Laboratory models of minimal residual cancer; development and preliminary immunotherapy studies.

It is the author's contention that if we wish to investigate immunotherapy for cancer in laboratory models, the model must reproduce or at least mimic the biological conditions which are encountered in clinical oncologic practice. The usual experimental animal tumor systems do not satisfy this requirement. They are usually studied as primary transplants of rapidly progressive tumors which kill in a few weeks, and experimental treatments are usually started within a day of two after implantation, before the tumor is detectable by ordinary methods of examination. In clinical oncology the existence of cancer is seldom suspected until it reaches a clinically detectable mass, and it is then treated by various established methods which, if not curative, at least reduce tumor mass temporarily before the tumor recurs locally or at distant sites. A cancer patient, therefore, has a rather prolonged exposure to his tumor and an opportunity to develop immune and other biological responses to it. Present animal models are therefore inadequate for immunotherapy research. This paper examines the prerequisites for more accetable experimental tumor models for immunotherapeutic research, describes a step-by-step investigation leading to the development of what to seems to be more appropriate models, and describes preliminary immunotherapy studies in one of the models, in which parabiosis is used as a means of transfering antitumor resistance to the "patients" from specificially immunized donors.

Cataracts in bleomycin-treated rats.

Bleomycin was administered to 126 normal or human-tumor-bearing baby rats we observed for the development of cataracts. Eighty-four percent of the rats receiving this drug before the age of 10 days developed lens opacities. Bleomycin given to 10-day-old rats or older did not induce cataract formation. The cataracts initially occurred in the nuclear area and later involved most of the lens whether or not bleomycin was later discontinued. The presence of the tunica vasculosa lentis in rats younger than 10 days old may explain why cataracts developed only in these young animals.

Growth of human cancer cells as lung metastases in immunologically tolerant rats.

Newborn rats were made tolerant to human cell antigens by intravenous injection of Amnion B cells, a permanet human cell line of normal origin. At various intervals thereafter each animal, and nontolerant litter mate controls were challenged by SC and IV injections of the malignant human cell line J-III. Tumor nodules of J-III cells grew SC and in the lungs of most of the tolerant rats challenged at ages from 7 to 14 days, but not in their controls. Challenge at age 19 days produced SC tumors but there was no growth from the IV inoculum.

Inhibition of herpes simplex virus by synthetic double-stranded RNA (polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids).

Two-stranded polyriboadenylic and polyribouridylic acids and polyriboinosinic and polyribocytidylic acids protect against herpes simplex virus-induced cytopathogenicity in HEp 2 cultures, systemic herpes simplex virus infection in mice, and herpes simplex virus-induced keratoconjunctivitis in rabbits.