Electron microscopic analysis of regional lymph nodes in the process of cancer development

Aim. To study regional lymph nodes ultrastructure at different cancer stages, determine the reactive changes dynamics and identify the factors contributing to the inadequate local immune response and spread of tumor.

Methods. The regional lymph nodes obtained from 149 cancer patients during surgery for cancer of various localization were studied. Lymph nodes obtained from 32 apparently healthy individuals who died of accidental causes were used as a control. One part of lymph node, cut in two parts along the major axis, was used for the histological sections preparation, the second - for electron microscopy. A comparative study of the following groups of preparations was conducted: (1) lymph nodes of the control group; (2) lymph nodes without metastases in stage I cancer; (3) lymph nodes without metastases in stage II cancer; (4) the affected lymph nodes in the II and III stages with various volume metastasis.

Results. Ultrastructural changes in the regional lymph nodes in the process of cancer development have a certain dynamics: amid increasing microcirculation disorders and sclerotic processes, redistribution of immune cells and the immune reactions shift to B-cell humoral immunity occurs, resulting in the later stages to inactivation of T-cell-mediated immune reactions and macrophage-monocyte system, while maintaining plasmacytic reaction with high antibody-producing ability of the cells.

Conclusion. Factors, contributing to inadequate local immune response are: (a) a progressive decrease in the number of activated (immune) lymphocytes - main cytotoxic anticancer elements, in cancer development; (b) high amount of antibody-producing plasma cells, which can block T-cell cytotoxic effect by humoral antibodies, at all stages of cancer development; (c) decrease of the number of migrated (free) macrophages of monocytic origin and the fixed macrophages - sinuses reticular cells, phagocytic activity decrease; (d) the sclerotic processes and microcirculatory disorders that impede tumor cells and cytotoxic lymphocytes contact.