First isolation step of a plasma factor which enhances lymphocytic cortisol metabolism and which is reduced in cancer patients.

Our previous findings show that cancer patients' plasma lacks a factor (LCMEF) which is characterized by its ability to enhance lymphocytic cortisol metabolism. In the present study, using the dialysis method, we tried to evaluate the size of that factor. Plasma of healthy donors (HP) was dialyzed against water. Human lymphocytes from healthy donors were incubated with cortisol in media containing buffer (PBS) and one of the following additions: 1) dialyzate, 2) dialyzed HP (DP), 3) reconstituted HP (DP + P). The cortisol conversion rates were compared with that obtained with untreated HP and with PBS. The results showed no significant differences among the conversion rates obtained with HP, dialyzate, and reconstituted HP. Dialyzed plasma, however, showed a significantly lower rate, which was equal to that obtained with PBS. This implies that the factors are smaller than 10,000 daltons.