Transgenic mice lacking class I major histocompatibility complex-restricted T cells have delayed viral clearance and increased mortality after influenza virus challenge.

To investigate the role of CD8+ T lymphocytes in recovery from influenza pneumonia, we used transgenic mice either homozygous (-/-) or heterozygous (+/-) for beta 2-microglobulin (beta 2-M) gene disruption. These mice lack major histocompatibility complex-restricted class I (CD8+) T cells. We found that after challenge with a nonlethal influenza virus, the beta 2-M (-/-) mice had significantly delayed pulmonary viral clearance. Furthermore, after challenge with a more virulent influenza virus, the beta 2-M (-/-) mice had a significantly higher mortality rate than did control mice. Thus, CD8+ T cells are important in recovery from virulent influenza infections, but other host defense mechanisms can clear the respiratory tract of more benign infections.

Demonstration of defective C3-receptor-mediated clearance by the reticuloendothelial system in patients with acquired immunodeficiency syndrome.

The function of macrophage C3 receptors was assessed in vivo by measuring the clearance of C3-sensitized autologous erythrocytes in seven acquired immunodeficiency syndrome (AIDS) patients, eight healthy homosexual men, eight healthy heterosexual men, and four infected controls. Healthy heterosexual men had an initial clearance of 50.1 +/- 2.0% of the inoculum, with a release of a small portion of these cells (10.9 +/- 1.3%) into the circulation. Healthy homosexual men had a greater initial clearance of 66.0 +/- 4.2% (P less than 0.01) followed by a similar release (14.0 +/- 3.3%). AIDS patients had an initial clearance of 60.6 +/- 7.5% but had a relatively large release of cells (25.6 +/- 3.2%) (P less than 0.005 vs. heterosexuals; P less than 0.05 vs. homosexuals), suggesting a failure of macrophage phagocytosis. Infected controls had an initial clearance of 59.4 +/- 4.9%, with a release of 19.6 +/- 3.8% (P = NS vs. AIDS). These data, in addition to Fc-receptor dysfunction, demonstrate a global reticuloendothelial system dysfunction in AIDS patients. This may contribute to their frequent infections with opportunistic pathogens and inappropriate immune responses against these microorganisms.

Age differences in phagocytosis by polymorphonuclear leukocytes measured by flow cytometry.

Elderly persons have increased morbidity and mortality due to bacterial infections. Since the polymorphonuclear leukocyte (PMN) is a major defense against bacterial infection, we utilized fluorescent microspheres and flow cytometry to examine phagocytosis by PMNs from 55 young and middle-aged adults (mean age 41.5 yrs) and two groups of elderly subjects: one group of 35 healthy individuals (mean age 74.1 years) living at home, and a second group of 11 residents (mean age 83.1 years) with severe mental and physical disabilities, living in a domiciliary care facility. We determined the percent phagocytic PMNs, the number of microspheres per PMN, and the number of microspheres per 100 PMNs. The mean number of microspheres per phagocytic PMN was similar for all groups. Statistically significant differences were found between the young and middle-aged group and the healthy or ill elderly groups for the percent phagocytic PMNs (75.3% vs 51.5% and 43.8%), and the number of microspheres per 100 phagocytic PMNs (197.3 vs 131.4 and 103.2). There were no significant differences in these parameters between healthy and debilitated elderly subjects. These data document that there is an age-related increase in representation of a population of PMNs which have a defect in phagocytic ability.

Body temperature and nesting behavior following influenza challenge in mice: effects of age.

We studied the interaction of age and influenza on core body temperature (Tc) of mice. Following influenza challenge, 2-mo-old female BALB/c mice demonstrated a significant fall in Tc. Female BALB/c mice 24 mo of age had lower baseline Tc than young mice and a larger fall in Tc post influenza challenge. We noted there were marked differences in nesting behavior between the young and aged mice. A nesting score was devised, and we found that at baseline, aged mice had a much lower score than young mice (15.6 +/- 7.4 vs. 24.7 +/- 0.3, P < 0.0001). Following influenza challenge, nesting behavior of young mice dropped considerably, while no significant change occurred in the behavior of aged mice. When mice were housed without bedding, there were significant decreases in Tc of young, but not aged mice. There was a further fall in Tc with influenza challenge in young mice. These data imply that nesting is an important mechanism for maintaining Tc in young mice, but alternative mechanisms are used by aged mice. The lower body temperatures in the aged mice are similar to studies in aging humans.

