1. Dose-dependent agonist and antagonist effects of the platelet-activating factor analogue 1-palmitoyl-2-acetoyl-sn-glycero-3-phosphocholine on B lymphocytes 
Bruce D. Mazer, MD, Baruch Toledano, MD, Mehrdad Saririan, MD, Yolande Bastien, BSc 
Journal of Allergy and Clinical Immunology 
Volume 102, Issue 2, Pages (August 1998)
DOI: /S (98)
Copyright © 1998 Mosby, Inc. Terms and Conditions

2. Fig. 1
PAF and PAGPC increase IgM secretion in Ramos cells. Ramos cells (3.5 × 105) were cultured for 72 hours with doses of PAF (A) or PAGPC (B) as indicated. Both lipid mediators increased secretion of IgM by Ramos cells in a dose-dependent fashion. Baseline IgM levels ranged from 120 to 360 ng/mL. n = 6. *P ≤ .05.
Journal of Allergy and Clinical Immunology  , DOI: ( /S (98) )
Copyright © 1998 Mosby, Inc. Terms and Conditions

3. Fig. 2
Comparison of the effects of high- and low-dose PAGPC on the PAF receptor. Ramos cells were incubated with PAF (10–7 mol/l), PAGPC (h) (10–6 mol/l), PAGPC (l) (10–12 mol/l), and/or the PAF antagonist Web 2170 (10–6 mol/l). A indicates that Web 2170 inhibits both the effect of PAF 10–9 mol/l and PAGPC (h). B, PAGPC (l) acts as a PAF receptor antagonist, inhibiting the PAF-induced increase of IgM as effectively as Web n = 4. *P ≤ .05.
Journal of Allergy and Clinical Immunology  , DOI: ( /S (98) )
Copyright © 1998 Mosby, Inc. Terms and Conditions

4. Fig. 3
PAGPC inhibits the ability of PAF to rescue Ramos cells from programmed cell death. Ramos cells were incubated with αIgM (2 μg/mL) and/or PAF 10–7 mol/L; indicated cultures were preincubated with PAGPC (l) (10–12 mol/L) or Web 2170 (10–6 mol/L) for 10 minutes. After 24 hours, cell viability was assessed by flow cytometry after propidium iodide staining. PAF rescues cells from αIgM-induced apoptosis. This is inhibited by both PAGPC (l) and Web n = 3; *P ≤ .05.
Journal of Allergy and Clinical Immunology  , DOI: ( /S (98) )
Copyright © 1998 Mosby, Inc. Terms and Conditions

5. Fig. 4
Low concentrations of PAGPC inhibits the ability of PAF to rescue Ramos cells from the effects of αIgM ligation. A, αIgM (2 μg/mL) inhibits the constitutive secretion of IgM antibodies by Ramos cells. Coincubation of Ramos cells with αIgM and PAF (10–7 mol/L) restores normal IgM secretion. Both PAGPC (l) (10–12 mol/L) and Web 2170 inhibit the action of PAF. B, Ramos cells were incubated with vehicle (0), PAGPC (l) (10–12 mol/L), or Web 2170 for 10 minutes, then washed extensively with PBS plus 1% BSA [signified by (:)]. BSA washing does not reverse the antagonistic effect of PAGPC, suggesting homologous desensitization of the PAF receptor. Both panels, n = 3; *P ≤ .05.
Journal of Allergy and Clinical Immunology  , DOI: ( /S (98) )
Copyright © 1998 Mosby, Inc. Terms and Conditions