Abstract: Objective To study the mechanism of platelet clearance caused by anti-CD36 antibodies in vivo. Methods The monoclonal antibody (mAb) 32-106 (IgG2a) was injected into the C57BL/6J female mice at a concentration of 2 mg/kg, and the platelet counts of these mice were detected at 0 h before injection, 0.5 h, 1 h, 2 h, 4 h, 6 h and 24 h after injection. The F (ab') 2 segment of 32-106 was obtained by digestion with pepsin and then injected into the C57BL/6J mice to analyze its clearance effect on CD36 (+) platelets. Subsequently, other subclasses of mAb 32-106 were generated and injected into the mice to analyze its clearance effect on CD36 (+) platelets. Results mAb 32-106 IgG2a significantly decreased the number of CD36 (+) platelets in C57BL/6J female mice (P<0.05) in vivo. However, the F (ab') ₂ segment of mAb 32-106 did not cause platelet clearance in female mice. The C57BL/6J female mice receiving 2 mg/kg of 32-106 IgG1 or 32-106 IgG3 also experienced decreased platelet counts. Compared with 32-106 IgG2a, the thrombocytopenia induced by 32-106 IgG3 or 32-106 IgG1 was not significant in mice. Conclusion The clearance of CD36 (+) platelets caused by anti-CD36 antibodies in vivo is in an Fc-dependent pathway, and anti-CD36 IgG2a antibody has a significant effect on CD36 (+) platelet clearance.

Key words: CD36, Monoclonal antibody, Platelet clearance, Fc-dependent