The invention concerns CD40 skipping 5 nucleic acid sequences and amino acid sequences obtained by alternative splicing of CD40, pharmaceutical compositions comprising said sequences and methods for treatment of a disease, wherein a beneficial therapeutic effect is achieved by the up regulation of the CD40-R-CD40-L interaction. An antibody capable of selectively binding to the amino acid of CD40 skipping 5 and pharmaceutical composition comprising the above antibody and methods for detecting the presence of exon 5 skipping expression in a sample are also within the scope of the invention.