Abstract
Frozen‐stored mononuclear cells were utilized in the leukocyte adherence inhibition (LAI) assay in studies which were designed to determine (1) the optimal concentration of breast adenocarcinoma and colon adenocarcinoma extracts, (2) the specificity of frozen‐stored cell responses to these extracts, (3) the optimal criteria for defining a positive response, (4) reproducibility of day‐to‐day testing, and (5) comparison of fresh mononuclear cells and frozen‐stored mononuclear cells obtained from individual bleeds. The optimal protein concentration of 3 M KCI extracts was found to be 100 μg/ml. Specificity studies were performed using frozen‐stored cells from cancer patients with positive reactivity to either breast or colon cancer extracts In contrast, normal donor frozen‐stored cells were prepared from blood specimens with no reactivity to breast or colon cancer extracts. In frozen‐stored cells of breast cancer patients a selected breast cancer extract elicited reponses in 27 of 30 cases (90%). In contrast, with these same cells, a colon cancer extract elicited responses in 3 of 13 cases (23%). In cells from colon cancer patients colon cancer extract elicited responses in 13 of 18 cases (72.2%) whereas breast cancer extract elicited responses in 3 of 18 cases (16.6%). One out of the 15 (6.7%) normal donor frozen‐stored cells was positive to breast cancer extract and none out of 12 were positive to colon cancer extract. Two‐way analysis of variance established the reproducibility of day‐to‐day testing in studies of samples obtained from four individual donors. Rank correlation established the dependence between fresh and frozen‐stored cells in studies of 15 individual donors. It is anticipated that studies using replicate frozen‐stored cell aliquots may aid in identifying antigenic activity following fractionation of antigenic extracts or in studying the properties of serum factors which specifically suppress responses to tumor extracts.