Macrophage precursor cells in blood from healthy individuals and from cancer patients

Krikorian, Garry (1973) Macrophage precursor cells in blood from healthy individuals and from cancer patients. Masters thesis, Memorial University of Newfoundland.

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Abstract

An original method for counting macrophage precursors from peripheral blood is presented. The interest in developing this method lay in an unresolved question about macrophage behaviour in patients with cancer. -- It is known that patients with advanced cancer have reduced cell-mediated immunity, as shown by poor delayed responses to intradermal injections of a wide range or microbial antigens. Furthermore it has been demonstrated that the cellular response to abrasion of the skin in cancer patients shows a significant reduction in the number of macrophages appearing, when compared with the same response in control individuals. It is likely that the reduced macrophage response and the reduced cell-mediated immune response are causally related. This reduced mononuclear response could be due to a numerical reduction of macrophage precursors in the bloodstream. The objective of this thesis was to investigate this possibility by counting the number of macrophage precursors in the bloodstream. -- The method for counting macrophage precursors entails culturing a leukocyte suspension for seven days. During this period of incubation precursor cells develop into macrophages. The macrophage preparations can be fixed in situ, stained and the macrophages counted. No preferential loss of any type of white cell was observed during the various stages of preparation of the leukocyte suspension, thus indicating the validity of the method. Furthermore the macrophages are non-dividing cells under these conditions. Tests of reliability of the method were considered satisfactory. -- The number of macrophage precursors in 24 healthy adults averaged 3-4 of the white cells in the blood. The higher the total number of white cells, the higher the number of macrophage precursors. -- In a preliminary study seven patients with cancer were compared with seven healthy control subjects; there was no significant difference in the number of macrophage precursors in the two groups. Thus, if these preliminary results are confirmed, the reduced macrophage emigration onto skin windows that has been observed by others in cancer patients can best be explained by a failure of chemotactic mechanisms. Statistical analysis of the haematologic data in the cancer group as compared with the healthy controls revealed one significant difference. In healthy people the number of macrophage precursors correlated positively with the total white cell count; on the other hand, in the cancer group there was no such correlation. This difference between correlations in healthy controls and cancer patients is statistically highly significant.

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