RESUMO
Serum of patients with small cell lung cancer as well as serum fractions recovered by column chromatography inhibit the in vitro antibody synthesis in a PWM driven lymphocyte culture system and the capacity of T-lymphocytes to form rosettes with sheep erythrocytes. Utilizing an in vitro antibody synthesis system recomposed of previously separated B-cells and T-helper cells, we could show that the inhibiting high-molecular weight factors (between 40,000 to 60,000 dalton) from the patients' serum are suppressing antibody synthesis by inactivation of T-helper cell function. The mechanisms of inhibition are still unclear. The factors inhibiting E-rosette formation which are in the molecular weight range of 10,000 dalton and lower are not the same as the factors suppressing the antibody production.
