Appearance of soluble CD23 in the supernatant after lymphocyte exposure to BzATP but not PMA. Lymphocytes were treated with 100 nmol/L PMA (lanes 1 and 2) or 0.2 mmol/L BzATP (lanes 3 and 4) for 30 minutes. CD23 was detected in supernatants (lanes 1 and 3) or cell lysates (lanes 2 and 4) by Western blotting. Lane 5 is a cell lysate of untreated lymphocytes. No bands were detected using an irrelevant control antibody.