Skin reactivity to Candida and streptokinase-streptodornase antigens in normal pediatric subjects: influence of age and acute illness

Overview of Infections in the Immunocompromised Host

Understanding the components of the immune system that contribute to host defense against infection is key to recognizing infections that are more likely to occur in an immunocompromised patient. In this review, we discuss the integrated system of physical barriers and of innate and adaptive immunity that contributes to host defense. Specific defects in the components of this system that predispose to particular infections are presented. This is followed by a review of primary immunodeficiency diseases and secondary immunodeficiencies, the latter of which develop because of a specific illness or condition or are treatment-related. The effects of treatment for neoplasia, autoimmune diseases, solid organ and stem cell transplants on host defenses are reviewed and associated with susceptibility to particular infections. In conclusion, an approach to laboratory screening for a suspected immunodeficiency is presented. Knowledge of which host defects predispose to specific infections allows clinicians to prevent, diagnose, and manage infections in their immunocompromised patients most effectively.

Candida albicans HWP1 gene expression and host antibody responses in colonization and disease

In vivo expression of the developmentally regulated Candida albicans hyphal wall protein 1 (HWP1) gene was analysed in human subjects who were culture positive for C. albicans and had oral symptoms (n=40) or were asymptomatic (n=29), or had vaginal symptoms (n=40) or were asymptomatic (n=29). HWP1 mRNA was present regardless of symptoms, implicating hyphal and possibly pseudohyphal forms in mucosal carriage as well as disease. As expected, in control subjects without oral symptoms (n=10) and without vaginal symptoms (n=10) who were culture negative in oral and vaginal samples, HWP1 mRNA was not detected. However, exposure to Hwp1 in healthy culture-negative controls, as well as in oral candidiasis and asymptomatic mucosal infections, was shown by the existence of local salivary and systemic adaptive antibody responses to Hwp1. The results are consistent with a role for Hwp1 in gastrointestinal colonization as well as in mucosal symptomatic and asymptomatic infections. Overall, Hwp1 and hyphal growth forms appear to be important factors in benign and invasive interactions of C. albicans with human hosts.

Dysregulation of Expression of Immunoregulatory and Cytokine Genes and Its Association with the Immaturity in Neonatal Phagocytic and Cellular Immunity

BACKGROUND

Innate and adaptive immunity is comprised of cellular and humoral factors that provide rapid protection against microbial invasion. However, immaturity of innate and adaptive immune responses in the perinatal period predisposes the neonate to increased infectious morbidity and mortality from a variety of organisms.

OBJECTIVES

To elucidate dysregulation of expression of various immunoregulatory and cytokine genes and its association with the immaturity in neonatal phagocytic cellular immunity.

METHODS

Comparison of protein production and mRNA of granulocyte macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-12, IL-15 and IL-18 in adult peripheral blood (APB) mononuclear cells (MNC) and cord blood (CB) MNC was studied. Effects of hematopoietic growth factors (HGFs, GM-CSF, M-CSF, G-CSF, IL-11) were studied in vivo in rats as well as randomized controlled studies conducted in neonates. Oligonucleotide microarrays were used to study gene expression patterns of activated CB and APB monocytes and dendritic cells.

RESULTS AND CONCLUSIONS

We demonstrated dysregulation of various immunoregulatory and cytokine genes in CB MNC. This dysregulation may in part explain the immaturity of neonatal cell-mediated immunity. There are probably various dysregulated cytokines yet to be discovered. Biological agents such as IL-2, IL-12, IL-11 and/or IL-18 alone or in combination with HGFs should be considered for future studies to identify new approaches to enhance neonatal host defense, and thereby decrease the incidence of neonatal sepsis and the consequent high risk of morbidity and mortality.

Pediatric case series evaluating a standardized Candida albicans skin test product

BACKGROUND

A ready-to-use, standardized Candida albicans skin test product (Candin) first became available in 1995. As of April 6, 2004, no published reports have been found describing efficacy or safety with pediatric use of this reagent.

OBJECTIVE

To present a case series describing experience with use of Candin to assess 78 pediatric cases for delayed-type hypersensitivity.

METHODS

The standardized C. albicans reagent was one of up to 4 antigens used to evaluate patients' cellular immunity. Candin was used with purified protein derivative tuberculosis testing for 76 patients (4 mo-16 y of age) and for anergy testing alone in 2 cases. Candin was used with at least one other skin test reagent for 24 subjects.

RESULTS

Fifty-three of 78 subjects (68%) responded to at least one skin test antigen. Candin had an overall response rate of 64% (50/78). There was a response to Candin in 54% (13/24) of subjects with multiple reagents applied, the highest rate of any antigen used. There was a 27% (3/11) positive Candin response for subjects <1 year of age; this compared with 21% and 23% in 2 published reports on use of nonstandardized tests for this age group. No adverse events were associated with use of Candin.

CONCLUSIONS

Candin testing gives similar or better response rates compared with published data on older, nonstandardized C. albicans reagents and other anergy test antigens used in this case series. It should be used in combination with multiple other control antigens to most effectively assess for anergy, particularly in infants, as well as in patients recognized to be immune deficient.

