Alterations in the human immune response to the hepatitis B vaccine among the elderly

Effects of heat-killed Enterococcus faecalis T-110 supplementation on gut immunity, gut flora, and intestinal infection in naturally aged hamsters

Infectious diseases are a threat to elderly individuals, whose immune systems weaken with age. Among the various infectious diseases, Clostridium difficile infection is associated with a high rate of mortality in elderly individuals and is a serious health problem worldwide, owing to the increasing infection rates. Probiotic use has been proposed as an effective countermeasure for C. difficile infection. The aim of this study was to evaluate the effects of heat-killed Enterococcus faecalis T-110 on intestinal immunity, intestinal flora, and intestinal infections, especially C. difficile infections, in naturally ageing animals, for extrapolating the results to elderly human subjects. Twenty female hamsters were randomly distributed into two groups. Group 1 was fed a basal diet and group 2 was fed a basal diet supplemented with heat-killed E. faecalis for 7 days. Heat-killed E. faecalis T-110 improved the gut immunity and microflora, especially Clostridium perfringens and C. difficile, in naturally aged hamsters. Therefore, heat-killed E. faecalis T-110 use may be a countermeasure against age-related immune dysfunction and intestinal infections, especially C. difficile infection, in elderly humans. However, further investigation in this regard is needed in humans.

Live Attenuated Leishmania donovani Centrin Knock Out Parasites Generate Non-inferior Protective Immune Response in Aged Mice against Visceral Leishmaniasis

Background

Visceral leishmaniasis (VL) caused by the protozoan parasite Leishmania donovani causes severe disease. Age appears to be critical in determining the clinical outcome of VL and at present there is no effective vaccine available against VL for any age group. Previously, we showed that genetically modified live attenuated L. donovani parasites (LdCen-/-) induced a strong protective innate and adaptive immune response in young mice. In this study we analyzed LdCen-/- parasite mediated modulation of innate and adaptive immune response in aged mice (18 months) and compared to young (2 months) mice.

Methodology

Analysis of innate immune response in bone marrow derived dendritic cells (BMDCs) from both young and aged mice upon infection with LdCen-/- parasites, showed significant enhancement of innate effector responses, which consequently augmented CD4⁺ Th1 cell effector function compared to LdWT infected BMDCs in vitro. Similarly, parasitized splenic dendritic cells from LdCen-/- infected young and aged mice also revealed induction of proinflammatory cytokines (IL-12, IL-6, IFN-γ and TNF) and subsequent down regulation of anti-inflammatory cytokine (IL-10) genes compared to LdWT infected mice. We also evaluated in vivo protection of the LdCen-/- immunized young and aged mice against virulent L. donovani challenge. Immunization with LdCen-/- induced higher IgG2a antibodies, lymphoproliferative response, pro- and anti-inflammatory cytokine responses and stimulated splenocytes for heightened leishmanicidal activity associated with nitric oxide production in young and aged mice. Furthermore, upon virulent L. donovani challenge, LdCen-/- immunized mice from both age groups displayed multifunctional Th1-type CD4 and cytotoxic CD8 T cells correlating to a significantly reduced parasite burden in the spleen and liver compared to naïve mice. It is interesting to note that even though there was no difference in the LdCen-/- induced innate response in dendritic cells between aged and young mice; the adaptive response specifically in terms of T cell and B cell activation in aged animals was reduced compared to young mice which correlated with less protection in old mice compared to young mice.

Conclusions

Taken together, LdCen-/- immunization induced a significant but diminished host protective response in aged mice after challenge with virulent L. donovani parasites compared to young mice.

Visceral leishmaniasis (VL) is caused by the protozoan parasite Leishmania donovani. There is no effective vaccine available against VL for any age group and importantly, there are no previous studies regarding immune responses against experimental Leishmania vaccines tested in aged animals. We have reported earlier that immunization with a live attenuated L. donovani parasites (LdCen-/-) induced protective immune response in young animals viz, mice, hamsters and dogs. In this study we analyzed LdCen-/- mediated modulation of innate and adaptive responses in aged mice and compared to young mice. We observed that LdCen-/- infected dendritic cells from young and aged mice resulted in enhanced innate effector functions compared to LdWT parasites both in vitro and in vivo. Further, upon virulent challenge, LdCen-/- immunized young and aged mice displayed protective Th1 immune response which correlated with a significantly reduced parasite burden in the visceral organs compared with naïve challenged mice. Although there was no difference in the LdCen-/- induced dendritic cell response between aged and young mice; adaptive response in aged was reduced, compared to young which correlated with less protection in aged compared to young mice. This study supports the potential use of LdCen-/- as vaccine candidate across all age groups against VL.

Hepatitis B and elders: An underestimated issue

As the world's population becomes older, the burden of hepatitis B virus in elderly has to be considered. The liver changes with aging and its function is eventually altered. The prevalence of hepatitis B virus is paradoxically more important in elderly in areas having vaccination programs, because of a loosening of the prevention in older patients. Some differences in hepatitis B presentation must be enhanced in elderly: lower spontaneous hepatitis B surface antigen clearance after a recent contamination, major risk of cirrhosis and hepatocarcinoma. Acute hepatitis B seems to be more often symptomatic, with a great risk of chronicity. Hepatocarcinoma linked to hepatitis B virus has a higher prevalence and a different presentation in elderly. Its treatment is the same as in younger people but is less often possible. Liver transplantation is contraindicated after 70 years old. Hepatitis B treatment panel is the same as in younger people (pegylated interferon, nucleoside or nucleotide agents). It gives identical results with no particular adverse events if the precautions for use are followed. Vaccination is less efficient, as in immunocompromised patients, and needs specific protocols.

Heterogeneity in thymic emigrants: implications for thymectomy and immunosenescence

The development of mature, antigen-inexperienced (naive) T cells begins in the thymus and continues after export into the periphery. Post-thymic maturation of naive T cells, in humans, coincides with the progressive loss of markers such as protein tyrosine kinase 7 (PTK7) and platelet endothelial cell adhesion molecule-1 (CD31). As a consequence, subpopulations of naive T cells can be recognised raising questions about the processes that give rise to the loss of these markers and their exact relationship to recent thymic emigrants (RTE). Here, we combine a mathematical survival analysis approach and data from healthy and thymectomised humans to understand the apparent persistence of populations of ‘veteran’ PTK7⁺T cells in thymectomised individuals. We show that a model of heterogeneity in rates of maturation, possibly linked to natural variation in TCR signalling thresholds or affinity for self-antigens, can explain the data. This model of maturation predicts that the average post-thymic age of PTK7⁺T cells will increase linearly with the age of the host suggesting that, despite the immature phenotype, PTK7⁺cells do not necessarily represent a population of RTE. Further, the model predicts an accelerated increase in the average post-thymic age of residual PTK7⁺T cells following thymectomy and may also explain in part the prematurely aged phenotype of the naive T cell pool in individuals thymectomised early in life.

