The Requirement for Esterase Activation in the Anti-Immunoglobulin-Triggered Movement of B Lymphocytes

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Abstract
In this paper we bring evidence suggesting that there is activation of an esterase upon reaction of anti-immunoglobulin antibodies (anti-Ig) with murine B lymphocytes. B lymphocytes upon exposure to anti-Ig cap the ligand-receptor complexes and immediately afterward become briefly motile. It is this latter step which is inhibitable by exposure to di-isopropyl phosphofluoridate (DFP). Various experimental manipulations indicated that treatment with anti-Ig activates the cell for motility which, however, is not manifested until the temperature is raised to 37°C. The cell incubated with anti-Ig at cold temperatures becomes susceptible to the effect of DFP, suggesting that the antibody-treated cells are activated up to but not beyond the DFP inhibitable step. Exposure of cells to DFP and removal of it before their treatment with anti-Ig does not affect the anti-Ig-induced response. Four lines of evidence indicate that the reduction of lymphocyte movement by DFP is due to the inhibition of an esterase activated by the combination of antibody and cell: 1) The inhibition by DFP is irreversible; once DFP has reacted it can be washed away and the antibody-treated cell is still inhibited. 2) The inhibition increases with time of contact of lymphocytes and DFP and with the concentration of DFP. 3) A very poorly phosphorylating phosphonate, phenyl ethyl pentylphosphonate is completely inactive under conditions where an excellent phosphorylating phosphonate, p nitrophenyl ethyl pentyl-phosphonate maximally inactivated the cells' movement. 4) The amino acid esters, tosyl L arginine methyl ester and benzoyl arginine methyl ester specifically prevent the inactivation by DFP. The last finding suggests that tosyl L arginine methyl ester and benzoyl L arginine methyl ester might be substrates for the putative antibody-induced lymphocyte esterase. Lymphocytes incubated with antibody in the cold for more than 30 min lose their ability to move when the temperature is raised, suggesting that there is a time-dependent deactivation of the cell.

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