*Purpose: Heparanase (Hpse) is the sole heparan sulfate (HS) degrading enzyme regulating multiple biological activities that enhance immune cell migration, blood vessel growth and cell proliferation. Our preliminary studies show that HS is a plasma biomarker of acute cellular allograft rejection and hypothesize , indicating that HS degradation by Hpse is critical of for immune cell infiltration and graft rejection. Hpse expression by NK cells and monocytes/microphages are well described. However, e. Expression of Hpse by CD4+ T -cells , however, is poorly understood.

*Methods: Wild-type and Hpse KO mice were used to provide splenic and peripheral blood mononuclear cells for quantitative PCR to investigate Hpse expression by CD4+ T -cells in cultures conditioning with/without HS-containing Matrigel. A BALB/c-to-C57BL/6B6 skin graft model was used to provide skin allograft samples for immunofluorescent (IF) microscopy to examine Hpse+ CD4+ T -cells.

*Results: qPCR showed that splenocytes from naïve B6 mice expressed high levels of Hpse while splenocytes derived from Hpse-KO mice had no Hpse expression. Nnaive CD4+ T -cells isolated through EasySep magnetic column (negative selection) expressed low levels of Hpse before cell cultures (p<0.01 vs. that of splenocytes). Hpse expression farther reduced following T-cell cultures with CD3/CD28 stimulation, indicating that Hpse expression is negatively influenced by TCR activation. CD4+ T -cells cultured in wells containing Matrigel exhibited a 19-fold increase and a 14-fold increase in Hpse expression in 48 and 72 hours, respectively (p<0.01; p<0.01 vs. that of naïve CD4+ T -cells). Interestingly, Hpse expression fartherwas reduced following T-cell cultures with CD3/CD28 stimulation, indicating that Hpse expression is negatively influenced by TCR activation. IF microscopy demonstrated that Hpse is expressed by CD11b+ macrophages and CD4+ T-cells among the infiltrates presented in the skin grafts.

*Conclusions: Our data demonstrate: (1) Hpse expression by CD4+ T -cells is conditional, depending on the presence of HS containing Matrigel containing HS; (2) General CD4+ T cell activation TCR activation of CD4 T-cells by CD3/CD28 ligation inhibits Hpse expression, indicating that Hpse expression is delicately controlled by factors relating to T-cells’ bioactivities.

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