Enhancement of anti-influenza cytotoxic T-lymphocyte activity in senescent mice by vaccination early in life.

The elderly suffer significantly from influenza and respond poorly to influenza vaccines. This may be due to the fact that cytotoxic T-lymphocyte (CTL) activity is responsible for recovery from viral infections and is decreased in the elderly. We hypothesized that vaccination early in life might increase activity in senescence. To test this, groups of BALB/c mice were infected with influenza virus and/or vaccinated with an inactivated vaccine. CTL activity was measured by 51Cr release from H1N1-infected P815 cells. We found that aged mice have low CTL activity when initially vaccinated at 22 months (4 +/- 4% vs. 23 +/- 6% for vaccinated young mice). However, CTL activity was significantly increased when animals were initially vaccinated when young and then re-vaccinated when old (28 +/- 10% vs. 13 +/- 17% for mice vaccinated twice in old age). We next measured CTL activity in response to infection. We found a very high level of activity (57 +/- 11%) in animals vaccinated at 1.5 months and then infected at 23 months. This was indistinguishable from young controls (56 +/- 7%). These data suggest that primary inoculation at an early age induces a relatively larger number of precursor CTLs than does inoculation in senescence.

Hematologic abnormalities in the acquired immune deficiency syndrome.

Blood and marrow specimens were evaluated from 12 patients with the acquired immune deficiency syndrome (AIDS). Ten patients were anemic, eight leukopenic, and three thrombocytopenic. Pancytopenia was present in two patients and subsequently developed in two others. Reticulocyte counts were not increased in the anemic patients. The most common peripheral blood abnormalities were a left shift in the granulocyte series, lymphopenia, atypical lymphocytes, and vacuolated monocytes. Marrow cellularity was increased in five patients and reduced in three. Marrow reticulin was increased in 10 patients; in three of these, marrow could not be obtained by aspiration. Plasma cells were increased in number in every marrow aspirate, and there was a left shift in the myeloid series in most. Aggregates of atypical lymphocytes or a diffuse increase in marrow lymphocytes occurred in seven patients. An increase in histiocytes was observed in seven marrow aspirates; in five of these, the histiocytes were phagocytizing red cells, white cells, and platelets. Necrosis was present in four marrow specimens. These hematologic abnormalities reflect, in part, the presence of systemic infection, inflammation, and the inanition associated with them. However, the high incidence of myelofibrosis, alterations in marrow cellularity, pancytopenia, and hematophagic histiocytosis indicates that the bone marrow is a target organ in AIDS.

Beta 2-microglobulin-deficient mice demonstrate class II MHC restricted anti-viral CD4+ but not CD8+ CTL against influenza-sensitized autologous splenocytes.

Mice transgenic for beta 2-microglobulin gene deletion (beta 2M-/-) can clear respiratory pathogens but at a slower rate than control mice. How these mice eliminate virus is not known, but the process is believed to involve CD4+ T cells. Recent studies from other laboratories have suggested a role for CD8+ cytotoxic T lymphocytes (CTLs) in both recognition of beta 2M deficient cells by allogeneic mice and rejection of MHC-incompatible tumor cells by beta 2M-/- mice. After influenza inoculation, we found no evidence for anti-influenza CD8 CTL activity from the lungs or spleens of beta 2M-/- mice. Anti-influenza CD4+, class-II restricted CTL activity was demonstrated from both the lungs and spleens. We next used mitogen-stimulated splenocytes from beta 2M-/- mice for targets in an in vitro CTL assay. This method for determining MHC class II CTL activity showed that the lungs and spleens of influenza-infected beta 2M-/- mice contained precursors to CD4+, but not CD8+, effector CTLs. The data indicate that CD8+ CTLs have no role in anti-viral activity in beta 2M-/- mice. Development of anti-tumor CTLs and anti-viral CTLs may arise via different mechanisms.

