Functional consequences of human lymphocyte cryopreservation: implications for subsequent interactions of cells with endothelium.

In order to understand human inflammatory diseases and to develop and assess new therapeutic strategies targeting leukocyte recruitment to tissue, it is necessary to study human lymphocyte interactions with endothelium. It is often not practical to carry out assays on fresh human samples and therefore cells may be cryopreserved and batched for later study. Furthermore, many forms of adoptive cell therapy use cryopreserved cells that are required to migrate to tissue after infusion in vivo. The consequences of cryopreservation on the adhesion and migration of leukocytes is not known leading us to study the effects of cryopreservation on lymphocyte phenotype, migration, and adhesion. Cryopreservation and subsequent thawing did not alter the proportion of retrieved T cell subsets. Overall levels of expression of β1 or β2 integrins were unaffected but marked changes were observed in other relevant receptors. Expression of CD69, a transmembrane protein that plays a critical role in lymphocyte egress from tissues and the chemokine receptor CXCR4, increased on thawed populations and levels of CD62L and CXCR3 were reduced on thawed cells but restored if cells were allowed to recover after thawing. These changes were associated with modulation of the ability of lymphocytes to migrate across cytokine-stimulated monolayers of endothelium toward recombinant CXCL11 and CXCL12. Thus cryopreservation and thawing of lymphocytes induces changes in their adhesive phenotype and modulates their ability to migrate across endothelial monolayers. These findings have implications for in vitro experimentation and for cell therapy in which cryopreserved cells are expected to migrate when reinfused into patients.