Human TLR1 plays an important role in host defense against Mycobacterium tuberculosis. Our aim was to analyze the association of the loss of TLR1 surface expression and TLR1 SNPs with susceptibility to TB. TLR1neg and TLR1pos cells from healthy individuals were identified by flow cytometry and compared by sequencing. TLR1 expression was measured using quantitative real-time PCR and immunoblotting. TLR1 SNP analyses of healthy individuals and TB patients from EU-C and Ghana were performed, and association of the TLR1 genotypes with increased risk of developing TB was statistically evaluated. Lack of TLR1 surface expression accompanied by impaired function was strongly associated with TLR1 SNP G743A. Genotyping of EU-C controls and TB patients revealed an association of TLR1 743A/1805G alleles [OR 2.37 (95% CI 1.13, 4.93), P=0.0219; OR 2.74 (95% CI 1.26, 6.05), P=0.0059] as well as TLR1neg 743AA/1805GG versus TLR1pos genotypes 743AG/1805TG [OR 4.98 (95% CI 1.64, 15.15), P=0.0034; OR 5.70 (95% CI 1.69, 20.35), P=0.0015] and 743AG + GG/1805TG + TT [OR 3.54 (95% CI 1.29, 9.90), P=0.0086; OR 4.17 (95% CI 1.52, 11.67), P=0.0025] with increased susceptibility to TB. No association of G743A with TB was found in Ghana as a result of a low frequency of genotype 743AA. Our data gain new insights in the role of TLR1 in M. tuberculosis defense and provide the first evidence that TLR1 variants are associated with susceptibility to TB in a low-incidence country.

Cholesterol is known to play an important role in stabilizing particular cellular membrane structures, so-called lipid or membrane rafts. For several viruses, a dependence on cholesterol for virus entry and/or morphogenesis has been shown. Using flow cytometry and fluorescence microscopy, we demonstrate that infection of cells by canine distemper virus (CDV) was not impaired after cellular cholesterol had been depleted by the drug methyl-␤-cyclodextrin. This effect was independent of the multiplicity of infection and the cellular receptor used for infection. However, cholesterol depletion of the viral envelope significantly reduced CDV infectivity. Replenishment by addition of exogenous cholesterol restored infectivity up to 80%. Thus, we conclude that CDV entry is dependent on cholesterol in the viral envelope. Furthermore, reduced syncytium formation was observed when the cells were cholesterol depleted during the course of the infection. This may be related to the observation that CDV envelope proteins H and F partitioned into cellular detergent-resistant membranes. Therefore, a role for lipid rafts during virus assembly and release as well is suggested.

Dose escalation occurred frequently, and in one third of patients the dose was at least doubled. Dose escalations were associated with substantial increases in direct drug costs. Dose escalation of adalimumab can severely affect both the health care system and the drug budget of the physician. It needs to be considered that other biologic medications may constitute a more cost-effective alternative.