Myeloma cells are highly sensitive to the granule exocytosis pathway mediated by WT1-specific cytotoxic T lymphocytes.
OBJECTIVE
Because WT1 is a universal tumor antigen, we examined the sensitivity of myeloma cells to WT1-specific cytotoxic T lymphocyte (CTL)-mediated cytotoxicity.


METHODS
WT1 expression in hematologic malignant cells was examined by quantitative reverse transcription-polymerase chain reaction. The cytotoxicity of a WT1-specific CTL clone against hematologic malignant cells, including myeloma cells, was examined by standard chromium-51 release assays. The extent of membrane damage induced by purified perforin was examined. Induction of WT1-specific CTLs from the patients with multiple myeloma (MM) was attempted, and we examined their function against myeloma cells.


RESULTS
The expression levels of WT1 mRNA in myeloma and lymphoma cells were significantly lower than that in acute leukemia cells. Although the WT1 expression levels in myeloma and lymphoma cells were almost same, only myeloma cells were lysed efficiently by WT1-specific CTLs in a HLA-restricted manner. The amounts of interferon-gamma produced by WT1-specific CTLs in response to stimulation with myeloma cells and with lymphoma cells were almost the same, suggesting that WT1 protein is processed and expressed in the context of HLA class I molecules similarly on both myeloma and lymphoma cells. The extent of membrane damage induced by purified perforin appeared to be significantly higher in myeloma cells than in lymphoma cells. WT1-specific CTLs appeared to be present in patients with MM.


CONCLUSIONS
The present study has shown that susceptibility of membranes to perforin is an important factor determining the sensitivity of target cells to CTL-mediated cytotoxicity and that WT1 is an ideal target antigen for cellular immunotherapy of MM.
Azuma
Taichi
T
First Department of Internal Medicine, Ehime University School of Medicine, Ehime, Japan.
Otsuki
Takemi
T
Kuzushima
Kiyotaka
K
Froelich
Christopher J
CJ
Fujita
Shigeru
S
Yasukawa
Masaki
M
D000951:Antigens, Neoplasm / Q000737:chemistry; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002857:Chromium / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005089:Exocytosis; D005434:Flow Cytometry; D005805:Genes, MHC Class I; D006801:Humans; D007167:Immunotherapy; D007371:Interferon-gamma / Q000378:metabolism; D008223:Lymphoma / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism; D009101:Multiple Myeloma / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism*; D016896:Treatment Outcome; D025721:WT1 Proteins / Q000096:biosynthesis*
D000951:Antigens, Neoplasm; D018942:Macrolides; D008562:Membrane Glycoproteins; D010455:Peptides; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D025721:WT1 Proteins; D002857:Chromium; D054353:Perforin; D004533:Egtazic Acid; C036978:concanamycin A; D007371:Interferon-gamma; D002118:Calcium