaling pathways in resting versus activated thymocytes
Author(s) -
Pavlovi Miloš D.,
Čolić Miodrag,
Pejnović Nada,
Tamatani Takuya,
Miyasaka Masayuki,
Dujić Aleksandar
Publication year - 1994
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.1830240728
Subject(s) - biology , cd18 , intracellular , microbiology and biotechnology , monoclonal antibody , adhesion , granulocyte , lymphocyte , immunology , signal transduction , intercellular adhesion molecule 1 , cell adhesion , antibody , cell , biochemistry , chemistry , organic chemistry
Abstract We have raised a monoclonal antibody (mAb), NG2B12, directed against rat CD18, capable of inducing lymphocyte homotypic adhesion and granulocyte adherence to plastic. NG2B12‐induced aggregation is temperature sensitive and requires metabolic energy, an intact cytoskeleton and the presence of Mg 2+ , but is independent of protein synthesis. Ca 2+ is not only dispensable but exerts a suppressive effect on the NG2B12‐induced adhesion. The adhesion is readily observed in thymocytes and concanavalin A blasts of thymocytes and splenocytes but is very weak in resting spleen and lymph node cells. NG2B12 also enhances phorbol 12‐myristate 13‐acetate (PMA)‐induced aggregation in an additive fashion. The NG2B12‐induced homotypic adhesion is mediated by LFA‐1. mAb against ICAM‐1 completely inhibited the induced adhesion of activated cells but inhibited only partially and in a time‐dependent manner the adhesion of resting thymocytes. The activation of protein phosphatases 1 and 2A (as assessed by the use of okadaic acid) is necessary for the NG2B12‐induced adhesion of both resting and activated thymocytes. In contrast, H‐7 (an inhibitor of protein kinase C and A), substantially suppressed the adhesion of resting thymocytes, whereas W‐7 (an inhibitor of calmodulin‐dependent protein kinase) inhibited the adhesion of activated thymocytes. NG2B12 induces both adherence to plastic and homotypic aggregation of granulocytes; the events being blocked by anti‐CD18 (WT.3) and anti‐CD11b/CD11c (OX‐42) mAb, augmented by okadaic acid and not modified by H‐7 and W‐7. Additionally, we have demonstrated that NG2B12 and PMA employ distinct intracellular signaling pathways in inducing adhesion of both thymocytes and granulocytes.