Apoptosis of T lymphocytes in the spinal cord lesions in HTLV-I-associated myelopathy: a possible mechanism to control viral infection in the central nervous system.
Immunocytochemical staining of spinal cords from five autopsied patients with HAM/TSP was performed using the monoclonal antibody TIA-1, a marker of cytotoxic T lymphocytes (CTL). Many TIA-1+, CD8+ cells are distributed in active inflammatory lesions. The number of TIA-1+ cells is related to the amount of HTLV-I proviral DNA in situ. The protein TIA-1 has been associated with the induction of apoptosis in target cells. In active inflammatory lesions, we found cells undergoing apoptosis, most of them identified as helper-inducer CD45RO T lymphocytes, which were consistent with in vivo cellular tropism of HTLV-I in patients with HAM/TSP. These findings suggest that CTL-induced apoptosis of T lymphocytes may be one of the possible mechanisms which eliminate HTLV-I-infected cells from the central nervous system. In addition, many T lymphocytes in the inflammatory lesions expressed bcl-2 oncoprotein, suggesting that infiltrated T lymphocytes may be resistant to apoptosis. Expression of bcl-2 oncoprotein may explain the longstanding inflammatory process in the central nervous system of HAM/TSP.
Third Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Japan.
F
F
Umehara
A
A
Nakamura
S
S
Izumo
R
R
Kubota
S
S
Ijichi
N
N
Kashio
K
K
Hashimoto
K
K
Usuku
E
E
Sato
M
M
Osame
D000911:Antibodies, Monoclonal; D017209:Apoptosis; D004279:DNA, Viral / Q000032:analysis; D006801:Humans; D007167:Immunotherapy; D015493:Paraparesis, Tropical Spastic / Q000473:pathology* / Q000628:therapy*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013118:Spinal Cord Diseases / Q000473:pathology / Q000628:therapy*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000911:Antibodies, Monoclonal; D004279:DNA, Viral; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2