karen, it's a reference to my ITP treatments table found on this page:
bottools.com/Hal/ItpTypes.html
Quick summary, row:
1 . . those that respond to steroids
2 . . those that don't respond to IVIG (alone)
3 . . those that have a 4-5 week response to IVIG
4 . . those that respond about a week to IVIG
The four treatment response rows is based off of this study which claims there are exactly four ITP antibodies - and no more:
"Autoantibodies to Thrombopoietin and the Thrombopoietin Receptor in Patients with Immune Thrombocytopenia"
www.bloodjournal.org/content/128/22/2548?sso-checked=true
Also of note. The first two rows are platelet 'destruction' problems. The second two rows are platelet 'production' problems.