Peripheral but not central leptin prevents the immunosuppression associated with hypoleptinemia in rats.

Leptin is a peripheral immunoenhancing reagent that directly activates splenic lymphocytes in mice. We found that a 48 h fast in rats resulted in a decrease in serum leptin that was accompanied by a lower delayed-type hypersensitivity (DTH) response. Peripheral leptin replacement completely restored this response in fasted animals. We employed a recombinant adeno-associated virus (rAAV) system to deliver leptin gene directly into rat brain to assess the effect of sustained long-term central expression of leptin on immune responses. The rAAV-leptin rats had elevated central leptin over the 60 day duration of the experiment, whereas body fat and circulating leptin fell to near zero levels. The DTH response was significantly reduced by 10-20% in rats receiving rAAV-leptin compared with the control rats, and the difference was maintained for over 50 h. When the rats undergoing rAAV-leptin gene therapy were given either murine recombinant leptin or PBS s.c., rats receiving leptin had a 17% higher DTH response than rats receiving PBS. The isolated splenocytes from the former group also proliferated 34% more in vitro in response to the mitogen concanavalin A as compared with the latter group. These results suggest that peripheral leptin has a dominant role in maintaining T-cell-mediated immune responses in rats, and central leptin is unable to compensate for the immunosuppression associated with peripheral hypoleptinemia. Furthermore, preservation of normal cell-mediated immune responses does not require fat tissue as along as serum leptin levels are maintained.

The heterogeneity of the age-related decline in immune response: impairment in delayed-type hypersensitivity and cytotoxic T-lymphocyte activity occur independently.

Aged mice are known to have a heterogeneous cytotoxic T-lymphocyte (CTL) response to an influenza challenge. We sought to determine whether delayed-type hypersensitivity (DTH) to sheep red blood cells (SRBC) was also heterogeneous in aging and, if so, whether this correlated with anti-influenza CTL activity. Aged mice developed mean footpad swelling of 0.24 +/- 0.09 mm following SRBC challenge and mean CTL activity of 35 +/- 18%. Even though these values were significantly lower than those from young mice (0.54 +/- 0.10 mm and 51 +/- 2%, respectively), no correlation was found between anti-influenza CTL activity and DTH to SRBC (r = 0.01). We believe the most likely reason for this independent decline in immune response is because different activation signals are required for DTH and CTL activity. Our data thus suggest an age-related functional mosaicism in the immune system.

Serum antibody response to influenza vaccine in pulmonary patients receiving corticosteroids.

OBJECTIVE: Despite the recommendation that patients with chronic lung diseases--many of whom receive corticosteroids--receive annual influenza vaccination, it is not known whether corticosteroids influence antibody response to influenza vaccine in this population. The purpose of this study was to assess whether patients with pulmonary conditions receiving long-term corticosteroid therapy develop an adequate antibody response. DESIGN: We prospectively studied 39 consecutive candidates for influenza vaccination, 25 of whom were receiving corticosteroids for underlying lung diseases. Patients with immunosuppression besides corticosteroids were excluded. Serum samples were obtained prior to and 1 month after vaccination with inactivated trivalent influenza vaccine and assayed for antibodies to the three strains using a hemagglutination inhibition assay. No patients had any intercurrent illness compatible with influenza during the study period and patients receiving corticosteroids continued treatment with them during this time. RESULTS: A fourfold rise in antibody titer at 1 month to at least one component was seen in 21 of 25 (84%) of corticosteroid-treated patients, which was similar to patients not receiving corticosteroids (11/14, 79%). There was no corticosteroid-antibody, dose-response relationship. CONCLUSIONS: Patients with pulmonary conditions receiving corticosteroids can generate an adequate antibody response to killed influenza virus vaccine. Long-term therapy with corticosteroids should not preclude influenza vaccination in patients with chronic pulmonary diseases who are deemed vaccine candidates.

Interleukin 12 administration enhances Th1 activity but delays recovery from influenza A virus infection in mice.

