Rama Ganguly

Inhibition of Yeast Phagocytosis in Macrophage Cultures Treated With Slime Polysaccharide Purified From Pseudomonas aeruginosa

This study was initiated to determine whether purified slime polysacchar‐ ide(PSP) from P aeruginosa inhibits the ingestion of heat killed Saccharomyces cerevisiae particles in macrophage cultures. Relative to controls, direct phagocytosis assays revealed that the percentages of phagocytes and the numbers of ingested yeast particles per phagocyte decreased in a dose‐dependent manner in PSP‐treated cultures. Thus, PSP may act as a virulence factor in vivo by impairing the phagocytic capacity of macrophages.

Influence of physician's recommendation on influenza immunization: perception and acceptance among a group of institutionalized elderly

Abstract Elderly residents (201, mostly male ≥ 65 years old) from the VA nursing home care unit (NHCU) in Florida were surveyed by a questionnaire as to whether they had been voluntarily accepting influenza vaccine in the past and what factors had affected their decision. These veterans had an average length of stay at the NHCU of 12 months and ≥ 70% suffered from chronic diseases with a past history of smoking. Physician recommendation concerning immunization was found to be the most significant factor for vaccine compliance. Over half of the residents immunized within the past year could recall a physician personally giving a recommendation for vaccination. Among those not immunized during the year, 22% did not have yearly physicians recommendation and cited reasons such as unawareness of vaccine need, 20% disliked or feared the side effects and 14% lacked general motivation. These data indicate that physician intervention plays a strong role in the acceptance of influenza vaccination among hospitalized elderly veterans and appears to be more effective than the usual standing NHCU practice of vaccine offered by the nursing staff. The data also suggest that educational intervention measures may be beneficial, yet, not as effective as physicians intervention.

Factors affecting prophylactic immunization compliance in elderly veterans: A study of pneumococcal immunization in the aged

Immunization among the high risk groups, including the elderly, remains unacceptably low for pneumococcal and influenza vaccines. This study determined the factors which influence pneumococcal vaccine compliance in the aged. A questionnaire developed for this study was mailed to all 300 veterans in west central Florida who were 85 years or older and were eligible for ambulant medical care at the James A. Haley Veterans Hospital, Tampa, Florida. They were asked regarding circumstances which influenced their decision for or against accepting pneumococcal vaccine. Ninety-two persons responded in self-addressed stamped envelopes and data were analyzed six months following mailing date. The single most important factor for not accepting vaccination was lack of information and unawareness that the immunization was necessary (81%). Fear of “shots” and side effects was the next most important reason for not taking the vaccine (15%). Lack of transportation to the doctor’s office prevented 12% of the subjects. Some subjects also did not have an interest in prophylactic immunization (8%).These data suggest that the lack of awareness, knowledge and information about pneumococcal immunization plays major roles in its poor acceptance among the elderly. Health education measures should improve vaccine compliance in this population who suffer from higher death rates and complications from pneumonia.

Immunologic Competence of Hemodialysis Patients following Withdrawal of Vitamin C Supplement

Twelve stable nondiabetic patients on chronic hemodialysis were studied for their immunobiologic competence while receiving vitamin C supplement and 1-2 months following its withdrawal. These subjects, on prescribed diets, were checked for their food intake at the beginning of the study and at 1-month intervals thereafter. Immunological parameters tested were: (1) plasma vitamin C levels; (2) number of mononuclear cells isolated from blood and their vitamin C contents; (3) lymphocyte blastogenic response to mitogens; (4) leukocyte metabolic functions in presence of endotoxin by nitroblue tetrazolium reduction test, and (5) delayed hypersensitivity to skin-testing antigens, e.g. Candida and mumps antigens and purified protein derivative. Patients on vitamin C had significantly higher plasma ascorbic acid levels compared to normal healthy subjects. These decreased to low normal levels 1 month following withdrawal of the supplement and stayed comparable thereafter, up to 12 months of the study period. Ascorbic acid contents in the isolated mononuclear cells remained unchanged in patients on or off vitamin C. The number of blood mononuclear cells isolated and mitogenic responses to concanavalin A and phytohemagglutinin did not change following withdrawal of vitamin C supplement. All patients had positive delayed hypersensitivity to Candida, 60% to mumps and all were unresponsive to purified protein derivative. Leukocyte metabolic functions by nitroblue tetrazolium reduction test were higher in patients on vitamin C than when off, but this was not statistically significant. Vitamin C supplement is not necessary in hemodialysis patients when they are on an adequate diet.

