AIDS is a serious infectious disease with a high mortality rate that occurs when the human immunodeficiency virus (HIV) invades the human body.
Because HIV infection replicates in large numbers in the body, it selectively destroys CD4+ T lymphocytes, causing a decrease in the number of peripheral blood leukocytes and the total number of lymphocytes; among them, the absolute number of T helper lymphocytes (CD4+) decreases and the relative number of cytotoxic T lymphocytes (CD8+) increases; reversing the CD4+/CD8+ ratio and causing HIV in approximately 50% to 70% of infected patients. Viraemia and acute damage to the immune system occur in approximately 50% to 70% of infected individuals, so that high-risk individuals may experience low lymphocyte counts during the incubation period of AIDS and develop symptoms of upper respiratory tract infection such as fever, malaise, sore throat and general malaise. However, the symptoms of AIDS are very atypical, and low lymphocytes cannot determine whether HIV infection is present. Normal reference value of lymphocytes: adults (0.8-4) × 10*9/L. High lymphocytes include both absolute and relative increases.
Absolute increase: Physiological increase of lymphocytes includes higher in the afternoon and evening than in the morning. Lymphocytes in infants 1 week after birth can reach more than 50%, which can last for 6~7 years, and then gradually decrease to adult level. Pathological increase in lymphocytes is commonly caused by: infectious diseases (recovery from typical acute bacterial infections, acute infectious diseases caused by certain viruses, recovery or chronic phase of certain chronic infections such as tuberculosis); neoplastic diseases (predominantly primitive and naive lymphocytosis: acute lymphocytic leukemia, acute changes of chronic lymphocytic leukemia; predominantly mature lymphocytosis: chronic lymphocytic leukemia, lymphocytic lymphoma); post-transplantation of tissues (absolute increase in lymph count in the pre-rejection period, which can be used as one of the indicators for monitoring rejection of tissue and organ transplants); certain hematological diseases (aplastic anemia, granulocytopenia and granulocyte deficiency are relative increases in lymphocytes); drugs (aspirin, levodopa, phenobarbital, etc.)
Relative increase: The relative increase in lymphocyte ratio is mainly due to a decrease in the number of other cells due to some causes, but the absolute value of lymphocytes is not increased, such as aplastic anemia, granulocytopenia, and granulocyte deficiency.
In general, the number of lymphocytes is reduced in AIDS patients, but it is not possible to determine whether HIV infection is caused by the reduction of lymphocytes alone, and there are many reasons for the high lymphocyte count.