Interleukin 12 (IL-12) directs the differentiation of undifferentiated T helper (Th0) cells to T helper type 1 (Th1) cells and induces a cell-mediated immune response. To evaluate the effect of IL-12 on the course of influenza A virus infection, BALB/c mice were administered a daily intraperitoneal dose of 1000 ng of IL-12 or saline on days -1 to +4 for a total of six treatments. The treatment generally enhanced Th1-mediated responses. IFNgamma lung concentrations were 1193 +/- 275 pg/100 microl in controls and 3693 +/- 745 pg/100 microl in IL-12-treated mice at day 5. IFNgamma levels were undetectable at day 13 in controls and 1335 +/- 220 pg/100 microl in IL-12-treated mice. Cytokine production was also assessed at the single-cell level for mediastinal lymph nodes. IL-12 treatment increased the number of IL-2- and IFNgamma-producing cells and decreased the number of IL-4- and IL-10-producing cells. IL-12 treatment decreased the anti-influenza antibody response, especially anti-influenza IgG1 antibody resulting in an increased IgG2a/IgG1 ratio. Primary pulmonary CTL activity on day 5 was low for both groups (10% specific lysis). Secondary CTL activity at day 11 was higher for control mice than for IL-12-treated mice on day 11 (44 versus 34%), but not on day 13. Despite this overall enhancement of Th1-mediated immune functions, the IL-12 treatment increased severity of the disease. Following infection, control and IL-12-treated mice decreased their body weight to approximately 75% of their initial weight. After day 5, the control mice started to recover, while IL-12-treated mice did not begin recovering until day 9. Pulmonary viral titers were 1.6 +/- 0.3 TCID50 in controls at day 5 compared to 2.4 +/- 0.3 for IL-12-treated mice (P < 0.01). In addition, control mice had significantly less severe inflammation and damage on histologic examination. Serum TNFalpha concentrations, undetectable in control mice, were elevated by IL-12 treatment up to 80 pg/ml at day 5 and decreased to zero at day 13. It is concluded that IL-12 administration to influenza-infected mice induces a switch from a Th2- to a Th1-mediated response, but inhibits recovery probably through induction of TNFalpha.

Absolute peripheral blood lymphocyte count and subsequent mortality of elderly men. The Baltimore Longitudinal Study of Aging.

In this 16-year longitudinal study of 105 healthy elderly men, we analyzed one aspect of immunosenescence--a decline in the absolute number of peripheral blood lymphocytes--with particular reference to its relationship with subsequent mortality. It was found that there was a significantly (P less than .01) lower absolute lymphocyte count (1432 +/- 55/mm3; mean +/- SEM) within three years of death when compared with five years (1719 +/- 89/mm3) or 10 years (1715 +/- 98/mm3) before death. There was no relationship between this decrease in lymphocytes and age at death, smoking status, or prior cardiac illness. Previous cross-sectional studies have yielded conflicting data on age-related decreases in lymphocytes which may have been the result of an unrecognized selection process that either eliminated or included subjects who were close to death.

Disseminated microsporidiosis especially infecting the brain, heart, and kidneys. Report of a newly recognized pansporoblastic species in two symptomatic AIDS patients.

Microsporidia have emerged as important opportunistic AIDS pathogens of the alimentary, respiratory, and urinary tracts. Although nonhuman mammalian microsporidia infections typically include encephalitis, CNS microsporidiosis has not been reported in patients with AIDS. A 33-year-old white male and an 8-year-old black girl presented with seizures and declining mental status. Central nervous system (CNS) imaging studies revealed small peripherally and diffusely enhancing lesions present for at least 2 and 4 months before death, respectively. Both patients expired despite empirical anti-toxoplasma therapy. Their brains contained innumerable soft gray matter lesions that consisted of central areas of necrosis, filled with free spores and spore-laden macrophages, surrounded by microsporidia-infected astrocytes. The complete autopsy of the child also revealed necrotizing and sclerosing cardiac and renal microsporidiosis and infection of the pancreas, thyroid, parathyroids, liver, spleen, lymph nodes, and bone marrow. Infected cells included astrocytes, cardiac myocytes, epithelium, endothelium, vascular smooth muscle cells, hepatocytes, adipocytes, Schwann cells, and macrophages. Light and electron microscopic studies revealed pansporoblastic development within thick-walled sporophorous vacuoles of parasite origin. Although most similar to Pleistophora sp and Thelohania sp, this microsporidian is different from any known species. Microsporidiosis should be considered as the possible cause of a wide range of diseases in AIDS patients, including CNS, cardiac, and renal.

