Infantile rickets reduces lymphocyte survival

Abstract

Increased incidence of infections had long been recognized in rachitic patients who were also described to have impaired lymphocytic functions. This study was designed to assess different apoptotic changes in peripheral lymphocytes in patients with infantile rickets in its various stages and to correlate these findings with the frequency of infection in this disease. The study included 24 rachitic patients with a mean age of 17.88 ± 7.65 months compared with 16 healthy matching controls. There were 7 rachitic patients who were in the active stage, 11 in the healing stage, and 6 in the healed stage. The enrolled cases were subjected to a full history and clinical examination. X-ray of extremities was performed, in addition to the laboratory tests including serum calcium, phosphorus, and alkaline phosphatase as well as direct immunofluorescence using flow cytometry with dual staining technique to check for apoptotic changes in peripheral lymphocytes. The results of the present study showed that the early apoptotic cells percent (EAC%), the late apoptotic and/or necrotic cells percent (LA and/or NC%), the NC%, and the total abnormal cells (%) of the lymphocytes were higher in the rachitic patients compared with healthy controls; although only the latter showed statistical significance. The EAC% of lymphocytes showed a trend to increase accompanied by a simultaneous decrease in the LA and/or NC% with the progression toward the healed rickets stage. The current study also showed a trend of the EAC% and LA and/or NC% of the lymphocytes to decrease with the doses of vitamin D shock therapy given to the rachitic patients. A significant positive correlation was demonstrated between the EAC% and the total abnormal cells (%) of the peripheral lymphocytes and the rate of chest infection in the rachitic cases in the 3 months previous to the study. In conclusion, rickets does not increase the rate of infection through local causes or immune cell dysfunction only, but it entails disturbed lymphocyte survival. The increased apoptotic tendency of peripheral lymphocytes in rickets is reversed with vitamin D therapy, which further emphasizes the importance of early prevention and proper treatment of such a disease.