Perhaps a more popular theory is that the immunosuppressive effects of immunoglobulin therapy are mediated through IgG's Fc glycosylation. By binding to receptors on antigen presenting cells, IVIG can increase the expression of the inhibitory Fc receptor , FcgRIIB and shorten the half-life of auto-reactive antibodies.    The ability of immunoglobulin therapy to suppress pathogenic immune responses by this mechanism is dependent on the presence of a sialylated glycan at position CH2- of IgG.  Specifically, de-sialylated preparations of immunoglobulin lose their therapeutic activity and the anti-inflammatory effects of IVIG can be recapitulated by administration of recombinant sialylated IgG1 Fc. 
The table below is based on the pooled safety data on all LEMTRADA 12 mg-treated patients during all available follow up in clinical trials. Adverse reactions occurring in ≥% of patients are listed by Medical Dictionary for Regulatory Activities (MedDRA) System Organ Class (SOC) and Preferred Term (PT). Frequencies are defined according to the following convention: very common (≥ 1/10); common (≥ 1/100 to < 1/10); uncommon (≥ 1/1,000 to < 1/100); Not known (cannot be estimated from the available data). Within each frequency grouping, adverse reactions have been presented in order of decreasing seriousness.
Ruiz-Delgado et al (2011) stated that thrombocytopenia ensuing during acute graft-versus-host disease (GVHD) is multi-factorial and may significantly compromise the prognosis of the patient; non-immune persistent thrombocytopenia has been considered as an adverse prognostic factor in GVHD. These investigators described the case of a 10-year old girl who developed steroid-refractory thrombocytopenia and who responded promptly to the subcutaneous delivery of romiplostin. The authors noted that to the best of their knowledge, this is the first description of the usefulness of the peptibody in the setting of GVHD. However, UpToDate reviews on "Overview of immunosuppressive agents used for prevention and treatment of graft-versus-host disease" (Chao, 2012a),"Treatment of chronic graft-versus-host disease" (Chao, 2012b), and "Treatment of acute graft-versus-host disease: Clinical trials" (Chao, 2012c) do not mention the use of romiplostim as a therapeutic option.