Human T-lymphotropic virus type I (HTLV-I) is the causative agent in
adult T-cell leukemia and
HTLV-I associated myelopathy. Some other diseases such as
uveitis,
chronic thyroiditis, Sjögren syndrome,
arthritis,
acute myeloid leukemia and
myelodysplastic syndrome may be also associated with HTLV-I. Several case reports have suggested the possible combination of
idiopathic thrombocytopenic purpura (
ITP) and
HTLV-I infection. In these studies and from our current report, we found 17 patients (22.1%) with
HTLV-I infection among 77
ITP patients. The prevalence of
HTLV-I infection among
ITP patients was higher than that of healthy volunteers (5 approximately 10%). The
ITP patients with
HTLV-I infection were older than the patients without
HTLV-I infection, and the
ITP patients with
HTLV-I infection had poor response to
prednisolone therapy. Among 17
ITP patients with
HTLV-I infection, 9 patients received
prednisolone therapy. Although most patients had transient increase of platelet counts, only two of them had partial responses (PR) at the last observation date. Five patients underwent
splenectomy, and four of them had complete responses (CR) and the remaining patient had a (PR). Four patients received eradication of Helicobactor pylori (H. pylori)
infection, and all patients had CRs. Therefore, the
ITP patients with
HTLV-I infection should receive eradication
therapy in the case of H. pylori
infection as the first step of
therapy and the
splenectomy should be considered, if there is no response to conventional
therapy. Human immunodeficiency virus (HIV) causes
thrombocytopenia in 10% of patients with active HIV disease. The etiologies of HIV
thrombocytopenia are considered as follows, the escalated destruction of platelets by the immune system, damage to megakaryocytes by
HIV infection and the inhibition of thrombopoiesis by some anti-viral drugs. In the case of
ITP patients with
HTLV-I infection, the main etiology may be the increased destruction of platelets by immune system. The proviral load and the integration pattern of HTLV-I should be examined to clarify the stage of
HTLV-I infection. The possibility of
infection of the megakaryocytes by HTLV-I should be also examined for etiological approach.