Schematic representations of three types of WC1 molecules. The WC1 genes corresponding to the schematics are indicated. WC1+ γδ T cells were defined based on mAb reactivity as WC1.1+, WC1.2+, and WC1.3+ wherein the WC1.3+ population is a subpopulation of WC1.1+ cells . According to their domain 1 sequence similarities with bovine archetypal WC1.1 (WC1-3), archetypal WC1.2 (WC1-4) or swine WC1 domain 1 sequences, WC1 genes were further classified into groups: WC1.1-like, WC1.2-like, unique, and swine-like. Among WC1.1-like WC1 genes, WC1-8 (nd2) represents the gene product which reacts with the anti-WC1.3 mAb (Chuang and Baldwin, unpublished data) and which is different from the WC1.3 gene sequence reported by Wijngaard et al. . No WC1 genes have the SRCR domain 1 sequences reported by Wijngaard et al. ; instead, the most similar sequence is that of SRCR domain 6 of WC1-4 and WC1-9, and we thus suggest part of the published WC1.3 sequence is erroneous.