Immunoprotective effects of oral intake of heat-killed Lactobacillus pentosus strain b240 in elderly adults: a randomised, double-blind, placebo-controlled trial

Oral intake of Lactobacillus pentosus strain b240 (b240) has been shown to enhance the secretion of salivary secretory IgA in elderly adults. However, its clinical benefits remain to be determined. We tested the hypothesis that b240 exerts a protective effect against the common cold in elderly adults. The design of the present study was a randomised, double-blind, placebo-controlled trial (RCT) with parallel three-group comparison. For this purpose, 300 eligible elderly adults were randomly allocated to one of three groups, namely a placebo, low-dose or high-dose b240 group. Participants in the low-dose and high-dose b240 groups were given tablets containing 2 × 10(9) or 2 × 10(10) cells, respectively, of heat-killed b240, while those in the placebo group were given tablets without b240. Each group consumed their respective tablets once daily for 20 weeks. The common cold was assessed on the basis of a diary. Change in quality of life was evaluated using the SF-36. Of the total participants, 280 completed the 20-week RCT. The accumulated incidence rate of the common cold was 47·3, 34·8 and 29·0 % for the placebo, low-dose b240 and high-dose b240 groups, respectively (P for trend = 0·012). Lower incidence rates were consistently observed throughout the experimental period in the b240 groups (log-rank test, P= 0·034). General health perception, as determined by the SF-36®, dose-dependently increased in the b240 groups ( P <0·025). In conclusion, oral intake of b240 significantly reduced the incidence rate of the common cold in elderly adults, indicating that b240 might be useful in improving resistance against infection through mucosal immunity.

Viral hepatitis in the elderly

As life expectancy continues to rise, elderly adults represent a rapidly growing proportion of the population. The likelihood of complications of acute and chronic liver disease and overall mortality are higher in elderly populations. Several physiological changes associated with aging, greater prevalence of co-morbid conditions, and cumulative exposure to hepatotropic viruses and environmental hepatotoxins may contribute to worse outcomes of viral hepatitis in the elderly. Although pharmacotherapy for hepatitis B and C continues to evolve, the efficacy, tolerability, and side effects of these agents have not been studied extensively in elderly adults. Immunization against hepatitis A and B in naïve elderly adults is an important public health intervention that needs to be revised and broadened.

Diagnosis and management of chronic liver disease in older people

Chronic liver disease is increasingly prevalent and, as the population ages, geriatricians will see an increasing burden. We present an overview of the investigation and management of older adults with chronic parenchymal liver disease and highlight the potential roles of transjugular intrahepatic portosytemic shunts and orthotopic liver transplantation.

Oral intake of Lactobacillus pentosus strain b240 accelerates salivary immunoglobulin A secretion in the elderly: A randomized, placebo-controlled, double-blind trial

Background

Immunoglobulin A (IgA) secretion in saliva decreases with age and may be the cause of increased vulnerability of the elderly to respiratory infections. The effect of oral intake of lactic acid bacteria on salivary secretory IgA (SIgA) in the elderly has not been reported. The objective of this study was to demonstrate the acceleration of salivary SIgA secretion by oral intake of Lactobacillus pentosus strain b240 (b240) in the elderly.

Results

A total of 80 healthy elderly individuals were randomly allocated to either an intervention (i.e., b240) or a control (i.e., placebo) group. The elderly individuals in the b240 group were given a sterile water beverage (125 mL) containing heat-killed b240 (4 × 10⁹ cells), while those in the placebo group were given only a sterile water beverage (125 mL); both groups received their respective beverages once daily for 12 weeks. Saliva was collected before initiation of the study and every 2 weeks thereafter. Saliva flow rate and SIgA concentration were determined, and the SIgA secretion rate was calculated. The mean salivary SIgA secretion rate in the b240 group steadily increased until week 4 (exhibiting a 20% elevation relative to that at week 0), and then remained stable until week 12. Changes in SIgA secretion rate over the intervention period were significantly greater in the b240 group than in the placebo group. The treatment groups exhibited no significant differences in adverse events.

Conclusions

Oral intake of L. pentosus strain b240 for 12 weeks significantly accelerated salivary SIgA secretion, thereby indicating its potential utility in the improvement of mucosal immunity and resistance against infection in the elderly.

Cell-intrinsic defects in the proliferative response of antiviral memory CD8 T cells in aged mice upon secondary infection

Although previous studies have demonstrated delayed viral clearance and blunted effector T cell responses in aged mice during infection, memory CD8 T cells and especially secondary responses have received less attention. In this study, we show that modest differences in the number of memory CD8 T cells formed in aged versus young animals were associated with altered memory CD8 T cell differentiation. Aged immune mice had increased morbidity and mortality upon secondary viral challenge, suggesting changes in T cell immunity. Indeed, virus-specific memory CD8 T cells from aged mice showed substantially reduced proliferative expansion upon secondary infection using multiple challenge models. In addition, this defect in recall capacity of aged memory CD8 T cells was cell-intrinsic and persisted upon adoptive transfer into young mice. Thus, the poor proliferative potential of memory T cells and altered memory CD8 T cell differentiation could underlie age-related defects in antiviral immunity.

Differential impact of ageing on cellular and humoral immunity to a persistent murine gamma-herpesvirus

Background

Oncogenic γ-herpesviruses establish life-long infections in their hosts and control of these latent infections is dependent on continual immune surveillance. Immune function declines with age, raising the possibility that immune control of γ-herpesvirus infection becomes compromised with increasing age, allowing viral reactivation and/or increased latent load, both of which are associated with the development of malignancies.

Results

In this study, we use the experimental mouse γ-herpesvirus model, γHV68, to investigate viral immunity in aged mice. We found no evidence of viral recrudescence or increased latent load in aged latently-infected mice, suggesting that effective immune control of γ-herpesvirus infection remains intact with ageing. As both cellular and humoral immunity have been implicated in host control of γHV68 latency, we independently examined the impact of ageing on γHV68-specific CD8 T cell function and antibody responses. Virus-specific CD8 T cell numbers and cytolytic function were not profoundly diminished with age. In contrast, whereas ELISA titers of virus-specific IgG were maintained over time, there was a progressive decline in neutralizing activity. In addition, although aged mice were able to control de novo acute infection with only slightly delayed viral clearance, serum titers of neutralizing antibody were reduced in aged mice as compared to young mice.

