Emma Guerra

Changes in circulating B cells and immunoglobulin classes and subclasses in a healthy aged population

The study of 87 adults of different ages, including 15 centenarians, selected for their healthy status, showed that profound changes of humoral immunity occur throughout life. In particuIar, a statistically significant age‐reIated increase of the serum level of immunoglobulin cIasses (IgG and IgA but not IgM) and IgG subcIasses (IgGI, 2 and 3, but not IgG4) was detected. A parallel age‐related decrease of circuIating B cells was also observed. The hypothesis of a complex derangement of B cell function and/or compartmentalization with age is put forward, together with the proposal that healthy centenarians (as representative of successful ageing) may be helpful in identifying the physiological age‐reIated modifications of the immune system.

Proliferative and cytotoxic responses to mannoproteins of Candida albicans by peripheral blood lymphocytes of HIV-infected subjects.

Mucosal candidiasis is one of the first opportunistic diseases in HIV‐infected subjects. In order to understand the relationship between this disease and immunodeficiency to chemically defined, immunodominant Candida antigens, a mannoprotein fraction from C. albicans cell wall (GMP) was used to analyse proliferative and non‐MHC‐restricted cytotoxic responses of peripheral blood mononuclear cells (PBMC) from normal and HIV‐infected subjects. In the former, GMP induced extensive blastogenesis, generation of powerful cytotoxicity against a tumour cell line (K562), and production of substantial amounts of interferon‐gamma (IFN‐γ). Cultured PBMC from HIV‐infected subjects manifested an early decreased ability for proliferative as well as differentia live cytotoxic responses to the candidal mannoproteins. This inability became clearly evident in subjects with stage III (CDC) of the disease, was total in CDC stage IV and occurred even in some subjects with a normal number of CD4+ cells. Low or absent response to GMP correlated with lack of response to tetanus toxoid. In contrast, both lymphoproliferative and cytotoxic responses to exogeneous IL‐2 was highly preserved at all stages of infection. The production of IFN‐γ in GMP‐stimulated PBMC cultures critically fell to negligible values in most of the subjects in CDC stages II and III. Thus, the lowered or absent cell‐mediated immune responses to candidal mannoprotein may be one factor to explain the early, elevated susceptibility of HIV‐infected subjects to mucosal candidiasis. This study also shows that our mannoprotein preparation may be used as a probe to detect the overall efficiency of T cell responses in the above subjects.

Phase II controlled trial of post-exposure immunization with recombinant gp160 versus antiretroviral therapy in asymptomatic HIV-1-infected adults

Objective:To alter the natural course of HIV-1 infection by inducing or potentiating immune responses to HIV-1 envelope glycoprotein. Design:Multicentre, double-blind, three-arm, placebo-controlled study. Setting:Outpatients attending clinics in two University Hospitals. Patients:Ninety-nine asymptomatic HIV-1-infected adults with CD4+ T-cell counts > 400 and < 600 × 106/l and no previous antiretroviral therapy were included. Interventions:Patients were randomly assigned to three groups treated with: (i) gp160 in alum over a 2-year period in combination with placebo for the full study duration (n = 32); (ii) gp160 in alum over a 2-year period in combination with zidovudine for the full study duration (n = 34); and (iii) alum over a 2-year period in combination with zidovudine for the full study duration (n = 33). Results:Immunotherapy was well tolerated and no significant differences in disease progression were seen in the treatment groups. The majority of patients (85%) receiving gp160 showed persistent lymphoproliferative responses to the immunogen and to a different Env antigen preparation. CD4+ cell count changes in patients receiving zidovudine alone were significantly higher than those seen in patients receiving immunotherapy alone after 1 year of treatment. Zidovudine administration was associated with initial transient reduction of plasma viraemia. Conclusions:Prolonged immunization with a soluble HIV-1 subunit provided no benefit to asymptomatic HIV-1-infected patients and was inferior to zidovudine monotherapy. Furthermore, immunization with gp160 shortened the duration of the transient viral load reduction induced by zidovudine.

Lipid transfer protein sensitization: reactivity profiles and clinical risk assessment in an Italian cohort

Nonspecific lipid transfer proteins (nsLTPs) represent a major cause of systemic food allergic reactions in the Mediterranean area. This study investigate hierarchical patterns and cluster relationships of IgE sensitization to different nsLTPs, and the relationship to clinical allergy in a large Italian cohort.

