CD23 Expression in Activated Human T Cells Is Enhanced by lnterleukin-7

Abstract

Despite evidence for the expression of the low-affinity Fc receptor for IgE (FcεRII/CD23) in several pathological conditions, the role played by CD23 in normal human T cells is still unclear. We studied the effect of a stomal-derived cytokine, interleukin (IL-7), on the expression of CD23 in human T cells stimulated with 10 μg/ml phytohemagglutinin (PHA). The results demonstrate that IL-7 did not induce CD23 expression in the resting T cells. However, PHA-induced CD23 expression was enhanced by costimulation with IL-7 (1,000 U/ml). Cytofluorometric analysis revealed that CD23 expression in activated T cells was enhanced by the addition of IL-7 (from 2% to 18%). It was also observed that the effect of IL-7 on CD23 expression is exclusively on CD4+ T cells. The enhanced expression of CD23 was blocked by an anti-IL-7 monoclonal antibody (mAb), but not by IL-2 and IL-4 mAbs. This suggests that IL-7 is a potent regulatory cytokine capable of acting independently of IL-2 and IL-4 in the expression of CD23. Northern blot analysis showed an increase in CD23 mRNA when activated T cells were cultured in the presence of IL-7. A significant increase in receptor numbers on activated T cells was detected by Scatchard analysis when IL-7 was added to the cell cultures. The induction of CD23 expression by IL-1, 1L-3, IL-4, IL-5, IL-6, interferon-8 and OKT3 on PHA-activated T cells was not of the same magnitude as observed in the presence of IL-7. These results demonstrate a selective induction of CD23 expression on activated human T cells cultured in the presence of IL-7. These data indicate that the stromal-derived growth factor points to an important role of CD23 in the regulatory network of the immune response.

Interleukin 7 and sCD23 Synergize in the Induction of Human T Cell Activation in HIV-1-Infected Subjects

“…An increased proliferative response to IL-7 and sCD23 was observed in CD4+ and CD8+ T cell subsets of HI V-l-seropositive compared to HI V-l-seronegative sub jects. This is in contrast to previous data showing in HIV-Iseronegative subjects an increase in CD23 receptors by IL-7 solely in CD4+ T cells [29], An explanation for this dis crepancy may be found in the fact that virus infection in duces a massive preactivation of CD4+ cells, rendering the cells more sensitive to the subsequent proliferative effects of IL-7 andsCD23. Indeed, an increased expression of these receptors (IL-7R and CD23) on the cell surface of CD4+ and CD8+ T cells o f HIV-l-seropositive subjects has been reported [26,31].…”

“…Increased sCD23 in serum and synovial fluid in rheu matoid arthritis patients has been demonstrated [29], rais ing the question of the direct role o f sC'D23 in other dis eases. It has been previously reported that sCD23 is in creased in HI V-l infection [31][32][33][34], The fact that sCD23 has been reported to costimulate IFN-y production raises the possibility that sCD23 may play a pivotal role in the control of the immune response.…”

“…Moreover, the receptors for IL-7 and CD23 have been found to be present lymphoid cells of HI V-l-infected subjects and on mitogen-stimulated T cells [25,26,[31][32][33][34]. It was suggested that the expression of these receptors correlates with the ability of stimulated T lympho cytes to proliferate in response to cytokines [25,29,31,[35][36][37]. Phenotypic analysis showed that IL-7 primarily affects the proliferation and cytotoxic activity of CD8+ T cells in HI V-l infection [28].…”

A new role for interleukin‐7 in the induction of LFA‐1 and VLA‐4 adhesion molecules in Phorbol 12myristate 13acetate activated CD4+CD23+ T‐cell subset

“…Purified T-cell fractions were set up in culture at 0.5 X 10%iL with I ng/mL of Phorbol-'-Myristate-'W-etate (PMA) plus ionomycin (Ca^) (O.I25mg/mL) for 3 days with or without lL-7 (10(K)U/mL) added at the onset of culture. This appears to be the best time and concentration to be used as previously reported [24]. Cells were then recovered and expanded for 4 days with IL-2 (60 U/mL).…”

“…Recently, we have reported an increase of CD23 mRNA and CD23 receptor numbers, when activated T cells were cultured in the presence of IL-7. It appears that lL-7 acts by a stabilizing effect on Ihe transcript [24].…”