Human T cells expressing the gamma/delta T-cell receptor (TcR-1): C gamma 1- and C gamma 2-encoded forms of the receptor correlate with distinctive morphology, cytoskeletal organization, and growth characteristics.

ABSTRACT

BB3 and delta-TCS1 monoclonal antibodies identify two distinct nonoverlapping populations of T-cell receptor (TcR) gamma/delta (TcR-1)-positive cells, which express a disulfide-linked and a nondisulfide-linked form of TcR, respectively. BB3+ cells represented the majority of circulating TcR-1+ cells, but they were virtually undetectable in the thymus. On the other hand, delta-TCS1+ cells were largely predominant among TcR-1+ thymocytes but represented a minority in peripheral blood (PB). Similar distributions were observed by clonal analysis of thymocytes or PB TcR-1+ populations. The use of joining region (J)-specific probes indicated that BB3+ and delta-TCS1+ clones displayed different patterns of J rearrangement. Thus, the disulfide-linked form of TcR-1 (BB3+ clones) was associated with the expression of J segments upstream to the C gamma 1 gene segment, whereas the nondisulfide-linked form (delta-TCS1+ clones) was associated with the expression of J segments upstream to C gamma 2. delta-TCS1+ clones, in most instances, exhibited a growth pattern different from that of BB3+ or conventional TcR alpha/beta+ clones as they adhered promptly to surfaces, spread, and emitted long filopodia ending with adhesion plaques. Ultrastructural analyses showed, exclusively in delta-TCS1+ cells, nuclear deformations, uropod formation, and abundant cytoskeletal structures. In addition, immunofluorescence studies of this subset of TcR-1+ cells revealed the presence of abundant microtubules, intermediate filaments, and submembranous microfilaments. Thus, our findings suggest that delta-TCS1+ cells are capable of active motility.