T lymphocytes require two distinct signals for activation from antigen presenting cells . The first antigen-specific signal occurs when the T-cell receptor binds to antigenic peptides presented by major histocompatibility complex molecules. The second costimulatory signal occurs when CD28 and CTLA-4 on T cells bind to the CD80 (B7) and CD86 (B7-2 or B70) counter-receptors on antigen presenting cells . The costimulatory signal is essential for T-cell activation in the human and mouse immune systems, since its absence results in clonal inactivation or T-cell anergy .
We sequenced the rabbit T-cell receptor gamma and delta chain genes by polymerase chain reaction (PCR)amplification of the gene segments with human counterpart-specific primers, followed by gene walking, using cassette-ligation-mediated PCR [(CLM-PCR) ]. This procedure is simple and reliable for characterizing genes for which homologous sequence data are available. Here, we determined the nucleotide sequence of the rabbit genes for the costimulatory molecules, CD28, CTLA-4, CD80, and CD86 by this procedure.
We amplified a portion of the rabbit genes for costimulatory molecules. The primers HCD28S1 (5'-AAGTAA-CAGGAAACAAGATTTTGGT-3', nucleotides of human CD28 143-167) and HCD28A2 (5'-GCGGCGGGGAGT-CATGTTCAT-3', nucleotides of human CD28 693-673) were synthesized according to the nucleotide sequence of the human CD28 gene (Aruffo and Seed 1987). The primers The nucleotide sequence data reported in this paper have been submitted to the GSDB, DDBJ, EMBL, and NCBI nucleotide sequence databases and have been assigned the accession numbers D49841 (RCD28), D49844 (RCTLA-4), D49842 (RCD80), and D49843 (RCD86)