Immunization with an antigen identified by cytokine tumor vaccine-assisted SEREX (CAS) suppressed growth of the rat 9L glioma in vivo

We have reported previously that s.c. immunization of rats with IL-4 transduced 9L gliosarcoma cells (9L-IL-4) induced a potent antitumor immunity against intracranial, parental 9L tumors. Subcutaneous implantation of 9L-IL-4 influenced the systemic humoral response, which was demonstrated by Th2-type isotype-switching and the induction of cellular immune responses, which played a critical role in the rejection of tumors. Serological analyses of recombinant cDNA expression libraries (SEREX), has recently emerged as a powerful method for serological identification of tumor-associated antigens (TAAs) and/or tumor rejection antigens (TRAs). Because IL-4 is known to activate B cells and to promote humoral responses, and inasmuch as induction of humoral responses by central nervous system tumors has been reported to be minimal, we investigated whether the induction of a potent humoral immune response against 9L TAAs or TRAs in rats immunized s.c. with 9L-IL4 could be demonstrated. Screening of 5 x 10(5) independent clones of 9L-expression cDNA library for the presence of reactive antibodies in the serum from a 91-IL-4 immunized rat led to the identification of three different TAAs. One 9L TAA (clone 29) was demonstrated to be calcyclin, a member of the S-100 family of calcium-binding proteins. The second 9L TAA (clone 37) was demonstrated to be the rat homologue of the J6B7 mouse immunomodulatory molecule. The third TAA (clones 158 and 171) was determined to be the rat homologue of the mouse Id-associated protein 1 (MIDA1), a DNA-binding, protein-associated protein. Northern blotting demonstrated that message for calcyclin was overexpressed in 9L cells. Message encoding MIDA1 was highly expressed in parental 9L cells and thymus and, to a lesser degree, in testis, suggesting that MIDA1 was comparable with the cancer/testis category of TAAs. Sera obtained from animals bearing 9L-IL-4 were found to have a higher a frequency and titer of antibodies to these antigens when compared with sera obtained from rats bearing sham-transduced 9L (9L-neo) cells. To determine whether immunization with these TAAs induced antitumor immunity, animals were immunized by intradermal injection with expression plasmids encoding calcyclin or MIDA1. Subsequent challenge of rats with parental 9L resulted in significant suppression of tumor growth in animals immunized with MIDA1, but not with calcyclin. These results indicate that MIDA1 is an effective 9L TRA and will be useful for the investigation of specific antitumor immunity in this glioma model. Furthermore, these results suggest that this approach, termed "cytokine-assisted SEREX (CAS)," may serve as an effective strategy for identification of TRAs for in animal-glioma models of cytokine gene therapy, and potentially in humans undergoing cytokine gene therapy protocols as well.

An intrasylvian "fibroma" in a child with cystic fibrosis: case report

OBJECTIVE AND IMPORTANCE

Intracranial fibrous tumors are uncommon during childhood. An unusual case of benign intrasylvian "fibroma" that has remained clinically and radiographically stable more than 3 years after a subtotal resection is described.

CLINICAL PRESENTATION

A 9-year-old girl with cystic fibrosis presented with new-onset focal seizures referable to a large calcified left sylvian fissure mass.

INTERVENTION

An open biopsy with subtotal resection of the lesion revealed a benign process characterized by exuberant fibrocollagenous tissue intermeshed with chronic inflammatory cells and foreign body giant cells, encompassing islands of gliotic brain tissue. Immunohistochemical analysis showed staining for epithelial membrane antigen and reticulin within some of the spindle cells, although the majority were nonreactive. The majority of tumor cells exhibited staining for laminin; CD34 staining was absent. Ultrastructural studies were also suggestive of a fibroblastic rather than a meningothelial origin of the lesion, with elongated cells separated by abundant extracellular collagen. Although dense adherence of the mass to the pial surface and the middle cerebral artery vessels precluded a complete resection, the patient remains seizure-free without anticonvulsant therapy more than 3 years postoperatively with no evidence of growth of the lesion.

CONCLUSION

The lesion in this patient bears morphological similarity to a rare group of tumors referred to as "intracerebral fibromas," although a variety of other rare mesenchymal neoplasms were also considered within the differential diagnosis. However, the absence of any definite neoplastic features, the finding of chronic inflammatory changes, and the lack of growth of the residual tumor during an extended follow-up interval indicate that the mass may represent either an extremely indolent neoplasm or a nonneoplastic process. The differential diagnosis of intracranial fibrous tumors is contrasted with that of the reported case.