Abstract
Peripheral blood mononuclear cells (PBMC) from 40 patients with gastrointestinal carcinoma (GIC), 13 patients with primary carcinoma in other localizations(non-GIC), and from 57 apparently healthy donors were isolated by Ficoll-Paque gradient centrifugation. The separated cells were stained with several monoclonal antibodies and subjected to analysis on a fluorescence-activated cell sorter. A decreased percentage of PBMC expressing T cell antigens was noted amongst GIC patients, and was mainly due to a reduction of the Leu 2a subset, thus, leading to an increase in the Leu 3a/Leu 2a ratio from 1.4 to 2.1 Non-GIC patients had decreased numbers of both T helper and suppressor cells. Amongst PBMC from GIC and non-GIC patients a statistically increased percentage of cells expressed LeuM 2 (P less than 0.001), LeuM 3 (P less than 0.001), OKM 1 (P less than 0.005), VEP 9 (P less than 0.001), and HLA-DR (P less than 0.001) antigens compared to healthy controls. The percentage of cells bearing these monocyte/macrophage antigens correlated well with the number of cells having monocyte morphology, stained for non-specific esterase, phagocytosed latex particles, and expressed Fc IgG receptor. Our results demonstrate clearly that tumor-bearing patients have an increased relative number of monocytes. The data suggest that cells of the macrophage lineage may be involved in defense mechanisms and changes of the immune system evoked by various tumors.