Cellular aging of the reticuloendothelial system

The reticuloendothelial system (RES) consists of macrophages and other endocytic cells which contribute to natural resistance to disease agents. The RES has been implicated as being partly responsible for the observed age-related decrease in resistance to pathogenic microorganisms in man and experimental animals. It is largely unknown to what extent age-related deficiencies in specific functions of reticuloendothelial cells contribute to the decrease of RES functions. This study describes experiments focussed on Kupffer and endothelial cells of the liver which represent a major part of the RES and are primarily responsible for clearance of potentially harmful substances from the circulation. The age-related changes in the clearance of a RES test colloid (heat-aggregated colloidal albumin (CA)) and of E. coli endotoxin were investigated using female BN/BiRij rats of various age groups. With CA, studies were performed on the plasma clearance and on the endocytic capacity of whole liver and of Kupffer and endothelial cells in vivo, as well as on the kinetics of endocytosis by Kupffer cells in culture. The results showed that the plasma disappearance of endotoxin was significantly prolonged in rats of 24 and 36 months resulting in an increase in half-life of about 50% as compared to young rats. The plasma clearance of CA, the uptake by the liver and the endocytosis by endothelial cells were unchanged with age. In contrast, an age-related decrease in endocytic capacity was observed in Kupffer cells in vivo and in Kupffer cells which were isolated from rats of various ages and maintained in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of neutrophil function in the elderly using antibody coated polyacrylamide gel (immunobeads) and nitroblue tetrazolium (NBT) reduction as a combined test

Neutrophil function was assessed in 35 elderly individuals (age greater than 75) and 20 normal young individuals (age 20-45) by combining ingestion of antibody coated polyacrylamide gel and nitroblue tetrazolium reduction in a single test. This test evaluates phagocytosis and metabolic integrity simultaneously and appears to be a sensitive and reliable test of neutrophil function. No significant difference was found (by using this test) between neutrophils from healthy elderly people and the neutrophils from young controls, or between the sexes in either age group.

Ageing and the immune response--a unifying hypothesis?

In this article we review the abnormalities in immune function which have been described in relation to ageing. It is suggested that thymic involution may not be the only underlying cause. Many similar changes can be induced by the endotoxins from the cell walls of Gram-negative bacteria. The colon is a large repository for these organism and bacterial breakdown products are found in portal venous blood. Spillover into the peripheral circulation is prevented by the hepatic Kupffer cells degrading these substances. A waning in Kupffer cell function is well documented in association with ageing and there may be spillover of endotoxins into the peripheral circulation in elderly individuals. It is suggested that such spillover of endotoxins may contribute to some of the immunological changes previously attributed to ageing.

Immunological abnormalities in patients with chronic bronchial suppuration: a possible relationship with endotoxaemia

Chronic bronchial suppuration has been associated with elevations in immunoglobulin levels, circulating autoantibodies and immune complexes but the cause is obscure. In order to investigate one possible explanation we studied eight male subjects (mean age 54.9 years, range 39-68) and 16 female subjects (mean age 45.2 years, range 24-68) with bronchial suppuration attributed to bronchiectasis. Gram-negative organisms were found in the sputum of 95% of subjects. Forty per cent (10 subjects) had elevations in immunoglobulin levels and 60% (15 subjects) had circulating autoantibodies. Eighty-eight per cent (21 subjects) had mild-moderate increases in the level of C-reactive protein. Endotoxin was detected using the limulus amoebocyte lysate test in 50% (12 subjects). Endotoxin was found only in patients with an immunological abnormality and was more likely to be detected in those with both elevated immunoglobulins and circulatory autoantibodies. It is suggested that the endotoxin may be of aetiological significance in the development of autoantibodies and elevations of immunoglobulin levels.

The frequency of physical signs usually attributed to meningeal irritation in elderly patients

Nuchal rigidity, which may be a sign of meningitis, was found in 35 per cent of geriatric patients on acute-care and rehabilitation wards and in 13 per cent of younger patients on an acute-care ward. It was significantly associated with cerebrovascular disease, confusion, abnormal plantar responses, and primitive reflexes. Elderly patients who have nuchal rigidity with no history of neurologic or cognitive disorders should be investigated for meningitis.

Cardiopulmonary resuscitation of old people

In a prospective study, cardiopulmonary resuscitation was attempted in 52 elderly patients (mean age 75.6 yr, range 64-91). Of 14 who were resuscitated initially, 5 died in the first week. Of the 9 still alive at one month (mean age 75.3, range 65-85), none seemed to have adverse effects, in terms of mental status or physical dependence, from the episode of cardiac arrest and resuscitation; 7 had left hospital. The nature of the cardiac dysrhythmia is a strong predictor of outcome. Age, sex, and time of arrest are not.

Necropsies in the elderly

A retrospective analysis of 332 necropsies in the over-65-year-olds and 129 necropsies in the over 85-year-olds (overall necropsy rate 35%) showed that the commonest cause of death in elderly patients admitted acutely to hospital was pneumonic illnesses. 27-31% of the necropsies revealed the presence of a potentially treatable contributory factor to death that was undiagnosed during life. In only 4.5% of the necropsies in the over-85-year-olds was the cause of death uncertain.

Gynecologic sepsis as a cause of covert infection in old age

Three cases of endometritis, which presented covertly in elderly women, are described. All three patients were in a poor state of nutrition, and two had serious intercurrent disease. It is believed that cyclical shedding of the endometrium and "normal" vaginal flora (under the influence of estrogen) are the major defenses against infection. These are lost after the menopause, and were therefore absent in the three patients described here. The waning of the immune response associated with aging, particularly the progesterone-stimulated uptake of polymeric IgA in the endometrium, may be important, as may the immunosuppressive effect of malnutrition. It is suggested that a nonspecific deterioration in an elderly woman or infection of uncertain site should prompt a careful re-examination, including a thorough pelvic examination.

The white nails of old age (neapolitan nails)

Nail changes similar to those reported by Terry and Lindsay were defined in an elderly inpatient population. Two hundred fifty-eight patients were studied, and an overall incidence of 19 per cent was found. There was no significant difference between men and women. The only significant correlations in this study were with osteoporosis and thin skin. Eight men with nail changes were compared with seven men without such changes by calculating the metacarpal index of cortical bone mass. The index was much lower in patients with nail changes (t = 2.64; P less than 0.01). All patients with nail changes had thin skin. No correlations were found with serum albumin, liver function, or kidney function. These nail changes are less frequent in the "less frail" elderly living in the community. Changes of the Terry type are common in children but disappear by early adult life. It is suggested that the nail changes are age-related phenomena and that they may reflect an underlying disturbance of collagen being manifested as changes in the nail bed, skin, and bone.