Many hematologic studies have shown that the erythrocyte count decreases while the size of the individual cell increases in the aged. This study was performed in order to (1) evaluate changes in the blood erythrocyte level and mean erythrocyte size in the elderly and (2) evaluate use of the deoxyuridine (dU) supression test to determine whether deficiency of vitamin B12 or folate plays any role in age-related changes of hematopoiesis. Selected for study were 102 healthy men whose ages ranged from 20 to 79 years. The erythrocyte count and hemoglobin level decreased significantly, whereas the mean corpuscular volume and mean corpuscular hemoglobin increased after 70 years of age. Fresh bone-marrow cells were obtained from 10 young (20-38 yr) and 10 aged (70-82 yr) men. Wickramasinghe's dU suppression test was modified by application of an automatic cell harvester. The results were normal in both groups. Thus, the route of dU to dTMP in a DNA synthetic pathway appeared intact, and there was no evidence of B12 or folate deficiency in the aged to explain the observed macrocytosis. However, 3H-thymidine uptake by nucleated bone-marrow cells was significantly decreased, and the ratio of 3H-uridine to 3H-thymidine uptake was greater in the old group than in the young group. These results could be explained by altered nucleic acid metabolism (unbalanced cell growth) or by a change in the proportion of the different fractions of nucleated cells.

A role for specific cellular, as well as humoral immunity has been suggested in experimental adrenalitis. This study was performed to seek a correlation between cellular and humoral immunity in experimental adrenalitis of the guinea pig. 34 guinea pigs (GP) were arranged into 4 experimental groups. One group (11 GP) was immunized with a single injection of 250 mg homologous adrenal antigen (HAA) in complete Freund's adjuvant (CFA). A second group (6 GP) was similarly immunized at 1 and 14 days. A third group (9 GP) received 3 such injections at 1, 14, and 21 days. The fourth group (8 control GP) received RPMI-1640 in CFA. The following were performed on all groups 10 days after the last injection: lymphocyte response to PHA and HAA; HAA-specific macrophage migration inhibition (MIF); antibody titers to HAA by hemagglutination; and histopathology of adrenal, thyroid and testis. Antibody titers reached a mean level of 500 in each of the 3 HAA-immunized groups. In the single injection group, MIF activity and response to PHA were significantly increased when compared to the other immunized groups and to controls. Histopathologic changes were seen in adrenal glands of all immunized groups, but were most remarkable in the single injection group. Progressively fewer changes were observed in double and triple immunized groups. Antibody titers and histological changes were not found in controls. Histopathology correlated better with cell-mediated immune parameters than with specific antibody titers; this suggests that cell-mediated mechanisms may be the more important factor in pathologic lesions of experimental adrenalitis.

Wickramasinghe SN, Longland JE: Rate of incorporation of trifiated thymidine into DNA of normoblastic and megaloblastic bone marrow cells in vitro. Acta Haemat 52: 14-23, 1974. 5) Beck WS: The metabolic functions of vita

No abstract

No abstract