The effect of low-dose cyclophosphamide and immunologic exposure upon growth of established Dunning R-3327-G subline rat prostate adenocarcinomas

Efficacy of immunopriming prior to isolation of tumor infiltrating lymphocytes for use in adoptive immunotherapy

Adoptive immunotherapy is dependent upon the leukocytic subsets isolated as tumor infiltrating lymphocytes (TIL) prior to in vitro expansion with interleukin-2. To favorably influence T-cell subset representation in TIL the efficacy of bacillus Calmette Guerin (BCG) and cyclophosphamide (CTX) priming was evaluated in rats bearing Dunning R3327-AT prostatic tumors. When assessed by immunohistochemistry, both agents significantly (p less than 0.001) increased helper-T representation and decreased that by suppressor-T cells. As a result helper/suppressor (H/S) T cell ratios of TIL from untreated tumors (0.73 +/- 0.11) were significantly (p less than 0.001) elevated by both BCG (1.93 +/- 0.39) and CTX (1.40 +/- 0.25). Immunopriming might enhance adoptive immunotherapy by increasing the H/S ratio of TIL prior to their culture.

Effect of cyclophosphamide on leukocytic subset distributions in rats carrying the Dunning R3327-MAT-LyLu prostatic adenocarcinoma

The Dunning R3327 adenocarcinoma represents a model for studying prostate cancer in rats; early studies have indicated its utility for studying relationships between tumor growth, immunologic markers, and chemotherapy. Normal animals and those bearing the metastatic Dunning R3327 MAT-LyLu tumor were treated with 10, 30, and 100 mg/kg doses of cyclophosphamide (CTX) and their spleens assayed for leukocytic subset distributions using monoclonal antibodies. Tumor-bearing animals had significant reductions in helper T cell content as well as reduced helper/suppressor T cell ratios, compared to controls. These effects occurred rapidly following implantation and were not reversed by chemotherapy. When administered to both tumor- and non-tumor-bearing animals, CTX also depleted T cell populations. Despite reductions produced in all subsets, two administrations of CTX (30 mg/kg) were capable of retaining (in non-tumor-bearing animals) or restoring (in tumor-bearing) normal helper/suppressor T cell ratios. Such studies aid in identifying therapeutically effective dosages of cytotoxic drugs that minimize their deleterious effects on the immune system.

Adherent spleen cell production of E series prostaglandins in rats bearing variants of the R3327 Dunning prostatic adenocarcinoma: effect of cyclophosphamide

Prostaglandins of the E series (PGE) have been implicated in many facets of immunoregulation, as well as having a possible role in metastatic dissemination. Variant sublines of the Dunning R3327 rat prostatic adenocarcinoma, differing in growth rate, hormonal responsiveness and in propensity for metastasis, were carried in Fisher X Copenhagen F1 animals. Adherent spleen cells were assayed in vitro for their ability to convert arachidonic acid to prostaglandins of the E series. These glass adherent cells presumably include the monocytic and T cell populations which have been implicated as being immunoregulatory. The results indicated that those spleen cells obtained from animals carrying the metastatic R3327-MAT-LyLu subline tumor converted more arachidonic acid to PGE's than cells derived from animals bearing non-metastatic sublines. Cyclophosphamide therapy did not alter such conversion. Multiple regulatory mechanisms for prostaglandin metabolism are suggested.