Surface thiols of human lymphocytes and their changes after in vitro and in vivo activation

Abstract

Cellular thiols have long been known to play a role in cell activation and proliferation; however, the differential expression of surface thiols on the lymphoid subsets had not been described. Neither was it known whether alteration of surface thiols occurs after exposure to mitogens or infectious agents. Herein, an impermeant thiol-specific fluorescent probe was employed for flow cytometric analysis of surface thiols. Quantification of surface thiols on resting lymphocytes revealed that some subsets expressed different concentrations of surface thiols (CD19+ > CD8+ > CD4+). Furthermore, surface thiols increased on all subsets by 8 h after mitogenic activation. This increase was blocked by cycloheximide or monensin but not by actinomycin D or inhibition of glutathione synthesis by buthionine sulfoximine. In addition, bacitracin, an inhibitor of protein disulfide isomerase, inhibited the increase in surface thiols and DNA synthesis. Lymphocytes from HIV-infected individuals displayed increased surface thiols on CD19+ and CD4+ cells but not CD8+ cells. Although cellular thiols in general have been believed to play a role in protection against oxidants, signaling associated with cell growth, and apoptosis, there is now evidence that changes in exofacial thiols appear to be involved in some of these critical cell reactivities. Thus, quantitative and possibly qualitative differences in surface thiols correlate with membrane differences between lymphoid subsets and with their differential sensitivities to oxidative stress, which suggests that the mechanisms by which surface thiols are maintained and modified after activation are important cellular functions that need to be further evaluated.

Naturally occurring regulatory T cells show reduced sensitivity toward oxidative stress–induced cell death

“…21,22 Several mechanisms contribute to cellular protection against oxidative stress, one being proteins containing free thiol groups expressed at various levels on lymphoid subsets. 23,24 The amount of thiols per cell was significantly greater in the Treg population, which is similar to the observation made in oxidative stress-resistant CD56 bright NK cells ( Figure 2B). 25 Tregs showed significantly lower basal intracellular oxidation levels when freshly isolated and upon H 2 O 2 treatment, indicating a greater antioxidative capacity ( Figure 2C).…”

Glycosaminoglycans and Protein Disulfide Isomerase-Mediated Reduction of HIV Env

“…Our work also shows that inhibition of disulfide bond reduction by surface reductases can be achieved by compounds that interact with the substrate and not solely with the catalyst, as achieved previously (Mandel et al, 1993). This offers new perspectives in the therapeutic regulation of a process required for activation of various exofacial proteins involved in physiological (Lawrence et al, 1996;Sahaf et al, 2003) and pathological events (Ryser et al, 1991;Droge, 2002). …”

Ncf1-Associated Reduced Oxidative Burst Promotes IL-33R+ T Cell-Mediated Adjuvant-Free Arthritis in Mice

“…T cells are very much dependent on the oxidation status of their extracellular environment. Alterations of the membrane redox situation of T cells mediated by ROS determine T cell responsiveness and activation such as, for example, through the oxidation-sensitive T cell surface molecule linker for activation of T cells that can lower the TCR signaling after oxidation (34).…”