ABSTRACT
P-glycoprotein (Pgp), the ABCB1 gene product, acts as an efflux pump that transports a large variety of substrates and is a mechanism of cell protection against xenobiotics. An increasing number of studies have shown that some ABCB1 polymorphisms may affect Pgp expression and activity, as well as affecting the development and susceptibility to diseases and pharmacological response. High activity of Pgp has been detected in systemic lupus erythematosus (SLE) patients. The C1236T, G2677T/A, and C3435T are the most commonly studied single nucleotide polymorphisms in the ABCB1 gene. Therefore, their frequencies were determined in Brazilian individuals with European ancestry (N = 143) and in SLE patients (N = 137). Genotyping was performed by PCR-RFLP analysis using specific primers followed by incubation with the appropriate restriction enzymes. The resulting DNA fragments were visualized on agarose or polyacrylamide gels. No statistically significant differences were observed in allelic and genotypic frequencies between SLE and healthy subjects (Fisher exact test). Nevertheless, the 2677A allelic frequency was lower in SLE patients with malar rash (0.007) compared with patients without this feature (0.04; P = 0.0054), while the frequency of this variant was higher in SLE patients with pleuritis (0.07) compared with patients without this feature (0.01; P = 0.0156). We suggest that although the ABCB1 polymorphisms do not directly interfere in SLE susceptibility, their evaluation, especially the 2677A allele, in other immunological processes may be interesting since they can interfere in clinical features of this disease.
Subject(s)
Adolescent , Adult , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Young Adult , Lupus Erythematosus, Systemic/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Polymorphism, Single Nucleotide/genetics , Black People , Case-Control Studies , White People , Gene Frequency , Genotype , Polymerase Chain Reaction , Young AdultABSTRACT
Bone marrow cells from adult BALB/c mice were cultured at 37-C, with 5% CO2 in air, in RPMI 1640 medium complemented with fetal serum. The addition of IL-3 (5% of WEHI-3-conditioned medium) or E. coli lipopolysaccharides (LPS, 50 µg/ml) to the cultures stimulated cell proliferation (1.29 and 1.22-fold, respectively, relative to control culture), whereas the simultaneous addition of the two factors reduced the number of cells recovered by 38% relative those from control cultures (which were around 2.83 x 10***5 cells for each 10***6 plated cells). The frequency of blasts and cells with surface Ig presented the same pattern of variation (o.07 and 0.02%, respectively, in control cultures). The inhibitory effect of IL-3+LPS on cell proliferation was evident from the first day of culture, but more apparent on day 3. Macrophage-colony stimulating factor (M-CSF, L929-conditioned medium) and LPS each given alone stimulated proliferation but reduced it when given together. In contrast, fetal liver cells were not affected by the simultaneous addition of IL-3 and LPS or by M-CSF and LPS. The mechanism of action of the cumulative effect of these two factors in unknown. Since crude cell-conditioned medium was used as the source of IL-3, it is possible that another factor present in this medium interacts with LPS to cause the inhibitory effect on cell proliferation