SPDL1 and Sepsis: It should be noted, however, that while the PD1-PD-L1 axis has been implicated in sepsis-associated immune suppression, (7, 13) and patients with septic shock displayed increased PD-1 and PD-L1 expression on circulating monocytes and CD4 + T lymphocytes, (43) the plasma levels of sPD-L1 are not necessarily functionally linked to immune suppression.