HIV-specific lymphoproliferative responses in asymptomatic HIV-infected individuals

In vitro lymphoproliferative responses to HIV‐1 recombinant antigens (gp160, p24, and Rev protein) were studied in 83 patients with asymptomatic HIV‐1 infection (CDC groups 11 and III) and circulating CD4 lymphocyte numbers > 400/mm3. Significant response to at least one of the three antigens was detected in 52.4% of the subjects, but the responses were weak, and concordance of the response to the three antigens was rare, the frequency of individuals responding to each antigen not exceeding 22.4%. Increasing frequencies of response were observed when recall antigens (tetanus toxoid and Candida albicans glycomannoprotein) (65.5%) and anti‐CD3 MoAb (76.6%) were used as stimuli. Although a significant association between lymphocyte response to p24, but not gp160, and steadiness of CD4 lymphocyte numbers before the assay was observed, no predictive value for lack of CD4 cell decrease was confirmed for either antigen, and fluctuation of the responses to HIV antigens was seen during subsequent follow up. The panel of T cell assays used could be regarded as appropriate for monitoring both HIV‐specific responses and T lymphocyte function during immunotherapy with soluble HIV antigens.

Urticaria and adult celiac disease

had had seasonal rhinoconjunctivitis and asthma for the last 10 years. Ten minutes after eating a BN, she developed pharyngeal itching, lip swelling, dysphonia, dyspnea, wheezing, and generalized macular exanthema. She was treated with epinephrine, intravenous corticosteroids, and antihistamines v.o. The symptoms resolved within 4±5 h. She had previously developed oral allergy syndrome after eating almond (A), walnut (W), sun ̄ower seed (S), and hazelnut (H). She had suffered from abdominal pain after eating chestnut (CH). She tolerated peanut (P) and pistachio (PI). Prick tests (PT) with common inhalants were positive for pollen from Olea, Poaceae, Artemisia, and Plantago. Prick-by-prick (PBP) with BN and PT with a 1:10 w/v BN extract were positive. PT and PBP with A, P, CH, SS, and PI were positive. PBP with H, W, and cashew nut were positive. A wheal 5 mm greater than saline control was considered positive. Twenty-®ve atopic and nonatopic control subjects were negative. Speci®c IgE (UniCAP, Pharmacia) was determined with the following results: A, P, CH, and PI, class 2; H and S, class 3; IgE for BN, class 2 (2.37 kU/l). SDS±PAGE (12.5%) was carried out by the method of Laemmli. For analysis of the BN proteins within the low-molecular-weight range, a tricineSDS±PAGE system was prepared. In both tests, the samples were under reducing conditions (RC) ± with b-mercaptoethanol ± and no reducing conditions (NRC) ± without this agent, which causes rupture of the interchain disul®de links. SDS±PAGE under NRC revealed six bands of 48.7 (21%), 40 (15.3%), 37.7 (2.6%), and 10.2 kDa (43.8%). Under RC, SDS±PAGE showed 10 bands from 33.7 to 10.3 kDa. In the tricine SDS±PAGE, under NRC, appeared nine bands of 30.1 (22.7%), 28.2 (15.9%), 25.9 (4.8%), 25.2 (2.3%), 20 (2.7%), 17.8 (3%), 8.8 (8.3%), 7.7 (34%), and 5.6 kDa (5.7%). The tricine SDS±PAGE under RC showed nine bands from 25 to 5 kDa. The SDS±PAGE immunoblotting assay under NRC revealed IgE binding to ®ve bands of 52.2, 41.4, 39, 33.4, and 23.7 kDa. IgE binding under RC was restricted to two bands of 33.4 and 21.4 kDa. The tricine SDS±PAGE immunoblotting, under NRC, revealed IgE binding to bands of 19.3, 18.4, and a wide band of 7.22 kDa, probably the 2S albumin. A loss of binding was observed under RC. This fact revealed the importance of the tertiary structure of proteins in the IgE recognition of epitopes. The increased consumption of tropical nuts, especially in the UK and the USA, in recent years has increased IgE-mediated hypersensitivity. The ®rst cases of anaphylaxis were reported by Hide (2) in 1983. In 1991, Arshad et al. (3) reported 12 allergic reactions, seven of which were anaphylaxis. In 1996, Ewan (4) investigated the clinical features of acute allergic reactions to peanuts and other nuts in 62 patients; 42% of them were multisensitized to nuts. BN was the second sensitizing nut after peanut. Also in 1996, Nordlee et al. (6) (as in a previous study [5]) demonstrated that 2S albumin is the major allergen of BN (Ber e I). Moreover, they showed that transgenic soybean, enriched with 2S albumin of BN, can bind IgE from subjects allergic to BN. In 1997, Bartolome et al. (7) reported the ®rst case of anaphylaxis in Spain caused by oral contact with a BN. BN consumption in Spain is still very low compared with the USA and the UK. Here we report the second known case of anaphylaxis in Spain.

