title: Analysis of the age-related refractoriness of T-lymphocyte reactivity in humans.
abstract: Aged individuals could be divided into two groups according to their T-lymphocyte transformation values. The relationship between the PHA (phytohemagglutinin) stimulation indices and spontaneous thymidine incorporation; the PHA dose-response type distribution and the relative number of resting T lymphocytes was similar to the control group in aged subjects of seemingly intact T lymphocyte transformation values. However, their B cell compartment was found to be reduced. On the other hand, the ratio between the stimulation indices and spontaneous thymidine incorporation values of aged subjects of impaired T lymphocyte reactivity deviated from that of the control group. This group had an increased frequency of subjects giving maximal transformation values at relatively high PHA doses (hyposensitives) at the expense of normosensitives and showed reduced numbers of resting T cells, but normal B cell compartment. These results suggest that immunodeficiencies developing with age can possibly be of individually different types.
mesh_terms: D000375:Aging; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D006801:Humans; D008213:Lymphocyte Activation; D010835:Phytohemagglutinins / Q000494:pharmacology; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism
chemical_list: D010835:Phytohemagglutinins; D013936:Thymidine