RESUMEN
Previous studies have shown that occupational lead (Pb) exposure might influence human T-lymphocyte function, including such as changes in T-cell receptor (TCR) Vß and Vγ repertoire and in expression of the TCRζ gene. Thus, the study here further investigated expression of TCRζ-related factors and the FcεRIγ gene (whose product has a functional role complementary to the TCRζ chain) and the Elf-1 gene whose product is involved in regulation of TCR expression. Quantitative real-time RT-PCR was used to measure expression of TCRζ, FcεRIγ, and Elf-1 genes in peripheral blood mononuclear cells (PBMC) isolated from 17 Pb-exposed workers. Samples were collected before and after the workers had undergone chelation therapy regimens. Twenty-three healthy individuals served as controls. The results showed that TCRζ, FcεRIγ, and Elf-1 gene expression in Pb-exposed workers before chelation therapy was significantly lower than in PBMC from healthy individuals. After chelation therapy, expression of TCRζ appeared to trend toward normal levels; in comparison, lower expressions of FcεRIγ and Elf-1 persisted. In conclusion, the previously-documented impairment of T-lymphocyte functions and T- lymphocyte-mediated immune responses seen previously in response to occupational Pb exposure might be attributable, in part, to effects on TCR signaling pathways - including those related to TCRζ and FcεRIγ - and to any down-regulation of membrane TCRζ expression/activity that might be associated with Pb-induced effects on Elf-1 expression.
Asunto(s)
Terapia por Quelación , Efrina-A2/metabolismo , Intoxicación por Plomo/inmunología , Receptores de Antígenos de Linfocitos T/genética , Receptores de IgE/metabolismo , Linfocitos T/inmunología , Adulto , Regulación hacia Abajo/efectos de los fármacos , Ácido Edético/administración & dosificación , Efrina-A2/genética , Femenino , Humanos , Intoxicación por Plomo/terapia , Masculino , Persona de Mediana Edad , Exposición Profesional/efectos adversos , Receptores de Antígenos de Linfocitos T/metabolismo , Receptores de IgE/genética , Linfocitos T/efectos de los fármacos , Adulto JovenRESUMEN
Influence of zinc supplementation (30 and 45 mg kg-1, orally once for 5 days) during chelation of lead (0.3 mmol kg-1, chelating agent, i.p., once for 5 days) on some selected variables of the immune system was investigated in male rats. Treatment with CaNa2EDTA either alone or in combination with zinc (30 mg kg-1) produced a significant recovery in lead induced alteration in primary antibody forming cells to T-dependent antigen and the delayed-type hypersensitivity response to bovine albumin. However, biologically significant recovery was observed only with zinc at a dose of 45 mg kg-1. It is assumed that zinc depletion during lead exposure and chelation treatment lead to harmful effects on cellular proliferation by inhibiting DNA synthesis and various enzymes during mitosis. The zinc supplementation fulfills this requirement during proliferation and clonal expansion of immunocompetent cells augmenting the immune system.