Effect of long-term dietary antioxidant supplementation on influenza virus infection.

This study compared the effect of vitamin E on the course of influenza infection with that of other antioxidants. (In a previous study we showed that short-term vitamin E supplementation significantly decreased pulmonary viral titer in influenza-infected old mice). Eighteen-month-old C57BL/6NCrlBR mice were fed one of the following semisynthetic diets for 6 months: control, vitamin E supplemented, glutathione supplemented, vitamin E and glutathione supplemented, melatonin supplemented, or strawberry extract supplemented. After influenza virus challenge, mice fed vitamin E-supplemented diet had significantly lower pulmonary viral titers compared to those fed the control diet (10(2.6) vs 10(4.0), p < .05) and were able to maintain their body weight after infection (1.8+/-0.9 g weight loss/5 days postinfection in vitamin E group vs 6.8+/-1.4 g weight loss/5 days postinfection in control group, p < .05). Other antioxidants did not have a significant effect on viral titer or weight loss. There was a significant inverse correlation of weight loss with food intake (r = -.96, p < .01), indicating that the observed weight changes were mainly due to decreased food intake. Pulmonary interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha levels increased significantly postinfection. The vitamin E group had lower lung IL-6 and TNF-alpha levels following infection compared to the control group. In addition, there was a significant positive correlation between weight loss and lung IL-6 (r = .77, p < .01) and TNF-alpha (r = .68, p < .01) levels. Because IL-6 and TNF-alpha have been shown to contribute to the anorexic effect of infectious agents, the prevention of weight loss by vitamin E might be due to its reduced production of IL-6 and TNF-alpha following infection. Thus, among the antioxidants tested, only vitamin E was effective in reducing pulmonary viral titers and preventing an influenza-mediated decrease in food intake and weight loss. Other dietary antioxidant supplementations that reduced one or more measures of oxidative stress (4-hydroxynonenal, malondialdehyde, and hydrogen peroxide) did not have an effect on viral titer, which suggests that, in addition to its antioxidant activity, other mechanisms might be involved in vitamin E's beneficial effect on lowering viral titer and preventing weight loss.

Long-term urinary tract catheterization.

As the nursing home population expands, the number of patients exposed to the risks of chronic indwelling urinary catheters will increase. The physician must therefore be familiar with the characteristic findings in such patients and be able to recognize complications as they arise. Mechanical or local problems, such as asymptomatic bacteriuria, catheter blockage, nondeflatable balloon, and chronic cystitis, are very common. Further studies are needed to define optimum measures to control these problems. The clinician must be aware that pyuria and bacteriuria are universal and not helpful in diagnosis of infection in this population. Use of chronic antibiotics is not recommended and there is no evidence to support elaborate daily care regimens, such as antibiotic ointments or irrigations. Careful consideration of the indications for catheter use on a long-term basis may reduce the population at risk. Physician awareness of the possibility of life-threatening complications, such as squamous cell carcinoma, bacteremia, and bladder perforation, can help avoid serious consequences of the use of urinary drainage devices.

Surgical issues in the management of the HIV-infected patient.

As of 1992, approximately 1,000,000 Americans are infected with HIV. The natural history of the illness includes a relatively long latent period (about 10 years) between infection and development of AIDS. Surgeons are called on to participate in the management of these patients, usually for diagnostic biopsies, supportive measures, or intraabdominal events. Precautions and safe surgical practices will minimize the risk of HIV transmission from patient to surgeon (or surgeon to patient).

Modeling the relationship between clinical, microbiologic, and immunologic parameters and alveolar bone levels in an elderly population.

