Lymphotoxin cDNA clones from a HTLV-I-carrying T cell line HUT-102.

The conditioned medium of a HTLV-I-carrying T cell line HUT-102 showed cytotoxic activity against a mouse fibroblast cell line L-M. We prepared the cDNA library from HUT-102 poly(A)+ RNA and screened it using oligonucleotide probes that correspond to the amino acid sequences conserved in tumor necrosis factor (TNF) and lymphotoxin (LT). As a result we obtained two kinds of cDNA clones encoding LT in which amino acid residue 26t of mature LT is different; one is Asn and another is Thr. The sequence of the genomic clones obtained using a polymerase chain reaction method showed that the HUT-102 genome also contains two types of LT genes. Recombinant LTs expressed in Escherichia coli exhibited the same level of cytolytic activity against L-M cells. These results indicate that the cytotoxin constitutively produced by HUT-102 cells include two kinds of LT.