Conclusion

Although there is no obvious loss of immune control of latent virus, these data indicate that ageing has differential impacts on anti-viral cellular and humoral immune protection during persistent γHV68 infection. This observation has potential relevance for understanding γ-herpesvirus immune control during disease-associated or therapeutic immunosuppression.

Effects of aging on the adaptive immune response to respiratory virus infections

Severe acute respiratory disease caused by respiratory virus infections in individuals aged 65 years and older and in high-risk adults, such as those with chronic cardiopulmonary disorders, is associated with increased hospitalization and mortality rates. Epidemiological studies have identified influenza virus and respiratory syncytial virus as the most frequent causes of virus-induced respiratory disease in elderly and high-risk adults. Studies in both humans and animal models have established fundamental defects in cell-mediated and humoral immune responses in aged individuals. However, it is not well understood how age specifically alters the immune response to respiratory pathogens. In this review, we will focus our discussion on the major causative agents of severe respiratory virus infections in elderly and high-risk adults and the age-associated defects in the immune response that probably contribute to the increased disease severity observed in these populations.

Prospects for developing an effective particle-mediated DNA vaccine against influenza

Vaccine strategies capable of conferring broad protection against both seasonal and pandemic strains of influenza are urgently needed. DNA vaccines are an attractive choice owing to their capacity to induce robust humoral and cellular immune responses at low doses and because they can be developed and manufactured rapidly to more effectively meet the threat of an influenza epidemic or pandemic. Particle-mediated epidermal delivery (PMED), or the gene gun, is a DNA vaccine delivery technology shown to induce protective levels of antibody and T-cell responses in animals and humans against a wide variety of diseases, including influenza. This review focuses on current advances toward the development of an effective PMED DNA vaccine against influenza, including strategies to enhance vaccine immunogenicity, the potential for PMED-based DNA vaccines to improve protection in the vulnerable elderly population, and the prospects for a vaccine capable of providing cross-protection against both seasonal and pandemic strains of influenza.

T-cell immunosenescence: lessons learned from mouse models of aging

It is well established that increasing age is associated with a decreased capacity of the immune system to mediate effective immune responses to vaccination and invading pathogens. Because of the inherent limitations of conducting experiments in humans, much of what we have learned is owed to the utility of experimental mouse models of aging. Recent studies performed in the mouse have demonstrated mechanisms responsible for age-related declines in the function of CD4(+) and CD8(+) cells. This review describes key findings regarding age-related defects in T-cell function and discusses the impact these defects have on vaccine efficacy and immunity.

Vaccination in the elderly: an immunological perspective

Successful vaccination of the elderly against important infectious pathogens that cause high morbidity and mortality represents a growing public health priority. Building on the theme of aging and immunosenescence, we review mechanisms of human immunosenescence and the immune response to currently licensed vaccines. We discuss the difficulties in identifying the risk factors that, in addition to aging, cause immunosenescence and address the relative paucity of vaccine studies in the elderly. We conclude that vaccine responses are blunted in the elderly compared with that of healthy young adults. However, it is also clear that our understanding of the mechanisms underlying immunosenescence is limited and much remains to be learned to improve the effectiveness of next generation vaccines.

Effects of aging on T cell function

Immunosenescence influences many components of the immune system. Most importantly, profound changes in T cell function are evident in older individuals. The impact of aging on specific T cell subsets has been difficult to examine, but recent advances in murine model systems and new insights into T cell function have allowed for the more precise examination of how T cell responses change with aging. Importantly, recent studies have shown that age-related enhancement of both Th17 generation and regulatory T cell function may contribute to significant changes in immune function. In this review, we summarize the current views on how aging influences the factors that impact T cell function and how this can affect the immune response to infections, vaccinations, and tumors.

Proinflammatory adjuvants enhance the cognate helper activity of aged CD4 T cells

Age-related declines in humoral responses contribute to the reduced efficacy of vaccines in older populations. Using an adoptive transfer model, we have shown that age-related intrinsic declines in CD4 T cell function contribute significantly to the reduced humoral responses observed with aging, resulting in reduced B cell expansion and differentiation as well as reduced IgG production. In this current study, we show that the helper function of aged CD4 T cells can be enhanced using a TLR-binding adjuvant or an adjuvant containing proinflammatory (PI) cytokines. The helper function of aged CD4 T cells was also enhanced when PI cytokines were added during in vitro CD4 effector generation. Enhanced helper activity resulted in improved expansion and differentiation of B cells and affinity maturation of IgG. PI cytokines also induced significant production of effector cytokines, including IL-4, IFN-gamma, IL-17, and IL-21, by both young and aged CD4 T cells. Importantly, we also show that proinflammatory adjuvants can significantly enhance the humoral response in intact aged animals. We propose that one of the mechanisms involved in the ability of adjuvants to enhance both young and aged T cell responses includes driving multifaceted T cell differentiation and production of multiple cytokines by responding CD4 T cells.

Implicações da imunossenescência na vacinação de idosos

Resumo A prevalência de indivíduos idosos em relação aos indivíduos jovens compreende um quadro comum na população mundial. Estima-se que, em 2050, cerca de 22% da população mundial será constituída por indivíduos idosos. No Brasil, o número de idosos (≥ 60 anos de idade) passou de 3 milhões em 1960 para 7 milhões em 1975 e 14 milhões em 2002 (um aumento de 500% em 40 anos), e estima-se que alcançará 32 milhões em 2020. Este fenômeno se deve ao advento de drogas antibacterianas, a vacinações em larga escala e a outros avanços no tratamento médico. Contudo, a eficácia de uma vacina depende, sobretudo, da habilidade dos indivíduos para exibir uma resposta imune adequada. Assim, esta revisão apresenta os principais efeitos da imunossenescência na resposta imune a uma vacina. Além disto, discute algumas estratégias que aumentam os níveis de proteção das imunizações neste grupo etário. A compreensão dos fatores envolvidos na geração de uma resposta imunológica durante a senescência e a introdução de estratégias que melhoram a eficácia de vacinas nos indivíduos idosos reduz a incidência e a severidade de doenças infecciosas, tendo forte impacto na qualidade de vida destes indivíduos.

