T-cell antigen receptor (TCR) membrane-negative T-cell mutants can be divided into two groups: 1) those which lack one of the six TCR polypeptides and 2) those which contain a mutated TCR chain. The present experiments reveal a new mechanism for the development of TCR membrane-negative T-cell variants: mutations in splicing consensus motifs causing excision or misreading of an entire exon (exon 3 of the TCRAC or TCRBC genes). C27.15 cells transcribe a TCR alpha chain consisting of TCRAVJCexon1Cexon2-encoded amino acids plus six new amino acids. The assembly defect seems to be that the truncated alpha chain does not interact with CD3 delta molecules; consequently, no TCR alphabeta/CD3 deltaepsilongammaepsilon complexes are formed. E6.E12 cells transcribe a TCR beta chain composed of TCRBVDJCexon1Cexon2-encoded amino acids plus twenty-seven new amino acids, which seem not to form a transmembrane region. The truncated beta chain does associate with CD3 gammaepsilon heterodimers, yet no TCR alphabeta/CD3 deltaepsilongammaepsilon complexes are made. This may be due either to low assembly of TCR beta/CD3 gammaepsilon trimers or to lack of access of the mutated TCR beta/CD3 gammaepsilon trimers to the TCR alpha/CD3 deltaepsilon compartment in the endoplasmic reticulum.

The use of reverse transcriptase in conjunction with the polymerase chain reaction (RT-PCR) has proven invaluable in the analysis of the T cell receptor (TCR) repertoire of different populations of T cells. However, the presence of a variable region in the T cell receptor has hindered the design of primers for the 5\' end of the TCR cDNA. We describe the design and use of a degenerate consensus primer that allows amplification of both the alpha and beta chains of the human TCR. We have used this primer in the analysis of the TCR distribution of T cell clones, peripheral blood lymphocytes and lymphocytes residing in tissue. In addition, the primer has allowed the identification of an alternative splice site in the beta chain constant region which cannot translate into a functional constant region. We have found the primer to be easy to use, sensitive and specific.