Experimental Candida albicans lesions in healthy humans: dependence on skin pH

The addition of suspensions of Candida albicans cells under occlusion to the left and right forearms, buffered at 2 different pH levels (6.0 and 4.5), resulted after 24 h in unilateral or bilateral lesions in 14 of 15 volunteers. The resulting skin-surface pH was 5.7+/-0.3 and 5.1+/-0.2, respectively. The lesions were more pronounced on the arm with the higher pH in all 14 subjects who reacted. In 11 cases, reactions occurred only on the arm with the higher pH. The pH-induced results are not due to inhibited growth of C. albicans. They may be due to a pH dependence of the yeast's virulence capacity and/or a modulation of the host's defence ability. The use of skin-occlusive products (e.g. dressings, diapers and panty liners) is known to raise skin pH and is associated with skin infections of C. albicans. An acidic buffer incorporated in such products could be a preventive measure for Candida-induced skin rash.

Screening for delayed-hypersensitivity in Italian children: multicentric study by multitest skin testing

The Multitest skin test allows the simultaneous intradermal application of seven standardized recall antigens in a reproducible manner. Response reading is based on a scoring system that distinguishes between normal and diminished delayed hypersensitivity (DH). To determine incidence and size of DH responses for each antigen in relation to age and sex in healthy Italian children, a multicentric study was performed on a representative paediatric population of 491 subjects (285 males and 296 females) aged from 4 months to 16 years. In both sexes DH reactivity as measured by score and number of positive responses increased significantly with age. The incidence of anergy was 8.8% for the whole population and decreased significantly with age in both sexes. Incidence of positive responses was highest for tetanus and diphteria toxoids, intermediate for Candida, Proteus and Streptococcus, and lowest for tuberculin and Trichophyton antigens. There was no significant difference between sexes in the incidence of positive response to each antigen.

Contact sensitivity to Candida albicans--comparative studies in man and animal (guinea-pig)

We studied the elicitation of contact sensitivity to Candida albicans antigen in guinea-pigs with experimental cutaneous candidiasis and in humans, using commercially available potent 1:100 C. albicans antigen (Torii) by patch testing on abraded skin. In guinea-pigs, non-immune animals became patch test-reactive 4-5 days after topical application of viable C. albicans, either under occlusion or without occlusive dressings, concurrently with the demonstrability of delayed responses to intradermally injected 1:10 000 Candida antigen. In humans, all healthy adults who showed delayed hypersensitivity reactions to intradermally injected 1:10 000 C. albicans antigen demonstrated positive patch-test reactions to 1:100 C. albicans antigen. There was a significant correlation between the magnitude of responses to these tests. In contrast, no positive patch test reactions were elicited to the 1:100 C. albicans antigen on neonatal skin, emphasizing the lack of irritability of this test agent. These results also indicate that in humans contact sensitivity to Candida antigen occurs during later life because C. albicans is a ubiquitous organism. The practical value of this Candida patch test for evaluation of patients' immune function was assessed by a prospective study in patients with various skin disorders. The results obtained suggested some potential value of the test for evaluation of cell-mediated immune function of patients with regard to ubiquitous recall antigens.

Delayed cutaneous hypersensitivity in normals: choice of antigens and comparison to in vitro assays of cell-mediated immunity

In 81 normal subjects, ages 19 to 100 yr (mean 52), we studied the prevalence of positive 48 hr skin reactions to six antigens: fluid tetanus toxoid, Candida albicans, SK/SD, Trichophyton, PPD, and coccidioidin. Of these, C. albicans was most frequently reactive (92%); SK/SD (51%) and tetanus (49%) were less so. Each of the remaining three antigens was reactive in less than 42% of the subjects. The minimum number of antigens required to detect delayed hypersensitivity in 100% of subjects was two: C. albicans and tetanus. We found no correlation between skin reactivity at 20 min, 6 hr, and 48 hr for most of the antigens studied, suggesting different mechanisms for reactions occurring at each time. In 60 of the subjects, lymphocyte stimulation index (LSI) with tetanus toxoid and monocyte chemotaxis (MC) assays were done. The natural log of the area of induration at 48 hr after tetanus skin testing (I48) increased as a function of LSI (p less than 0.005) and MC (p less than 0.025) by multiple regression analysis. Skin testing was less sensitive than LSI as a test for cell-mediated immunity in our population. However, because of availability and correlation with LSI, delayed cutaneous hypersensitivity should be tested initially. For this purpose, tetanus toxoid appears to be a useful antigen when used in combination with C. albicans.

In vivo and in vitro cell-mediated immunity to tetanus toxoid in adults

The purpose of this study was to evaluate tetanus toxoid (TT) as an indicator of cutaneous delayed hypersensitivity (CDH) in adults. Fifty-two normal subjects, aged 25 to 64 yr, were skin tested with TT and streptokinase-streptodornase (SK/SD). Lymphocyte transformation was studied in seven normal TT reactors, four normal TT nonreactors, and seven hospitalized anergic patients. CDH was common with both TT and SK/SD; 90% of the adults, aged 25 to 39 yr, had CDH reactions to TT and 79% had CDH reactions to SK/SD. In adults aged 40 to 64 yr, 75% had DCH reactions to TT and 59% had CDH reactions to SK/SD. Lymphocyte transformation to TT correlated well with TT skin-test results. Punch biopsy specimens of TT reactions 48 hr after skin testing demonstrated DCH. We conclude that TT is an excellent antigen for assessing the presence or absence of CDH in adults aged 25 to 64 yr.