Immunoglobulin G is present in a wide variety of soft tissue tumors and correlates well with proliferation markers and tumor grades.
BACKGROUND
The traditional view that immunoglobulin (Ig) is produced only by B lymphocytes has been challenged, because it has been demonstrated that Ig genes and proteins are expressed in epithelial cancer cells. However, whether Ig expression in nonlymphoid cells is limited to epithelial cells is unclear. Because sarcomas differ distinctly from carcinomas in their biologic and clinical features, the authors investigated the question of nonlymphoid IgG expression in soft tissue lesions.


METHODS
Immunohistochemistry, in situ hybridization, and polymerase chain reaction (PCR) were used to demonstrate IgG expression in 80 soft tissue lesions. The correlation between Ig expression and proliferation markers (proliferating cell nuclear antigen [PCNA], Ki-67, and cyclin D1) in sarcomas was investigated by immunohistochemical and statistical analyses.


RESULTS
Igkappa was identified in 97.4% of sarcomas and in 31.7% of benign lesions by immunohistochemistry. The difference was statistically significant (P < .01). Messenger RNA from the IgG1 heavy-chain constant region was also detected by in situ hybridization. Variable-diversity-joining recombination sequences of both heavy and light chains were obtained by PCR and sequencing. Moreover, the labeling index of PCNA, Ki-67, and cyclin D1 was much higher in sarcomas with high Igkappa expression than in sarcomas with low Igkappa expression (P < .01 for PCNA and cyclin D1; P < .001 for Ki-67). There were more grade 3 sarcomas with high Igkappa expression compared with grade 1 and 2 sarcomas (P < .05).


CONCLUSIONS
IgG was identified in a wide variety of soft tissue tumors and correlated well with proliferation markers and tumor grades. IgG may be a useful marker for cell proliferation in sarcomas.
Chen
Zhengshan
Z
Department of Pathology, Shantou University Medical College, Shantou, China.
Huang
Xinrui
X
Ye
Juxiang
J
Pan
Peng
P
Cao
Qi
Q
Yang
Baokai
B
Li
Zhuo
Z
Su
Meng
M
Huang
Chen
C
Gu
Jiang
J
D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000378:metabolism; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007147:Immunoglobulin Light Chains / Q000378:metabolism; D007142:Immunoglobulin gamma-Chains / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008969:Molecular Sequence Data; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012509:Sarcoma / Q000378:metabolism; D012983:Soft Tissue Neoplasms / Q000378:metabolism* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D014408:Biomarkers, Tumor; D007074:Immunoglobulin G; D007147:Immunoglobulin Light Chains; D007142:Immunoglobulin gamma-Chains; D019394:Ki-67 Antigen; D018809:Proliferating Cell Nuclear Antigen; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1