In a comparison of memory B cells, IgM memory B cells and antibody responses to vaccination it was found that there was no difference in antibody responses between controls and those with splenectomy for spherocytosis [17] but decreased IgM responses and reduced IgM memory B cells in those with splenectomy for Idiopathic Thrombocytopenic Purpura (ITP). The gene discussed is CD40LG; the disease is autoimmune thrombocytopenic purpura.