Inhibition of antibody synthesis and expression of T-cell membrane markers by serum factors of patients with small cell carcinoma of the lung.

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.