Efficacy of lamivudine therapy in elderly patients with chronic hepatitis B infection

BACKGROUND

The aim of this study was to evaluate the efficacy of lamivudine therapy in elderly patients with chronic HBV infection.

METHODS

Patients aged >or=60 years (n = 40) received lamivudine monotherapy between February 1995 and September 2005 at Toranomon Hospital. We compared the efficacy of lamivudine therapy in these patients and in 639 patients aged <60 years, including 80 patients aged <60 years matched for sex, hepatitis B e antigen (HBeAg) status, and hepatitis B virus (HBV) DNA level.

RESULTS

The rates of normalization of alanine aminotransferase (ALT) level in 40 patients aged >or=60 years and 639 patients aged <60 years were 85% versus 76%, and 86% versus 73% at 1 and 3 years, respectively. The respective rates of loss of HBV-DNA were 74% versus 74%, and 76% versus 68% at 1 and 3 years. The respective cumulative emergence rates of the YMDD mutant were 16% and 17% at 1 year, and 46% and 49% at 3 years. In 80 patients <60 years old matched for sex, HBeAg status, and HBV-DNA level, the rates of normalization of the ALT level and loss of HBV-DNA were similar to those in the 639 patients aged <60 years. The emergence rate of YMDD mutants in patients aged >or=60 years were similar to those in matched patients aged <60 years. Multivariate analyses identified low serum bilirubin (<1 mg/dl) as an independent factor associated with the emergence of the YMDD motif mutation in patients aged >or=60 years.

CONCLUSIONS

Our results suggest that treatment with lamivudine is both well tolerated and efficacious in elderly patients with chronic HBV infection.

Aging and CD8+ T cell immunity to respiratory virus infections

The capacity of the immune system to mediate effective immune responses to pathogens declines with age. In the case of immune responses to newly encountered antigens, several studies have demonstrated that this decline reflects both a loss of naïve T cells and changes in the repertoire and function of these cells over time. However, comparatively little is known about the impact of age on established memory T cells pools. Here we discuss age-related changes in memory CD8(+) T cell pools elicited by influenza and parainfluenza viruses and the impact of these changes on immunity in general.

Number of CD4+ cells and location of forkhead box protein P3-positive cells in diagnostic follicular lymphoma tissue microarrays correlates with outcome

PURPOSE

To examine the immune microenvironment in diagnostic follicular lymphoma (FL) biopsies and evaluate its prognostic significance.

PATIENTS AND METHODS

Immunohistochemistry was used to study numbers and location of cells staining positive for immune cell markers CD4, CD7, CD8, CD25, CD68, forkhead box protein P3 (FOXP3), T-cell intracellular antigen-1, and Granzyme B in tissue microarrays of paraffin-embedded, diagnostic lymph node biopsies taken from 59 FL patients who lived less than 5 years (short-survival group; n = 34) and more than 15 years (long-survival group; n = 25).

RESULTS

CD4 and FOXP3 expression were significantly different between the two groups. Samples from the long-survival group were more likely than those from the short-survival group to have CD4+ staining cells and to have FOXP3-positive cells in a perifollicular location.

CONCLUSION

This study has identified differences in immune cell composition of the diagnostic FL lymph node immune microenvironment and these have the potential for use as prognostic biomarkers in a routine histopathology setting.

Why aging T cells fail: implications for vaccination

The decline in CD4⁺ T cell function with aging contributes to reduced vaccine efficacy. In this commentary, we discuss the factors leading to age-related changes in T cell function and propose how they may be overcome to enhance vaccine efficacy for the elderly.

Immunity and age: living in the past?

Increasing age is associated with a decreasing ability to mediate effective immune responses to newly encountered antigens. It is generally believed that this reflects the age-associated decline in the number, repertoire and function of available naive T cells. Here, we propose that naive T cells become increasingly irrelevant to the immune system, and that responses to newly encountered antigens are progressively dominated by cross-reactive memory T cells as the individual ages. In addition, we propose that the majority, if not all, of the response to newly encountered antigens in the elderly is mediated by cross-reactive memory T cells. This predicts highly stochastic responses to new infections that should vary between individuals, and has important implications for vaccination strategies in the elderly.

Immunization of aged mice with a pneumococcal conjugate vaccine combined with an unmethylated CpG-containing oligodeoxynucleotide restores defective immunoglobulin G antipolysaccharide responses and specific CD4+-T-cell priming to young adult levels

Polysaccharide (PS)-protein conjugate vaccines, in contrast to purified PS vaccines, recruit CD4+-T-cell help and restore defective PS-specific humoral immunity in the immature host. Surprisingly, in the immunocompromised, aged host, anti-PS responses to conjugate vaccines are typically no better than those elicited by purified PS vaccines. Although aging leads to defects in multiple immune cell types, diminished CD4+-T-cell helper function has recently been shown to play a dominant role. We show that in response to immunization with purified pneumococcal capsular PS serotype 14 (PPS14) in saline, the T-cell-independent immunoglobulin G (IgG) anti-PPS14 response in aged mice was comparable to that in young mice. In contrast, the T-cell-dependent IgG anti-PPS14 response to a soluble conjugate of PPS14 and pneumococcal surface protein A (PspA) (PPS14-PspA) in saline was markedly defective. This was associated with defective priming of PspA-specific CD4+ T cells. In contrast, immunization of aged mice with PPS14-PspA combined with an unmethylated CpG-containing oligodeoxynucleotide (CpG-ODN) restored IgG anti-PPS14 responses to young adult levels, which were substantially higher than those observed using purified PPS14. This was associated with enhanced PspA-specific CD4+-T-cell priming. Similarly, intact Streptococcus pneumoniae capsular type 14, which contains Toll-like receptor (TLR) ligands, also induced substantial, though modestly reduced, T-cell-dependent (TD) IgG ant-PPS14 responses in aged mice. Spleen and peritoneal cells from aged and young adult mice made comparable levels of proinflammatory cytokines in response to CpG-ODN, although cells from aged mice secreted higher levels of interleukin-10. Collectively, these data suggest that inclusion of a TLR ligand, as an adjuvant, with a conjugate vaccine can correct defective TD IgG anti-PS responses in elderly patients by augmenting CD4+-T-cell help.

