Reactivity in neoplasia, preneoplasia, and pregnancy of lymphocytes against fetal extracts: cross-reactions between man and mouse.

KCl extracts (3 M) from human fetuses were tested by macrophage electrophoretic mobility (MEMB), leukocyte migration inhibition, and/or leukocyte adherence inhibition techniques against lymphocytes-leukocytes from tumor-bearing humans and control persons. A positive MEMB test was found in 209 of 284 (73%) patients with various types of clinically manifest tumors. Only 15 of 134 (11%) controls gave a positive reaction by the MEMB test. Leukocyte migration was significantly inhibited in 48 of 64 (75%) tumor patients, and leukocyte adherence was significantly inhibited in 40 of 50 (80%) tumor patients versus 7 of 50 (14%) and 10 of 54 (19%) in the corresponding controls. Lymphocyte reactivity to fetal extracts is also detectable in inbred XVII/Bln, CBA/Bln, and C3H/Bln mice bearing spontaneous or transplanted tumors of different etiology. Human and mouse fetal extracts gave cross-reactions. Lymphocytes from tumor-bearing mice were reactive against fetal extracts from the cow, pig, sheep, guinea pig, cat, and chicken. Mice bearing benign skin warts induced by 7,12-dimethylbenz[a]anthracene (DMBA) as well as DMBA-treated mice without visible skin lesions gave a positive MEMB test. Likewise, pregnancy is associated with lymphocyte reactivity to fetal extracts.