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Presence of HLA ‐ DR Molecules and HLA ‐ DRB 1 mRNA in Circulating CD 4 + T Cells
Author(s) -
Revenfeld A. L. S.,
Steffensen R.,
Pugholm L. H.,
Jørgensen M. M.,
Stensballe A.,
Varming K.
Publication year - 2016
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/sji.12462
Subject(s) - hla g , human leukocyte antigen , microbiology and biotechnology , context (archaeology) , hla dr , biology , antigen , immunology , paleontology
The human major histocompatibility complex class II isotype HLA ‐ DR is currently used as an activation marker for T cells. However, whether an endogenous protein expression or a molecular acquisition accounts for the presence of HLA ‐ DR on T cells remains undetermined and still controversial. To further characterize this phenomenon, we compared several aspects of the presence of the HLA ‐ DR protein to the presence of associated mRNA ( HLA ‐ DRB 1 ), focusing on human T cells from peripheral blood of healthy individuals. Using a flow cytometric approach, we determined that the HLA ‐ DR observed on CD 4 + T cells was almost exclusively cell surface‐associated, while for autologous CD 19 + B cells, the protein could be located in the plasma membrane as well as in the cytoplasm. Moreover, negligible expression levels of HLA ‐ DRB 1 were found in CD 4 + T cells, using an HLA ‐ DRB 1 allele‐specific qPCR assay. Finally, the presence of HLA ‐ DR was not confined to activated CD 4 + and CD 8 + T cells, as evaluated by the co‐expression of CD 25. The functional role of the HLA ‐ DR molecule on T cells remains enigmatic; however, this study presents evidence of fundamental differences for the presence of HLA ‐ DR on T cells from HLA ‐ DR in the context of antigen‐presenting cells, which is a well‐known phenomenon. Although an inducible endogenous protein expression cannot be excluded for the T cells, our findings suggest that a re‐evaluation of the HLA ‐ DR as a T cells activation marker is warranted.