Receptor-mediated gene transfer into macrophages.

Gene transfer systems targeting various receptors have been developed to introduce functional genes into cells in culture and into intact animals. A synthetic molecular conjugate, consisting of mannosylated polylysine that exploits endocytosis via the macrophage mannose receptor, was constructed and complexed to expression plasmids containing either the Photinus pyralis luciferase or Escherichia coli beta-galactosidase (lacZ) reporter genes. The DNA complexes were used to transfect murine macrophages isolated from peritoneal exudates in vitro. Luciferase and beta-galactosidase activity was found in transfected cells in culture, whereas complexes consisting of an irrelevant plasmid bound to mannosylated polylysine or the expression plasmid bound to galactosylated polylysine resulted in no detectable transgene expression. Gene transfer was inhibited by the addition of excess mannosylated bovine serum albumin to the culture medium before transfection. Reporter genes were also transferred into macrophages residing in the spleen and liver of adult animals using this system. Luciferase activity was maximal at 4 days after transfection and decreased to lower levels by 16 days. Transgene expression conformed to the distribution of cells that had nonspecific esterase, a cytochemical marker for macrophages. Thus, this system can be used to introduce functional genes into macrophages and may be an approach to the treatment of storage diseases that affect the reticuloendothelial system.

Identification of proacrosin binding protein sp32 precursor as a human cancer/testis antigen

Serological expression cloning of antigens eliciting a humoral immune response to a syngeneic mouse sarcoma identified pem (mouse placenta and embryonic expression gene) as a new member of the cancer/testis family. To identify the human homologue of pem, mouse pem sequences and pem-related expressed sequence tags from human testis were used as PCR primers for amplification using human testis cDNA. However, rather than pem, another gene, designated OY-TES-1, was isolated and found to be the human homologue of proacrosin binding protein sp32 precursor originally identified in mouse, guinea pig, and pig. OY-TES-1 maps to chromosome 12p12-p13 and contains 10 exons. Southern blot analysis suggests the presence of two OY-TES-1-related genes in the human genome. In normal tissues, OY-TES-1 mRNA was expressed only in testis, whereas in malignant tissues, a variable proportion of a wide array of cancers, including bladder, breast, lung, liver, and colon cancers, expressed OY-TES-1. Serological survey of 362 cancer patients with a range of different cancers showed antibody to OY-TES-1 in 25 patients. No OY-TES-1 sera reactivity was found in 20 normal individuals. These findings indicate that OY-TES-1 is an additional member of the cancer/testis family of antigens and that OY-TES-1 is immunogenic in humans.