Identification of an overexpressed gene, HSPA4L, the product of which can provoke prevalent humoral immune responses in leukemia patients.
OBJECTIVE
To identify leukemia-associated antigens, we applied the serological identification of antigens by the recombinant expression cloning (SEREX) method to a chronic myelogenous leukemia (CML) patient who achieved a cytogenetic response to interferon-alpha.


METHODS
Immunoscreening of the cDNA library was performed with sera from a CML patient. Two isolated antigens were used to evaluate the expression pattern using Northern blot analysis and quantitative reverse transcriptase polymerase chain reaction. Western blotting and enzyme-linked immunosorbent assay were also performed for serological analysis.


RESULTS
We identified 14 positive clones, representing five different antigens. Of these, two genes were further validated. One (clone 70) was the human polyribonucleotide nucleotidyltransferase 1 (PNPT1), which is the type I interferon (alpha/beta-responsive gene). The mRNA of clone 70 was ubiquitously expressed in normal human tissues. The other gene (clone 57) was the heat shock 70-kDa protein 4-like (HSPA4L), which is a member of the heat shock protein 110 family, whose mRNA is strongly expressed in normal human testis and overexpressed in leukemia cells. Seroactivity against HSPA4L was detected in 6 of 9 acute myeloid leukemia patients, 4 of 10 acute lymphoblastic leukemia patients, 9 of 11 CML patients, and none of 10 healthy volunteers. Leukemia patients had higher titer of the antibodies against the protein than healthy volunteers.


CONCLUSIONS
These results suggest that HSPA4L, a member of heat shock protein, is highly expressed by leukemia cells, and elicit humoral immune responses in leukemia patients, and it might be a potential target for antileukemia therapy and an antigen-specific immunotherapy for leukemia.
Takahashi
Hidenobu
H
Division of Hematology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Furukawa
Tatsuo
T
Yano
Toshio
T
Sato
Naoko
N
Takizawa
Jun
J
Kurasaki
Tori
T
Abe
Takashi
T
Narita
Miwako
M
Masuko
Masayoshi
M
Koyama
Satoru
S
Toba
Ken
K
Takahashi
Masuhiro
M
Aizawa
Yoshifusa
Y
D000917:Antibody Formation; D002460:Cell Line; D050957:HSP110 Heat-Shock Proteins / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007938:Leukemia / Q000276:immunology*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000276:immunology; D015470:Leukemia, Myeloid, Acute / Q000276:immunology; D016133:Polymerase Chain Reaction; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000276:immunology
D050957:HSP110 Heat-Shock Proteins; C121993:HSPA4 protein, human