MC at 1/μL maximally inhibit platelet-induced IgG antidonor antibody titers. Titrations of BALB/c MC were added to stock platelets from anti-AsGm1–treated SCID mice and transfused into CBA recipients weekly. Control transfusions with 10⁸ BALB/c platelets or 10⁵ BALB/c MC are shown. The data is expressed as the mean ± standard deviation (SD) of week 8 titers from 10 recipient CBA mice.