CD69 Expression On Activated Lymphocytes Is Stable In Streck's Cyto-Chex® BCT

By Jodi Alt, Ph.D

The purpose of this study was to determine if the activation marker, CD69, is preserved and stable in whole blood samples collected in Cyto-Chex® BCT. Previous studies have demonstrated CD marker stability of whole blood samples collected in Cyto-Chex BCT for up to 7 days when stored at room temperature (18-22°C). This data demonstrates stability of in vitro activated lymphocytes expressing CD69 for up to 7 days compared to activated lymphocyte samples maintained in K2EDTA. This allows for CD69 testing of whole blood in patient samples expressing CD69 due to a disease state, and flexibility for sample manipulation to activate cellular pathways involved in signaling and possible therapeutics at a later testing date.

CD69, also known as activation inducer molecule (AIM), early activation antigen 1 (EA-1), Leu-23, and MLR3, is a type II integral membrane protein with an extracellular c-type lectin domain. CD69 is not detectable on normal peripheral blood lymphocytes, but cell surface expression is upregulated in response to a wide variety of stimuli. Although CD69 null mice have no apparent developmental or T-cell function defects, these mice do display some degree of antitumor protection when challenged. Additionally, it has recently been elucidated that CD69 plays a pivotal role in the differentiation of the Th17 immune response via direct binding and inhibition of the Jak3/Stat5 transcription factor pathway. The Th17 immune response has been implicated in autoimmune and sensitivity reactions, including arthritis.

The ligand for CD69 has yet to be determined; however, CD69 expression is one of the earliest cellular changes noted in response to external stimuli and can be found on T, B, and NK cells. RNA expression of CD69 reaches its peak 3-6 hours post-stimulation with cell surface expression by 12 hours. After a slight drop at 24 hours, expression remains steady through 48 hours. This is in contrast to other activation markers, such as CD71 and HLA-DR, which are upregulated later in this process. Thus, the balance and regulation of CD69 expression with other extracellular signals is important in coordinating the regulation of the immune response.