Age and immunity to respiratory tract infections

Immunological reactions that occur in the respiratory tract in response to infectious agents have recently gained distinct attention. Humoral (1–20) and cellular immune reactions (16, 21–34) have been identified in the lungs of a number of animal species and of man. Respiratory tract infections occur frequently among the elderly and constitute one of the leading causes of death. Aged humans have a greater mortality from pneumonia (35), influenza (36), tuberculosis (37), infective endocarditis (38), urinary tract (39) and intraabdominal (40) infections. Perla and Marmorston reviewed the effects of aging on natural resistance to infection (41–42), and focused on four factors as major determinants of resistance in old age: (a) changes in structure and function of vital organs, especially endocrine glands and the splenic lymphatic apparatus; (b) underlying pathological conditions facilitating microbial invasion; (c) alterations in circulatory and nervous systems which lead to trophic changes and tissue anoxia; and (d) prolonged subclinical vitamin and mineral deficiencies. Some investigators have postulated that the predisposition of the aged to infections is not due to a declining immune response (42–43), rather than to other physiologic changes of aging. Many studies of animals and man have linked the increase of infectious disease in the aged to reduced immunological vigor (44–47), in particular, deficiency of T-cell dependent immune responses (reviewed in 48–51). These studies which focused on the circulating immune system (peripheral blood, spleen, and peripheral lymph nodes) while clearly important, have not included information on age-related changes in the mucosal immune system. Studies on mucosal immunity are obviously relevant for elucidating the mechanisms of infectious diseases in the elderly. The importance of such information is emphasized by accumulating evidence that microorganisms entering the host encounter a functionally compartmentalized and distinct lymphoid area underlying the mucosal surfaces of the lung, genital tract, and intestine. These distinct lymphoid areas are characterized by unique immune cell populations, cell trafficking and homing patterns, and immune responsiveness (reviewed in 48, 52–54).This critique will review and present work on local immune functions of the nasopharyngeal tract, with particular emphasis to the age-associated decline in resistance to infections. The meager data available in the literature wlll be organized in this review under humoral and cellular aspects of both animal and human studies.

Lung defenses in aging: Responses to influenza vaccine and inflammatory stimuli

This study examined the immunobiologic properties of the respiratory tract in young adult and aged rats. Macrophages obtained by lung lavage technique were enumerated and tested in vitro for migratory, phagocytic and fungicidal activities. Bronchoalveolar lavage (BAL) fluids from the animals were assessed for C5 cleaving activities. Circulatory antibody responses following intranasal immunization with influenza subunit vaccine were determined by ELISA technique. Total numbers of alveolar cells and their differential distribution were comparable between the two groups. Phagocytosis and fungicidal capabilities of the lung-derived macrophages at 60, 120, and 180 minutes of incubation were not different in young adult and aged animals. Random and directed migration of macrophages in vitro remained unaltered. C5 cleaving activities of the BAL fluids were significantly enhanced in the aged animals. In contrast, specific antibody responses to influenza vaccine declined in the aged rats compared to the young adult rats. Aging may adversely affect immunologic balance of the respiratory tract by reducing specific protective immune responses and enhancing ability to mount inflammatory reactions.

Immunization against viral infections. Successful, ongoing mode of defense.

The body protects itself from disease through a variety of innate defense mechanisms and through immunity acquired both passively and actively. Passive immunization is achieved through transfer of antibody or of sensitized lymphocytes or their soluble products from an immune donor, while active immunization is achieved through stimulation of the recipients own protective mechanism by means of exposure to the disease or to pathogens or their toxoids. Among the diseases brought under control or eradicated by means of active immunization are smallpox, polio, and measles. Vaccines for immunization against several other diseases are already being used successfully and further ones are being developed.

Aging and local immunity against respiratory tract infections

Abstract Secretory IgA is the predominant immunoglobulin in human respiratory and oropharyngeal secretions. IgA antibodies against a number of microbial pathogens are found in nasal secretions and correlate with protection. The mononuclear phagocytes also play vital roles in eliciting specific immune responses in the upper and lower airways. They process antigens and present them to the immunocompetent cells and also are activated by various lymphokines generated locally in the respiratory tract for protection against intracellular pathogens. Little information is available regarding age associated changes in the lung protective mechanism with regard to respiratory tract infections. The mechanisms of age-associated deficiencies of the lung protective functions are undoubtedly complex and include anatomical, physiological and immunological changes. Existing data indicate that in humans, opsonic functions and secretory IgA contents of the respiratory and oropharyngeal tract secretions may be altered in the aging. In various animal model studies, T-cell dependent functions appear to decline. The normal aging process in mice is associated with changes in the manner in which the respiratory tract reacts to common microbial pathogens, in particular, the size of the inoculum. In rats and guinea-pigs, local lung mononuclear cell-mediated responses to intracellular microbial organisms decline with age. Immune responses to intra-nasal influenza hemagglutinin vaccine appear to be depressed in the aged rats compared to young adult rats. Contrarily, the amplification pathway for mounting active inflammation (C′ cleaving activity) is enhanced in this animal model, indicating the potential for lung damage from polymorphonuclear leukocytes. These observations suggest an adverse effect of age on the immunologic balance for disease prevention. Thus, an excessive response to an inflammatory stimulus couple with a reduced development of protective immunity might lead the aged to compromised host defenses.