Antibody Quality in Old Age

There is very little change in the quantity of antibodies people produce, of any isotype, with age. However, there is a change in the quality of the antibody response. Older people produce fewer antibodies that are specific for the activating pathogen or vaccine. At the same time, the number of nonspecific antibodies increases. Quite often these antibodies have self-reactivity (e.g., anti-dsDNA). The appearance of these antibodies is not associated with pathogenic autoimmune disease, although it is true that the incidence of some autoimmune diseases increases with age. The authors postulate that the process of antibody affinity maturation is compromised in old age. No evidence was found that the process of hypermutation is compromised with age. However, using graph theory to study the dynamics of a germinal center selection process, a decrease in the extent of selection occurring in the germinal centers of mucosal tissue was observed with age. This is a tissue-specific phenomenon because the decrease was not seen in the germinal centers of spleen. Because selection of highly specific cells in the germinal center depends on a number of factors (number and quality of founder cells, help from T cells, and follicular dendritic cells) these need to be investigated further to determine what is needed to improve the affinity mutation process.

CD4 T cell-independent antibody response promotes resolution of primary influenza infection and helps to prevent reinfection

It is generally believed that the production of influenza-specific IgG in response to viral infection is dependent on CD4 T cells. However, we previously observed that CD40-deficient mice generate influenza-specific IgG during a primary infection, suggesting that influenza infection may elicit IgG responses independently of CD4 T cell help. In the present study, we tested this hypothesis and show that mice lacking CD40 or CD4 T cells produce detectable titers of influenza-specific IgG and recover from influenza infection in a manner similar to that of normal mice. In contrast, mice completely lacking B cells succumb to influenza infection, despite the presence of large numbers of functional influenza-specific CD8 effector cells in the lungs. Consistent with the characteristics of a T-independent Ab response, long-lived influenza-specific plasma cells are not found in the bone marrow of CD40-/- and class II-/- mice, and influenza-specific IgG titers wane within 60 days postinfection. However, despite the short-lived IgG response, CD40-/- and class II-/- mice are completely protected from challenge infection with the same virus administered within 30 days. This protection is mediated primarily by B cells and Ab, as influenza-immune CD40-/- and class II-/- mice were still resistant to challenge infection when T cells were depleted. These data demonstrate that T cell-independent influenza-specific Ab promotes the resolution of primary influenza infection and helps to prevent reinfection.

Homeostasis and the age-associated defect of CD4 T cells

Survival and homeostatic division of naive CD4 T cells is regulated by the cellular and non-cellular milieu and together these processes ensure that a population of naive CD4 T cells persists into old age. However, the naive CD4 T cells from aged animals show reduced IL-2 production, proliferation, helper function and effector generation and memory function. We explore here whether the age-related defects in naive CD4 T cells are due to the aged environment from which they come or to intrinsic defects that are caused by homeostasis and their long lifespan.

The effect of age on the cognate function of CD4+ T cells

With increasing age, the ability to produce protective antibodies in response to immunization declines, resulting in reduced efficacy of vaccination. We have examined how reductions in CD4(+) T-cell function contribute to reduced humoral responses, using a model that allows us to compare identical numbers of antigen-specific naive T cells from young and aged T-cell receptor transgenic mice. Naive cells from aged mice exhibit reduced responses, both in vitro and in vivo. In vitro, responses of aged T cells can be enhanced by addition of interleukin (IL)-2. In vivo, using an adoptive transfer model with young hosts, naive cells from aged mice exhibit significant reductions in cognate helper function, leading to reduced B-cell expansion and differentiation. These age-related defects could be overcome by prior in vitro T helper 2 effector generation with aged T cells. This improvement in cognate function of the aged effectors may be related to the enhancement of CD154 expression, which occurs on aged T cells in the presence of exogenous IL-2. We also found no difference in B-cell expansion and differentiation when young cells were transferred to young or aged hosts. Our results indicate that age-related reductions in humoral responses are mainly due to defects in the cognate helper function of naive CD4(+) T cells from aged individuals.

Age-related defects in CD4 T cell cognate helper function lead to reductions in humoral responses

With increasing age, the ability to produce protective antibodies in response to immunization declines, leading to a reduced efficacy of vaccination in the elderly. To examine the effect of age on the cognate function of CD4 T cells, we have used a novel adoptive transfer model that allows us to compare identical numbers of antigen-specific naive T cells from young and aged TCR transgenic (Tg) donors. Upon transfer of aged donor CD4 T cells to young hosts, there was significantly reduced expansion and germinal center (GC) differentiation of the antigen-specific B cell population after immunization. This reduced cognate helper function was seen at all time points and over a wide range of donor cell numbers. In hosts receiving aged CD4 cells, there were also dramatically lower levels of antigen-specific IgG. These age-related defects were not due to defects in migration of the aged CD4 T cells, but may be attributable to reduced CD154 (CD40L) expression. Furthermore, we found that there was no difference in B cell expansion and differentiation or in IgG production when young CD4 T cells were transferred to young or aged hosts. Our results show that, in this model, age-related reductions in the cognate helper function of CD4 T cells contribute significantly to defects in humoral responses observed in aged individuals.

Inflammatory cytokines overcome age-related defects in CD4 T cell responses in vivo

Age-related decreases in immune function are thought to contribute to the reduced efficacy of vaccinations seen in elderly populations. Our previous in vitro studies demonstrated that naive CD4 T cells from aged TCR-transgenic mice proliferate less than young cells and generate poorly functioning effectors due to decreased IL-2 production. In this current study, we show that this age-related defect in CD4 T cell response also occurs in vivo and that it is correlated with reduced NF-kappa B activation. After transfer to young hosts, CD4 T cells from aged transgenic mice proliferate less and produce reduced levels of IL-2 upon immunization with Ag and alum. Introducing a combination of the inflammatory cytokines TNF-alpha, IL-1, and IL-6, or the use of an adjuvant such as CFA that induces these cytokines, markedly enhanced responses of these aged CD4 T cells, so that they proliferated and produced IL-2 similar to young cells. This enhancement is correlated with the enhanced activation of the transcription factor NF-kappa B in aged cells. We suggest that induction of inflammatory cytokines via adjuvants may enhance the efficacy of vaccinations in elderly populations.

CD4 T cell memory derived from young naive cells functions well into old age, but memory generated from aged naive cells functions poorly

Age-related declines in immune function have an impact on both primary and memory responses. In this study, we have examined the ability of naive CD4 T cells from young and aged T cell receptor transgenic mice to establish functional memory. We found that memory cells generated from young CD4 T cells responded well to antigen, even a year after generation, whereas memory cells derived from CD4 T cells from aged mice responded poorly both ex vivo and in vivo. Memory cells generated from aged naive cells proliferate less, produce reduced levels of cytokines, and exhibit reduced cognate helper function, compared with memory cells generated by using young naive cells. These results indicate that it is the age of the naive T cell when it first encounters antigen, rather than the age when it reencounters antigen, that is critical for good memory CD4 T cell function.

