Cloning, sequencing and expression of porcine CD40 ligand in Escherichia coli and human and porcine cells.

The CD40L ligand (CD40L) plays an important role in the interaction between antigen-specific T lymphocytes and antigen-presenting cells. The porcine CD40L encoding gene was isolated from porcine peripheral blood mononuclear cells (PBMC) using RT-PCR. Sequence analysis of the cloned CD40L gene showed an open reading frame of 786 base pairs encoding a 262 amino acid protein with a predicted molecular mass of 29 kD. The deduced amino acid sequence of the porcine CD40L shared 82%, 88% and 93% similarity with the CD40L protein of mouse, human and cattle. The isolated CD40L sequence was expressed as a hexahistidine fusion protein in Escherichia coli and purified by affinity chromatography. The analysis of the CD40L-expression in human 293 and porcine MAX cells by immunofluorescence showed its location on the cell surface.