Nucleolar organizer regions in the splenic lymphoid cells in low-birth- weight and full-term fetuses and newborns with pneumonia and sepsis

We studied the role of some morphological parameters and the nucleolar organizer regions (AgNORs) of splenic-follicle lymphoid cells, lymphocytes, and lymphoblasts in susceptibility of low-birth-weight (LBW) and full-term fetuses and newborns to bronchopneumonia and sepsis. The observed quantitative changes were compared with alterations in the synthesis of IgM by the studied cells. Full-term fetuses without antigenic effects exhibited a decrease in the number of AgNORs and in the nuclear area of the lymphocytes as compared with LBW fetuses. This was accompanied by an increase in the number of small lymphocytes and by a decrease in the number of lymphoblasts/10,000 μm². In newborns after the 6th day, the number of AgNORs increased, especially in the presence of infection (bronchopneumonia). These changes were related to the proliferation and transformation of lymphocytes into lymphoblasts. A sharp increase in the number of B and T lymphoblasts was the major sign of immune reaction to infection in fetuses and newborns: the number of IgM+ cells increased from 0.1 to 2.8/10,000 μm². In fetuses and newborns with sepsis, which is accompanied by inhibition and decompensation of immune reactions, the number of splenic follicles decreased to 1.9/mm² as compared to 4.9/mm² in fetuses with bronchopneumonia. This was related to a sharp decrease (by at least 15-fold) in the number of lymphocytes in the splenic follicles. The number of AgNORs also decreased significantly. A good correlation was found between quantitative changes in the number of AgNORs and number of lymphoblasts (r = 0.67) and the rate of mitosis of the lymphoid cells in the spleen (r = 0.97). The changes in lymphoid cell AgNOR are connected with these cells' reaction to infectious antigenic effects. The finding shows that the AgNOR changes presented here can be used as a reliable parameter in diagnostic practice for evaluating the inflammatory process in newborns.