Liver disease in the elderly

Despite several morphologic and functional changes that have been described in the aging liver, most relevant studies fail to identify a significant age-related deficit in liver function in humans. One of the important age-related changes is a decrease in regenerative capacity, which may partly explain the impaired recovery after severe viral and toxic injury in the elderly. Nevertheless, livers from older subjects are used successfully for transplantation. Substantial morbidity and mortality in the elderly is attributable to liver diseases, and the number of patients older than 65 years of age with chronic liver disease is increasing rapidly. Although there are no liver diseases specific to advanced age, the presentation, clinical course and management of liver diseases in the elderly may differ in important respects from those of younger individuals.

Hepatitis B immunization of healthy elderly adults: relationship between naïve CD4+ T cells and primary immune response and evaluation of GM-CSF as an adjuvant

The efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) to enhance the primary immune response to hepatitis B vaccine was studied in healthy elderly with young volunteers included as controls in this double-blind, placebo-controlled trial of GM-CSF as an immune adjuvant. Naïve T-helper cells (CD4+CD45RA+) were determined at baseline. Forty-five healthy elderly (average age, 74 years) and 37 healthy young controls (average age, 28 years) were randomized. Hepatitis B vaccine was administered at 0, 1, and 6 months. GM-CSF as a single injection of either 80 microg or 250 microg with the first and second doses of hepatitis B vaccine. In this trial GM-CSF did not enhance antibody responses. However, the antibody responses were dramatically different between these two groups: 35/35 young developed a protective titer versus 19/45 elderly (P < 0.0001). In addition, the mean logarithm of anti-hepatitis B antibody level in the 35 young who completed the study was 3.17 (log mIU/ml) but only 2.21 in the 19 elderly responders (P < 0.0001). Naïve T-helper cells differed significantly between the two groups: the mean percentage of CD4+CD45RA+ T cells was 47.9% versus 35.0% (P < 0.0001) in the young and elderly volunteers respectively. Naïve T cells also differed significantly between elderly who did or did not respond to HBV (39.9% vs. 31.7%, P = 0.039). Using linear regression, age, and percent naive, CD4 T cells were determined to significantly influence the anti-hepatitis B antibody response, but sex and dose of GM-CSF did not. For a two-parameter model: logarithm of antibody titer = (-0.038 x age in years) + (0.031 x % naïve CD4T cells) + 2.68; adjusted r2 = 0.605 and P < 0.0001. However, age had a larger effect than naive CD4 T cells, i.e., in comparing young and elderly groups the log antibody titer decreased by 1.73 due to the increase in age but only 0.40 due to the decrease in naive CD4 T cells. Thus, there was a large effect of age that could not be explained by the quantitative change in the naïve T-helper cells.

Chronic liver disease in the extremely elderly of 80 years or more: clinical characteristics, prognosis and patient survival analysis

BACKGROUND/AIMS

This study aimed to elucidate the clinical characteristics of patients with chronic liver disease aged 80 years or more, especially the factors affecting prognosis and carcinogenesis.

METHODS

A total of 135 patients aged 80 years or above were divided into chronic liver disease without cirrhosis (non-LC) and cirrhosis (LC) groups according to the severity of fibrosis, and the clinical characteristics and prognoses were evaluated.

RESULTS

Seventy-three (54.1%) of 135 patients were in the LC group and 79 patients (58.5%) had hepatitis C virus. Various concomitant diseases were seen in 122 patients (90.4%). Liver-related deaths occurred in only 19 (36.5%) of 52 patients who died during observation, although 28 patients (53.8%) had liver cancer at the time of death. Cumulative survival rates in the non-LC and the LC groups were 85.7% and 58.8% at the 5th year, and 69.4% and 19.4% at the 9th year, respectively. Cumulative liver cancer appearance rates in the non-LC and the LC groups were 1.6% and 6.1% at the 1st year, 12.4% and 19.9% at the 5th year, and 12.4% and 32.0% at the 7th year, respectively. A multivariate Cox regression analysis revealed that the presence of liver cancer (p=0.0001), platelet count (p=0.0242), and fibrotic stage (p=0.0118) were independently associated with survival period, and alfa-fetoprotein (p=0.0194) and bilirubin (p=0.0282) were independently associated with carcinogenesis.

CONCLUSIONS

Cirrhosis is the major risk factor affecting the prognosis. On the other hand, we must pay more attention to concomitant diseases specific to advanced age.

Vitamin E and infectious diseases in the aged

The incidence of infectious diseases, particularly respiratory diseases, increases with age. Age-associated decline in immune function contributes to the increased susceptibility of the aged to infections. Vitamin E supplementation has been shown to improve some aspects of immune function in aged animals and human subjects. The protective effect of vitamin E against viral or bacterial infections in experimentally-challenged young animals has been reported. We investigated the effects of supplementation with vitamin E and other antioxidants on resistance to influenza infection in young and old animals. While vitamin E-supplemented young mice showed only a modest reduction in lung viral titre, vitamin E-supplemented old mice exhibited a highly significant (P < 0.05) reduction in viral lung titre. In subsequent studies, we focused on the mechanism of vitamin E-induced reduction of influenza viral titre. The results of these studies as well as those reported by other investigators on the relationship between vitamin E and infectious diseases will be reviewed.

Role of cytomegalovirus in the T cell changes seen in elderly individuals

The effect of prior cytomegalovirus (CMV) infection on the immune system was evaluated in young and elderly volunteers. Prevalence of IgG antibodies to CMV was higher in the elderly volunteers. In both age groups, there was a strong association with CMV seropositivity and increased number of CD28- CD4 or CD8 T cells, as well as with increased numbers of T cells expressing CD56 or DR. Although these changes have previously been reported to be age-related, they were independent of age when CMV serological status was taken into account. In contrast, both age group and CMV status were important determinants of the total number of T cells, the number of CD8 T cells, and the number of CD8 T cells expressing CD45RA or CD28. These findings indicate that prior infection with CMV, as reflected by CMV serological status, has important effects on T cell subsets and surface markers and must be considered whenever evaluating age-related changes in immunological parameters.

