Reactivity in the MEM-test of cancer patients' lymphocytes incubated with brain-derived preparations and extracts from malignant teratomas

Abstract

A batch of human encephalitogenic protein (HEP) was compared to preparations of microtubulin and associated proteins (MST) from guinea pig brain by serological techniques and the macrophage electrophoretic mobility (MEM) method. HEP consisted mainly of A1 protein and MST showed the characteristic double band in the 55,000 MW region and some additional weak protein bands. No cross-reactivity could be detected between HEP and MST by rabbit hyperimmune sera to these substances. The MEM test, however, revealed human lymphocyte reactivity to HEP and MST in both cancer and multiple sclerosis patients, but no remarkable responses in other patients. A synthetic nonapeptide (114-122 region of A1 protein) led to lymphokine release in 2 of 5 multiple sclerosis patients, in 1 of 13 cancer patients, and in none out of 13 control individuals. From these findings it is concluded that a minor component (contaminant?) present in both HEP and MST might induce lymphocyte responses in cancer patients. The A1 protein of HEP preparations is, if at all, not the only protein responsible for the so-called HEP-response of cancer patients. Continuing the MEM test experiments with extracts from single organ cancers, it could be shown that patients with malignant teratomas respond to a more or less broad spectrum of extracts bearing organ cancer specificity. On the other side, extracts made from 2 malignant teratoma tissues led to MEM responses in 8 of 13 cancers, in 2 of 11 control persons and in none of 5 multiple sclerosis patients. These findings underline the concept that tumour-associated antigens (possibly oncofetal antigens) do exist, which bear organ cancer specificity and will lead to a specific sensitization of the host. Such antigens may be expressed in teratomas in different qualities and amounts depending on the tissue differentiation capacity of a given teratoma.