NCBI Summary:
This gene encodes a membrane glycoprotein of T lymphocytes that interacts with major histocompatibility complex class II antigenes and is also a receptor for the human immunodeficiency virus. This gene is expressed not only in T lymphocytes, but also in B cells, macrophages, and granulocytes. It is also expressed in specific regions of the brain. The protein functions to initiate or augment the early phase of T-cell activation, and may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system. Multiple alternatively spliced transcript variants encoding different isoforms have been identified in this gene. [provided by RefSeq, Aug 2010]
General function
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Cellular localization
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CD4(+)CD28(null) T lymphocyte frequency, a new marker of cardiovascular risk: relationship with polycystic ovary syndrome phenotypes. Moro F et al. (2012) To study the frequency of CD4(+)CD28(null) T cells, which are aggressive T lymphocytes associated with recurrent coronary instability and type 2 diabetes mellitus, in different polycystic ovary syndrome (PCOS) phenotypes and in age- and body mass index-matched healthy women. Retrospective cohort observational study. Unit of human reproductive pathophysiology, university hospital. A total of 167 PCOS patients and 102 control subjects. None. CD4(+)CD28(null) T cell frequency, high-sensitive C-reactive protein levels, and other glucose-metabolic parameters. CD4(+)CD28(null) frequency was significantly higher in all PCOS groups than in control subjects. CD4(+)CD28(null) frequency was significantly higher in nonhyperandrogenic phenotype (5.7%, range 3.2-7.1) than in phenotypes with hyperandrogenism (H) + oligoamenorrhea (O) + polycystic ovary (PCO) (3.5%, range 1-5.8), H + O (3%, range 1.8-4.7), and H + PCO (2.63%, range 1.2-4.1). The relative risk of non-H phenotype for PCOS women in the highest quartile for CD4(+)CD28(null) frequency compared with PCOS women with the lowest quartile was 3.2 (95% confidence interval 1.9-5.8). Cardiovascular risk evaluation should be performed in all PCOS phenotypes. In particular, we demonstrated that the non-H phenotype has potentially increased cardiovascular risk in terms of CD4(+)CD28(null) frequency.//////////////////