Age-related changes in antibody repertoire: contribution from T cells

The immune system of aged mice produces antibodies that are characterized by low affinity, diminished protection against infections and autoreactivity. It has been shown that these antibodies may be encoded by different immunoglobulin V genes and that the mechanism of somatic hypermutation in the V genes is inefficient. Studies on scid mice reconstituted with B and T cells from donors of different ages suggested that both lymphocyte subsets may contribute to the age-related changes in antibody repertoire. With help provided by T cells from young mice, the response to a hapten, nitrophenyl(acetyl), became gradually dominated by B-cell clones that rearranged a particular germline VH gene (V186.2). However, help from the aged T cells resulted in a heterogeneous response of B cells expressing many different V segments. Analysis of discrete foci of primary antibody-forming cells suggested that the aged T-helper cells are unable to govern the normally-occurring competition between the B-cell clones that have different affinities for the hapten. It is proposed that a signaling disequilibrium from the aged T cells, which provide less efficient help in quantitative terms, supports the growth of low-affinity B cells. This process may be exacerbated due to the apparent hyperactivity of aged B cells to CD40-mediated mitogenic signal.

Viral hepatitis in older adults

The objective of this paper is to review the epidemiology, manifestations, therapy, and prevention of viral hepatitis in older people and to discuss issues of prevention and management. In developed countries a significant portion of the adult population is not immune to Hepatitis A virus (HAV). Morbidity and mortality from HAV infection increases with age. A safe and effective hepatitis A vaccine is available and health authorities should consider immunization early in life and for healthy adults as well as for potential high risk groups such as nursing home residents. Acute hepatitis due to Hepatitis B virus (HBV) is rare in older people and is usually a mild disease. Most older patients with chronic HBV infection who suffer from advanced liver disease have no evidence of ongoing viral replication. Therefore, they are not candidates for interferon therapy. Those with evidence of ongoing viral replication and compensated liver disease should be offered interferon or be included in clinical trials with new antiviral drugs such as lamivudine. Since the response rate to hepatitis B vaccination decreases with age, developing vaccines with greater immunogenicity is crucial. Hepatitis C virus (HCV) is the most frequent cause of acute viral hepatitis in older people. Acute hepatitis C is usually a mild disease in this age group. Because many older patients with chronic HCV infection have compensated liver disease, they could benefit from antiviral therapy. In light of the low response rate to interferon in older patients with chronic hepatitis C and the side effects of the drug, interferon therapy should be reserved for those with the best chance of response. "Combination" antiviral therapy should be on trial for older patients with chronic HCV infection who do not respond to interferon. The recently discovered RNA virus, Hepatitis G (HGV), has been associated with liver disease in older people. It's role in the pathogenesis of liver injury remains to be elucidated.

Immunogenicity of two versus three injections of inactivated hepatitis A vaccine in adults

AIM

To investigate the immunogenicity of two versus three injections of inactivated strain CR326F-derived hepatitis A vaccine in healthy adults.

METHODS

Healthy adult volunteers (n = 105) at Utrecht University Hospital, The Netherlands, were randomly assigned to receive intramuscular injections (deltoid muscle) of 25 Units (U) at 0 and 6 months (group A, n = 53), or at 0, 2 and 6 months (group B, n = 52). Blood was drawn before and at various time points after vaccination for determination of serum antibody to hepatitis A (anti-HAV).

RESULTS

One month after the first injection, the seroconversion rates (> or = 10 mIU/ml, international units) were 88% for group A and 90% for group B. Only 2/ 103 (one in each group) showed IgM anti-HAV. One month after the second injection, seroconversion rates were 100% in both groups. At months 3, 6 and 7, anti-HAV geometric mean titers were significantly different because of the different vaccination schedules, but they were similar at months 1, 2 and 12. The anti-HAV geometric mean titer increase after the second injection was higher when the interval between the two doses was of longer duration. Anti-HAV titers of females were significantly higher than those of males and vaccinees < or = 30 years had higher titers than those > 30 years.

CONCLUSIONS

Two 25 U doses of the vaccine investigated given at 0 and 6 months, induce adequate anti-HAV titers in all adult healthy vaccinees and are as immunogenic as three doses given at 0, 2 and 6 months.

Hepatitis B virus vaccination for older adults

OBJECTIVE

To compare in adults more than 50 years old the tolerability and immunogenicity of vaccination with recombinant hepatitis B surface antigen (HBs) compared with vaccination with recombinant hepatitis B protein PreS2 + S, and to investigate the safety and immunogenicity of a fourth vaccine dose in poor and non-responders.

DESIGN

Randomized, double-blind prospective study.

SETTING

General clinical research center for outpatient evaluation and vaccination.

SUBJECTS

Adults older than age 50 who were in general good health and with no known risk factors for acquiring or serologic evidence of hepatitis B virus infection.

INTERVENTION

Subjects were randomized to receive 10 mcg HBs (Recombivax, Merck, Sharp and Dohme), 12 mcg PreS2 + S, or 24 mcg PreS2 + S vaccine at 0, 1, and 6 months. Poor and non-responders (anti-Hbs < 10 mIU/mL at month 9 and/or 12) were encouraged to receive a fourth vaccine injection.

MEASUREMENTS

Diary records of temperature and local and systemic reactions following each vaccination were maintained by all subjects. Anti-HBs levels were measured by radioimmunoassay before the first injection, at 1, 2, 3, 6, 7, 9, and 12 months after for all subjects, and 1 month after the fourth injection for the group of poor and non-responders.

MAIN RESULTS

Twenty men and nine women (mean age +/- SD, 66 +/- 8.0 years) were enrolled. Ten subjects received HBs vaccine, nine received 12 mcg PreS2 + S vaccine, and 10 received 24 mcg PreS2 + S vaccine. One subject in the HBs group dropped out, and data were analyzed for the remaining 28 subjects. There were no differences in rates of side effects reported by each of the three groups. Overall, minor local adverse reactions occurred in 12 (40%) after at least one of the first three vaccinations. Systemic side effects occurred in five (17%) after the first vaccination, in one after the second, but in none after the third. The 24-mcg PreS2 + S vaccine was not more immunogenic than the HBs vaccine, and the 12-mcg PreS2 + S vaccine was judged inadequate. Nineteen of 22 (86%) poor and non-responders received a fourth vaccination. Minor local adverse reactions were reported by six (32%), and none reported a systemic side effect. For the 12 subjects receiving a fourth injection of HBs or 24 mcg PreS2 + S vaccine, the proportion of responders 1 month following the fourth injection was greater than for 1 month following the third injection (11 of 12 [92%] versus 12 of 19 [63%], respectively, P < .05).

