European Journal of Biomedical and Pharmaceutical Sciences

HEMATOLOGY IN THE SENESCENCE

Obeagu, Emmanuel Ifeanyi, Okoroiwu,I.L., Daniel-Igwe,Gloria, Ijioma Solomon Nnah

ABSTRACT

The hematopoietic system is modestly affected by aging, and these effects become particularly notable after age 65. There is a continuous decrease in the volume of the hematopoietic marrow with age, which does not cause significant alterations in either granulocyte, monocyte, or platelet counts, although a slight £1.0 g/dl decrease in population mean hemoglobin concentration in men occurs. The recruitment of neutrophils in response to exogenous stimuli is slightly decreased, but the response to infection does not appear impaired. Neutrophil function is not significantly decreased with age of the subject. Although the population mean vitamin B12 and folate levels decrease with age, these changes do not result in decreased hematopoiesis as judged by blood counts, except in individual patients with significant deficiencies. Anemia in older individuals should be evaluated in the same manner as anemia in younger individuals. Certain coagulation proteins are altered significantly with aging, and a propensity to accelerated coagulation and compensatory fibrinolysis is present, leading to a new steady state. Decreased immune cell function is the most consistent change in older persons and perhaps the most important functionally. Although there is a tendency to decreased lymphocyte counts in the blood, the major effects are mediated by dysregulation of T lymphocyte function, perhaps as a result of the prolonged period since thymic atrophy in older subjects. This change affects both cellular immune functions and antibody responses to antigens because of the T helper cell function required. Many studies of aging have to be interpreted in the light of inadequate population samples for study, the difficulty and therefore the rarity of using longitudinal as contrasted with cross-sectional analyses, the small sample sizes after stratification for gender and decade of age, and the need to study smaller age intervals in the 8th through 10th decades of life because of more dramatic changes over short intervals at these ages. In 1998, individuals 65 years of age or older accounted for 12.7 percent of the population of the United States; this group is expected to grow to 23.0 percent of the population by the year 2040. Currently, there are 4.0 million people in the United States who are 85 years old or older.1 Data from 1985 through 1989 indicate that life expectancy at age 65 is 14 years for males and 18 years for females in most developed countries(Kinsella,1992). As a result, physicians are increasingly caring for older patients and are being called upon to interpret hematologic data in the context of the age of the patient. Age-related effects on cellular DNA results in a dramatic increase in the incidence of clonal hematopoietic diseases, especially leukemia, lymphoma, myeloma, and closely related diseases in the decades after age 50. In addition, the decrease in immune function has an impact on vaccine use and resistance to infection in older individuals.

Keywords: Aging, Haematopoiesis, Marrow cellularity, Chromosome studies, Immune responses.