Enhancing effect of hydrocortisone acetate administration on the content of A-type particles in Ehrlich ascites tumor

The incidence of intracytoplasmic A-particles was investigated in neoplastic and nonneoplastic cells of Swiss/ICR mice. The concentration of the virus-like particles decreased in the order of 1) invasive Ehrlich 4N ascites clone 1 tumor, 2) noninvasive Ehrlich 4N ascites clone 3 tumor, and 3) nonneoplastic cells of tumor-free mice. Four successive injections of hydrocortisone acetate, 1 mg/day/mouse, when administered after tumor inoculation, almost tripled the cellular content of A-particles in Ehrlich clone 1 tumor (P less than .001), whereas the same treatment given before tumor inoculation did not affect the particle content. The enhancing effect of the hormone was found to be dose-dependent (P = .0027). Possibly, hydrocortisone acetate accelerates the formation of A-particles by stimulating directly the virus-generating apparatus of clone 1 tumor cells.