CONCLUSION

For adults more than 50 years of age who have low anti-HBs levels after three vaccine injections, a fourth injection is well tolerated and results in improved immunogenic response.

Ageing alters the competence of the immune system to control parasitic infection

The elderly are more susceptible to infections with various pathogenic organisms that are young-adults or middle-aged individuals. Certain microorganisms that are non-pathogenic in adults may cause serious infections in the elderly. This heightened susceptibility of the elderly is most likely a reflection of the age-associated decline in the competence of the immune system. It appears that the population of T cells is altered with advanced age and, possibly, the efficiency of the monocyte/macrophage cells to destroy microbial invaders declines. There is a small, but compelling, body of literature which shows that the elderly are particularly susceptible to protozoan and metazoan parasites. We have studied the markedly increased severity of infections in aged mice with the mouse-specific Trypanosoma musculi; both the parasite burden and the duration of infection are substantially greater in old compared to young mice. It appears that this difference is due, to a large extent, to the relatively weak ability of aged animals to generate cytokines associated with the TH1 subset of CD4+ T cells; in particular, the weak ability to generate IL-2 and IFN gamma which are involved in the selective expression of curative, parasite-specific antibody of the IgG2a isotype. A striking difference between young and aged mice is in the response of IL-3 producing cells to the parasite infection; IL-3-producers decline during infection in young mice but increase markedly in aged animals. There are several advantages to using T. musculi as a prototype pathogen for studying age-related susceptibility to infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of perceived psychological stress and distress on antibody response to low dose rDNA hepatitis B vaccine

The present study focused on the relationship between psychological stress and immune reaction to a novel antigen. Participants completed questionnaires on daily hassles, psychoneurotic complaints, coping style, and loneliness, 2 and 6 months after the first of a series injections with a low dose recombinant DNA hepatitis B vaccine. Antibody response was determined 7 months after the first vaccination. Based on the psychological questionnaires two different stress measures were calculated: a Stress Index score-month-2 and a Stress Index score-month-6 indicating stress levels experienced at the beginning and at the end of the study respectively. Antibody levels were found to be negatively related with the Stress Index score-month-2. Although the influence of psychological stress reported on month 6 tended to be in the same direction, this effect was not significant. Coping styles and loneliness were not associated with antibody formation. These results suggest that antibody formation to rDNA hepatitis B vaccine is negatively influenced by psychological stress.

Simultaneous active and passive immunization against hepatitis A studied in a population of travellers

Three hundred travellers, seronegative for hepatitis A, were enrolled into this study to evaluate a new inactivated hepatitis A vaccine. Three injections, each containing at least 720 ELISA units, were administered intramuscularly at months 0, 1 and 6. The subjects were distributed into three groups: 100 received vaccine only; 100 received a single injection of immunoglobulin enriched in HAV antibody; and the 100 remaining travellers received the vaccine and immunoglobulin administered simultaneously with the first vaccine dose. In both vaccinated groups, the rate of seroconversion was found to be higher than 90% at month 1, reaching 100% and 97.8% at month 2 in groups 1 and 3, respectively, and 100% at month 7. In the group receiving both vaccine and immunoglobulin, antibody production was somewhat slower and the final titres were, on average, slightly lower than those obtained in the group with the vaccine alone (GMT 2488 and 3614 mIU ml-1 respectively; p = 0.02). The vaccine appeared to be highly immunogenic in all subjects and was also well tolerated. The slight inhibition of antibody production, induced by the concurrent administration of immunoglobulin, does not affect the overall protection afforded by the vaccine. We conclude that simultaneous active and passive hepatitis A immunizations can be recommended.

Impaired primary antibody responses after vaccination against hepatitis B in patients with breast cancer

The response to hepatitis B (HBV) vaccination was studied in 32 breast cancer patients who were HBV antigen- and antibody-negative at the time of diagnosis. Ten of the patients included into the study received radical mastectomy without adjuvant therapy, 15 patients underwent breast-conserving surgery with subsequent irradiation with or without tamoxifen treatment, and 7 patients were treated by modified radical mastectomy plus adjuvant chemotherapy. Eight patients received the first dose of vaccine 3 months after irradiation therapy. Seven patients were first vaccinated 6 months following irradiation therapy. Seven healthy age-matched persons were vaccinated as controls. Antibody response in the patients was significantly delayed. Four weeks after the second vaccination 6 out of 7 controls showed a significant (> 10 IU/ml) HBs antibody titer, while only 6 out of 32 patients responded. In addition, HBs antibody titers were also significantly lower after the second vaccination even in those patients treated with surgery alone, although they were first vaccinated 3 months after surgery and had no residual tumors. This difference disappeared after the second booster immunization, at which time the frequency of significant antibody titers and the levels of HBs antibody titers were comparable between patients and controls. As the population of patients undergoing treatment for breast cancer is increasing, additional studies are needed to determine optimal immunization regimens in this group of patients.

Influence of ageing on antibody formation in vivo after immunisation with the primary T-cell dependent antigen Helix pomatia haemocyanin

The in vivo antibody response to the primary T-cell dependent antigen Helix pomatia Haemocyanin (HPH) was studied, in order to detect the possible presence of a humoral immune deficiency in ageing. The IgG subclass distribution of the specific antibodies was also determined. In order to define a dose of HPH which could be used to discriminate between the responsiveness of healthy and immunocompromised individuals, we first established a dose-response curve for this antigen in 60 healthy young volunteers. Their responses were compared with the responses of a group of patients suffering from end stage renal failure. The patients who were treated with haemodialysis showed a significantly lower IgM, IgG and IgA anti-HPH antibody response after immunisation with a dose of 30 micrograms HPH, which could be restored by increasing the antigen dose. Patients treated with continuous ambulant peritoneal dialysis and a group of elderly persons, selected according to the Senieur protocol, showed no impairment of antibody formation after immunisation with 30 micrograms HPH, but in the non-Senieur elderly the anti-HPH antibody response was significantly lower. Furthermore, Senieur and non-Senieur elderly persons showed a diminished IgG2 anti-HPH antibody formation, whereas in the elderly non-Senieur individuals and in the patients with renal insufficiency, IgG1 and IgG3 anti-HPH antibodies were also diminished. This study clearly shows that the so-called age-associated immune deficiency can be the result of disease and is not necessarily due to the ageing process itself.