A cross-sectional periodontal study of 74 subjects aged 65 to 75 years was performed. Clinical data were collected and related to microbiological and immunological data. A statistical model (step-wise multiple regression) of factors related to bone loss was created initially using clinical data only; then by adding either the microbiologic or immunologic data; and then by using clinical, microbiologic, and immunologic data together. When only clinical data were considered, three factors were found to have significant positive correlations with bone loss. Tooth mobility accounted for 17% of the variability in the alveolar bone level measurements, probing depth for 12%(r2), and plaque index for 3%, for a total of 32% of the variability explained by these clinical factors. Tooth mobility and probing depth were clinical factors which remained significant in the model when the microbiological data were also considered. As percentages of the total cultivable microbiota, E. corrodens (r2 = 14%) and black-pigmenting Prevotella intermedia (r2 = 4%) correlated positively with alveolar bone loss. The addition of the microbiologic data only increased the r2 to 33%. When immunological data were considered with the clinical data, pocket depth and tooth mobility were the clinical parameters which remained in the model. IgG antibody levels to P. gingivalis W83 and/or 381 (r2 = 24%) A. actinomycetemcomitans 627 (r2 = 2%) were the significant immunologic measures having a positive correlation with bone loss. Anti-F. nucleatum levels had a significant negative correlation. A total of 50% of the variability in alveolar bone level was accounted for in the model by the addition of specific serum antibody levels to subgingival plaque microorganisms. When clinical, microbiological, and immunological measurements were all considered together, antibody to P. gingivalis W83 and/or 381 (r2 = 42%), percentage of B-lymphocytes (r2 = 3%), probing depth (r2 = 4%), anti-E. corrodens levels (r2 = 2%), and anti-P. gingivalis 33277 levels (r2 = 4%) all had significant positive correlation with loss of alveolar bone. The number of enteric bacteria, anti-F. nucleatum levels, and anti-P. intermedia levels each had a significant negative correlation with alveolar bone heights. The r2 for this model was 75%. These results indicated that antibody levels to subgingival plaque microorganisms and tooth mobility were the best predictors of bone loss in the elderly patients tested in this study.

Disseminated Curvularia infection. Additional therapeutic and clinical considerations with evidence of medical cure.

A previously reported case of cerebral infection due to Curvularia lunata is more fully described. Medical cure was apparently achieved after 30 months' treatment with amphotericin B. Success was achieved only when the drug was given in a dose of 40 mg, three times per week, and was continued for six months after enhanced computed tomographic scans no longer showed cerebral lesions. Immunologic studies suggested the infection was accompanied by an unexplained defect in cell-mediated immunity.

Sepsis.

Septic shock is associated with a very high mortality in elderly patients. This is likely due to the age-related anatomic and physiologic changes and the presence of comorbid diseases. Medical management of patients with septic shock consists of antibiotics, fluids, vasopressors, and careful monitoring. Judicious use of antiendotoxin monoclonal antibodies may be a beneficial adjunctive therapy.

Failure of a prospective trial to detect cytomegalovirus retinitis after initiation of highly active antiretroviral therapy.

Thirty-one patients with AIDS with CD4+ T-cell counts of less than 75/mm3 were enrolled in a prospective study to determine the incidence of cytomegalovirus (CMV) retinitis and changes in CD4+ T-cell counts and viral loads following initiation of highly active anti-retroviral therapy (HAART). Patients were assessed using an Amsler grid, a visual field test, a questionnaire, and direct and indirect funduscopy. Only one patient developed an opportunistic infection, and the majority of patients had a threefold decrease in their viral loads and an increase in CD4+ T-cell counts within 2 months of initiating HAART. These findings support the belief that recent therapies modify the natural history of HIV infection and that new clinical approaches will be needed to address the changing profile of HIV/AIDS patients. None of our patients developed CMV retinitis. The findings add to those of other researchers, and suggest that if CMV retinitis does develop after HAART, it is an unusual finding that may be due to preexisting, subclinical retinitis rather than failure of HAART to reconstitute full immune cell recovery.