Requirement of the Macrophage or its Products for the Transformation of Cortisol-Resistant Human Lymphocytes by Phytohemagglutinin

Abstract

Cortisol was added to cultures of unpurified and column-purified human lymphocytes 30 minutes before addition of phytohemagglutinin (PHA). The per cent of blasts and macrophages was determined after 72 hours of incubation. Cell-rich plasma was also used to prepare 5 day-old cultures of adherent cells on coverslips. In some experiments Cortisol (10ug/ml) was added to half of the macrophage cultures. Adherent cells or cell-free supernatants from macrophage cultures were added to cultures of purified lymphocytes from the same donor. Test cultures were prepared with PHA alone or in combination with Cortisol.

The removal of adherent cells decreased the response to PHA in all experiments. Cortisol depressed PHA-stimulation and favored the survival of macrophages in unpurified cultures, but virtually abolished transformation by PHA in purified cultures. The addition of macrophages from untreated or Cortisol-treated cultures to purified lymphocytes restored the response to PHA, a response which was inhibited somewhat by preincubation with Cortisol. Tests with supernatants from untreated macrophage cultures also showed potentiation of blastogenesis, but the results with supernatants from Cortisol-treated cultures were equivocal. It was concluded that Cortisol-resistant T-lymphocytes not only gave rise to PHA-blasts which could coexist with large numbers of macrophages, but also required the macrophage or potentiating factors' produced by the macrophage for transformation by PHA.