3B). Using PCR to isolate the complete cDNA of CLEC12B from PBMC, we found the mRNA of this molecule to be differentially spliced (Fig. 3C). Four different splice variants of CLEC12B were detected resulting from two independent differential splicing events. Splice variant A codes for a protein that shows the canonical lectin-like structure consisting of an intracellular domain, a transmembrane domain and a stalk domain encoded by one exon each followed by three exons coding for three CTLD. A differential

splicing event at the 3′-end of the second CTLD exon leads to an extension of this exon which contains a stop codon giving rise to a protein lacking the last of the three CTLD (variant B). A second differential splicing event does not join BGB324 the transmembrane coding exon to the 5′-end of the stalk exon but instead uses a potential splice site 8 bp further downstream in the stalk exon. This selleckchem causes the deletion of 8 bp of the mRNA resulting in a frame shift and the immediate stop of translation. The putative resulting proteins contain only the cytoplasmatic and transmembrane domains (variant C and D). Because these differential splicing events also give rise to truncated, potentially non-functional proteins, it was of interest not only to determine the overall expression

levels of CLEC12B but also to discriminate especially between putative functional and non-functional isoforms using different sets of primers. As shown in Figure 3D isoforms A and B of CLEC12B are not expressed by HUVEC, the myeloid–erythroid line K-562, the B-cell lines 721.221 and RPMI 8866, and the NK cell line NK-92. Low expression could be detected in DC, the monocytic lines U-937 and Mono-Mac-6 and the T-lymphocyte line Jurkat. The T-lymphocyte line CCRF-CEM expressed the highest levels of mRNA. In general, the majority of the transcripts detected in these cells contain the 8- bp deletion in the stalk exon probably rendering the translated product non-functional. Only CCRF-CEM cells express substantial levels of CLEC12B mRNA that probably code for a functional protein (Fig. 3D). Thus, it seems that CLEC12B RVX-208 and CLEC9A do not display

the myeloid-specific expression observed for CLEC-1, CLEC-2 and DECTIN-1 but are more broadly expressed in the myeloid as well as the lymphocyte lineage. The C-type lectin-like receptors CLEC-1, CLEC-2 and DECTIN-1 are known to be expressed in DC [14, 40, 41], and DECTIN-1 has been shown to be downregulated upon activation of DC [14, 42]. We therefore investigated the regulation of CLEC12B and CLEC9A in comparison with DECTIN-1, CLEC-1 and CLEC-2 in DC after treatment with various maturation stimuli. To this end, DC derived from CD34+ cord blood cells were treated with LPS, Zymosan A, anti-CD40 mAb cross-linked by F(ab’)2-fragments of goat anti-mouse IgG and INF-γ for 6 h, and mRNA levels were measured using real-time RT-PCR.