Intron retention is proposed to play a role in Neutrophil mRNA expression influencing some (86) proteins involved in the maturation process (laminin2) of Neutrophils. See link below:
http://www.ncbi.nlm.nih.gov/pubmed/23911323
You should look for RNAseq data from neutrophils and upload them to the UCSC genome browser to see which introns are retained.