Role of Macrophage Migration Inhibitory Factor (MIF) in Hodgkin Lymphoma
MJ Kluk, KM Hoyt, C Bifulco. Massachusetts General Hospital, Boston, MA; Yale New Haven Hospital, New Haven, CT
Background: Macrophage migration inhibitory factor (MIF), a 12.5kDa protein discovered in 1966, is a soluble factor secreted by lymphocytes that inhibits macrophage migration. Subsequent studies revealed that various human cell types express MIF and its cell surface receptor, CD74. In addition, MIF promoter polymorphisms are associated with increased MIF expression and correlate with susceptibility and severity of human autoimmune disorders and prostate cancer. We investigated the prevalence of MIF promoter polymorphisms in patients with Hodgkin lymphoma and tested the effects of MIF on the proliferation and migration of a Hodgkin lymphoma cell line.
Design: The-173 G to C single nucleotide polymorphism (SNP) in the MIF promoter was characterized by sequencing genomic DNA from 60 cases of Hodgkin lymphoma and 97 control cases. Expression of MIF and CD74 was tested by immunohistochemistry of formalin fixed, paraffin embedded tissue samples from Hodgkin lymphoma patients and in the KM-H2 human Hodgkin lymphoma cell line. Lastly, KM-H2 cells were treated with various concentrations of MIF, ISO-1 (MIF Inhibitor), sphingosine-1-phosphate or complete growth medium (10% FBS) to determine the effects, if any, on proliferation and migration.
Results: Genotyping of the -173 SNP in 60 Hodgkin patients revealed 60% (36/60) G/G, 33% (20/60) G/C and 7% (4/60) C/C. While in control cases there were 77% (75/97) G/G, 23% (22/97) G/C and 0% (0/97) C/C. Immunohistochemistry demonstrated staining for MIF and CD74 in the KM-H2 cell line and in both Hodgkin Reed-Sternberg cells and background lymphocytes in tissue samples from Hodgkin patients. Treatment of KM-H2 cells with various concentrations of MIF and/or ISO-1 made no significant difference in proliferation, as assessed by cell number, after 2 days of treatment in a variety of culture conditions. Interestingly, in cell migration assays, sphingosine-1-phosphate (5nM) was a potent chemoattractant for the KM-H2 cells, however, MIF and ISO-1 had no significant effect on migration alone or in combination with sphingosine-1-phosphate.
Conclusions: These results suggest an increase in the -173 C allele frequency in Hodgkin lymphoma patients compared to controls. In addition, both MIF and CD74 are expressed in tissue from Hodgkin lymphoma patients and in the KM-H2 Hodgkin lymphoma cells. However, further study is required to elucidate the role, if any, that MIF plays in regulating Hodgkin Reed-Sternberg cell proliferation and migration.
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 198, Wednesday Morning