PubMed · 10337383
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L G Israels, E D Israels. 1999. Lymphocytes.. https://pubmed.ncbi.nlm.nih.gov/10337383/
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CCR6 is the only known receptor for the chemokine macrophage-inflammatory protein (MIP)-3alpha/CC chemokine ligand (CCL)20. We have shown previously that CCR6 is expressed on peripheral blood B cells, but CCR6 activity on these cells is low in in vitro assays. We report that MIP-3alpha/CCL20-induced calcium flux and chemotaxis can be enhanced significantly on peripheral blood and tonsillar B cells after activation by cross-linking surface Ag receptors. Of particular interest is the fact that the enhanced activity on B cells was not associated with an increase in CCR6 expression as assessed by levels of receptor mRNA, surface staining, or MIP-3alpha/CCL20 binding sites, or by a change in the affinity of the receptor for ligand. These data convincingly demonstrate that responses to a chemokine can be regulated solely by changes in the downstream pathways for signal transduction resulting from Ag receptor activation, and establish CCR6 as an efficacious receptor on human B cells.
Protective immunity depends upon the capability of the immune system to properly adapt the response to the nature of an infectious agent. CD4(+) Th cells are implicated in this orchestration by secreting a polarized pattern of cytokines. Although Th2 development in animal models and in human cells in vitro to a large extent depends on IL-4, the nature of the cells that provide the initial IL-4 in vivo is still elusive. In this report, we describe the anatomical localization as well as the identity of IL-4-producing cells in human tonsil, a representative secondary lymphoid organ. We demonstrate that IL-4 production is a normal and intrinsic feature of germinal center (GC) B cells. We also show that expression of IL-4 is highly confined to the GCs, in which the B cells constitute the prevalent cellular source. Furthermore, immunofluorescence analysis of colon mucosa reveals a strikingly similar pattern of IL-4-expressing cells compared with tonsils, demonstrating that IL-4 production from GC B cells is not a unique feature of the upper respiratory tract. Our results show that GCs provide the most appropriate microenvironment for IL-4-dependent Th2 polarization in vivo and imply a critical role for GC B cells in this differentiation process.
OBJECTIVE: We tried to estimate whether immunological changes are present in neonates born to mothers who had been suffering from pre-eclampsia. STUDY DESIGN: Eighteen neonates born to mothers with severe pre-eclampsia (between 35 and 40 weeks of gestation) and 20 full-term healthy newborns (between 38 and 40 weeks of gestation) were included in the study. The lymphocytes were isolated from umbilical cord blood. The specific lymphocyte antigens were determined using direct staining with monoclonal antibodies and analysed by flow-cytometry. RESULTS: We observed that neonates born to pre-eclamptic mothers had decreased percentage of T CD 3(+), CD 4(+) and T CD 8(+)28(+) (cytotoxic) lymphocytes and increased percentage CD 3(-)16/56(+) cells and CD 8(+)28(-) (suppressor) lymphocytes in comparison with newborns of healthy women. Furthermore, we found decreased CD 4: CD 8 lymphocyte ratio in the study group in comparison with the control group. We also observed that the percentage of CD 19(+)5(+), CD 4(+)8(+), CD 19(+)40(+) and CD 3(+)40L(+) lymphocytes did not differ in both studied groups. The percentage of CD 4(+)45RO(+), CD 8(+)45RO(+) memory cells was higher in neonates born to pre-eclamptic mothers when compared to controls. Moreover, the expression of CD 25 molecule was higher on T CD 8(+) and B CD 19(+) lymphocytes of neonates of pre-eclamptic mothers. CONCLUSION: The alterations in the immunological parameters of neonates born to pre-eclamptic mothers can be associated with the maternal disease.