Cytotoxicity of sera from healthy persons and cancer patients

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Abstract
One hundred and forty sera from 68 cancer patients and 34 healthy persons were tested for cytotoxicity against human cell lines HEp2, AdenoCx 1 and Amnion B by using 20% test serum as the only serum in the culture medium and incubating for 5–7 days. Evaluation included cell counts, dye exclusion tests, and qualitative grading of cell growth on a basis of 0 to ++++. Final analyses were based entirely on the qualitative grading. Only sera which caused unequivocal toxicity (0 or + growth) were classified as cytotoxic.Cytotoxicity was unrelated to the cell line used for the tests. Toxicity gradually diminished during storage at ‐20° C, but reproducibility of repeated tests of the same serum was good if sera were stored less than 3 months. In studies of multiple serum specimens from the same individual, some persons, both cancer patients and healthy controls, showed inconstant toxicity which was not related to any recognized change in the donor's condition or activities. Toxicity was not related to sex or age. Toxicity was much more frequent in sera from patients with leukemia and lymphoma (74%) than in healthy controls (19%) and somewhat more frequent (39%) in sera from patients with other forms of cancer. Amongst the cancer patients toxicity was somewhat less frequent in sera from patients with the most aggressive cancers, but the difference could easily have occurred by chance. Medications (especially cancer chemotherapeutic agents), various„blood chemistry”︁ determinations, and blood counts had no clear relationships to serum toxicity, but the data did not exclude the possibility that certain medications (e.g. daunomycin) and certain metabolic abnormalities (e.g. uremia) cause sera to be toxic. Patients of blood group A more commonly had cytotoxic serum than did group O patients.The phenomenon of serum cytotoxicity offers no promise as a diagnostic test for cancer because of the frequency of both „false positive”︁ and „false negative”︁ reactions. Neither is it of prognostic value since it was not consistently related to survival or severity of disease. The increased frequency of cytotoxicity in sera from cancer patients as compared to healthy persons is highly significant statistically, but the cause and biological significance of the phenomenon remain an enigma.