[Bioinformatic analysis and identification for a novel antigen MLAA-22 in acute monocytic leukemia]

This study was aimed to investigate a novel MLAA-22 antigen derived from a U937 cDNA library by the SEREX approach and search for gene expression in various samples. Bioinformatic analysis was performed to forecast MLAA-22 information mined from databases and experimental datasets. CTL epitope was predictied and the specific antibody for MLAA-22 was elicited by using peptide-microspheres and adjuvants. Furthermore, SYBR Green real-time PCR and immunoblotting method were used to evaluate the specificity of gene expression. The results showed that the full length cDNA of MLAA-22 located on chromosome 17q11.2 was 2.0 kb in size, and a putative protein was approximately 72.4 kD for 631 amino acids. The MLAA-22 encoded a cancer/testis antigen in human, which is nonsecreting type, plasmosin, labile protein, hydrophilia, thermostability, and without signal peptide. Many motifs might related to growth, proliferation, differentiation, and apoptosis. Antigenic peptides was synthesized as the antigen with Fmoc/PyBOP method. Rabbits were immunized by injecting the synthetic peptide-KLH to obtain antibody and the immune sera analyzed with ELISA were 1:8000. SYBR Green real-time PCR and Western blot showed that MLAA-22 presented with a higher number of copy messages in M(5), lower in CML, but not in gastric carcinoma, renal carcinoma, LNCaP cell lines and normal adult tissues, etc. It is concluded that mlaa-22 is a novel acute monocytic leukemia-associated antigen gene and be extended to further discovery.