Increased IL-6 gene expression and production in patients with common variable immunodeficiency.

We have studied IL‐6 gene expression and production by in vitro stimulated peripheral blood mononuclear cells (PBMC) isolated from common variable immunodeficiency (CVI) patients. A strong hybridization signal for the IL‐6 probe was observed in mRNA extracted from phyto‐haemagglutinin (PHA)‐ and PH A/phorbol myristate acetate (PMA)‐stimulated PBMC from most of 12 CVI patients analysed. IL‐6 production by PHA‐stimulated PBMC from 28 CVI patients was evaluated in ELISA and found to be significantly (P < 0.0001) higher than in normal controls. IL‐6 production, however, did not correlate with the lymphocyte populations examined, nor with the absolute number of monocytes. We have also showed that IL‐6 was able to increase IgM secretion by several Epstein Barr virus (EBV)‐transformcd cell lines derived from both normal donors and CVI patients, but it failed to modify substantially the amounts of IgM and IgG produced in vitro by PBMC derived from CVI patients and activated with pokeweed mitogen (PWM) or anti‐IgM. Our data indicate that IL‐6 gene expression and production is increased in CVI, but CVI cells do not respond to IL‐6 with increased production of immunoglobulin.

Silent HIV infection

The period of latency between infection by the human immunodeficiency virus type-1 (HIV-1) and the production of specific antibodies to viral antigens may be prolonged and, occasionally, may last for years. This condition of seronegative infection could represent a serious risk of viral transmission from subjects who are unaware of their status. However, whether these individuals are actually infectious, especially through body fluids, has not been clarified. We have performed a prospective study in 65 high-risk individuals seronegative for HIV-1 antibodies for a prolonged period of time. Twelve of them (18%) were shown to be carriers of HIV-1 proviral sequences by the polymerase chain reaction (PCR). The virus was isolated from mitogen-stimulated peripheral blood lymphocytes in five out of ten subjects tested since the first positive PCR. In two of them, virus could also be isolated from cell-free plasma, subsequently they remained seronegative during 10 months of follow-up. These data indicate that delayed seroconversions may be associated with productive infection, suggesting that mechanism(s) other than viral latency may be responsible for the absence of antibody responses to HIV-1 proteins. Furthermore, our findings suggest that prolonged seronegative individuals can transmit HIV infection through their body fluids.

Spontaneous allergy to ampicillin and local anesthetics

tests, RIST, RAST, CAST-ELISA, IgG, CIC, ECP and tryptase, CD4, CD8, CD23, and CD28. A decrease in specific IgE (total IgE was unaltered), CD4, CD23, and CD28 and an increase in IgG (IgG1, IgG4) and CD8 were recorded as early as at 6 months of therapy. During the course of treatment, there was a diminution of IgE in favor of IgG, and a reduction in eosinophil count induced by specific provocation. These effects may be related to a decrease in the production of IL-4 and IL-5, as shown in some recent studies (4). Allergen SIT requires high motivation and collaboration from the patient. In our study, as shown in Table 1, the best results by SIT were achieved in patients with the diagnosis of allergic rhinitis treated with grass-pollen allergen mixture. The number of patients who were subjected to SIT (in the analyzed period) was significantly increased, due to the introduction of various allergens such as ragweed, tree-pollen mixture, birch, and house-dust mite. In a limited number of patients who suffered from allergic rhinitis, atopic bronchitis, and atopic dermatitis, SIT was also successfully applied. During the SIT, no case of anaphylactic reaction was recorded. In conclusion, a better understanding of the mechanisms of allergic reactions will offer new ways of treatment based on the use of antigenic peptides, cytokines, and cytokine inhibitors, with remarkable reduction of side-effects (5, 6).

CD28 costimulation and T lymphocyte proliferative responses in HIV-1 infection

To investigate whether defective costimulatory signals could be involved in the loss of T lymphocyte functions during HIV‐1 infection, we tested the effect of CD28 costimulation on both T cell receptor/CD3 and HIV‐1 antigen‐induced proliferative responses. Although CD3‐mediated responses significantly decreased with more advanced stages of HIV‐1 infection, the ability of potentiating the responses through CD28 costimulation was maintained at all stages and did not differ from that of HIV‐1− subjects. When CD28 costimulation was studied in lymphocyte cultures stimulated with HIV‐1 gp160 or p24, potentiation was seen only when a significant response was present without additional CD28 triggering, namely in subjects receiving active immunization with recombinant gp160. These results confirm the integrity of the CD28 pathway of costimulation during HIV‐1 infection, and suggest that lymphocytes responding to soluble HIV‐1 antigen are not deleted in HIV‐1‐infected patients, but do not receive significant priming during the natural course of the infection.