Background: The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.

The T-cell receptor (TCR) gamma polypeptide is expressed associated with CD3 (T3) on the surface of normal human peripheral blood lymphocytes. These cells function as non-MHC-restricted cytotoxic T lymphocytes (CTL)and thus may play an important role in host immune defence. The TCR gamma polypeptide occurs as a dimer in at least two molecular forms based on the absence or presence of disulphide linkage. These forms use TCR gamma polypeptides with strikingly different peptide backbone sizes.

Two clusters of overlapping cosmid clones comprising about 100 kilobases (kb) at the human T-cell antigen-receptor a/6 locus were isolated from a genomic library. The structure of the germ-line Vis1 variable gene segment was determined. V1al is located 8.5 kb downstream of the Val3.1 gene segment, and both V segments are arranged in the same transcriptional orientation. The Vd7.1 segment is located between V81 and the Li, J;, Cc, region (containing the diversity, joining, and constant gene segments). Thus, Vs and V% segments -are interspersed along the chromosome. The germ-line organization of the L 2, Jr,1, and Jr,2 segments was determined. Linkage of Cc, to the J. region was established by identification of J,, segments within 20 kb downstream of C8.The organization of the locus was also analyzed by fieldinversion gel electrophoresis. The unrearranged Vsl and D8, Jl, Cat regions are quite distant from each other, apparently separated by a minimum of 175-180 kb.In addition to T-cell antigen receptor (TCR) a43 (a heterodimer ofpolypeptides termed a and f3), a second TCR, 'y8, has recently been identified (1). Whereas TCR a,3 is expressed on the majority of peripheral blood T lymphocytes, TCR y5 is expressed on a small fraction of peripheral blood TYlymphocytes, as well as on some thymic T cells and dendritic epidermal cells. The-function of the lymphocytes that bear TCR y5 is unknown.The genes encoding the TCR a, /3, -y, and 8 polypeptides are all assembled from multiple gene segments that rearrange to form a functional gene during T-cell differentiation (1-3). The diversity of TCR a/3 is immense due to the use of large numbers of variable (V) and joining (J) segments, and in the case of TCR 3, diversity (D) segments as well. TCR y8 apparently displays a more limited repertoire of germ-line V and J elements but nevertheless displays extraordinary diversity at the V-J junction. This is due in part to the novel use of two Do elements that can be incorporated together into the junctional region (4-6).Whereas the TCR a, ,/, and ygenes are all unlinked, studies in mice (7), as well as preliminary studies in humans (8-10), indicate that the TCR 8 gene lies within the TCR a locus, upstream ofthe estimated 50-100J, segments and between V,, and J,,,. However, rearrangement at this locus appears to be highly regulated. Whereas TCR 8 genes rearrange early in thymic ontogeny, TCR a genes rearrange much later. Further, the utilization of V segments appears to be selective.For example, to date the human V.] segment has only been observed to be utilized in TCR y8 lymphocytes, whereas V. segments have not been found to be similarly utilized. The details of the organization of the TCR a/8 locus may shed light on the manner in which rearrangements at this locus are controlled. To better understand the structure of the germline elements that contribute to the diversity ofTCR 8, as well as the organization of these elements with respect to those of TCR a, we have undertaken an analysis of the germ-line organization of the T...

The human T cell receptor delta (TCR delta) gene encodes one component of the TCR gamma delta-CD3 complex found on subsets of peripheral blood and thymic T cells. Human TCR delta diversity was estimated by characterizing rearrangements in TCR gamma delta cell lines and determining the structures of complementary DNA clones representing functional and nonfunctional transcripts in these cell lines. One V delta segment and one J delta segment were identified in all functional transcripts, although a distinct J delta segment was identified in a truncated transcript. Further, one D delta element was identified, and evidence for the use of an additional D delta element was obtained. Thus human TCR delta genes appear to use a limited number of germline elements. However, the apparent use of two D delta elements in tandem coupled with imprecise joining and extensive incorporation of N nucleotides generates unprecedented variability in the junctional region.