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C Mayorga

Publications and source records attributed to C Mayorga.

At least 55 records · Page 3Linked to original sources
PubMed1997

The presence of latex can induce false-positive skin tests in subjects tested with penicillin determinants.

Latex allergens are ubiquitous, and exposure may occur from different sources in the medical environment and in daily life. The observation that subjects with latex allergy were skin test positive to major and minor determinants of penicillins led our group to carry out an investigation to try to explain these findings. A group of 20 subjects with a history of allergy to latex and with positive skin tests for, but good tolerance of, penicillins was studied. The presence of latex contaminants was studied by RAST and RAST inhibition. Sixteen of the subjects were positive to at least one of the penicillin determinants used, and 14 (87%) of these were positive to at least two determinants. Repetition of skin tests using the container without a stopper changed the skin test results to negative in almost all cases, indicating that some trace contaminants had still been present. RAST-inhibition studies showed that in all penicillin determinants there were trace amounts of latex allergens varying between 3 and 0.03 micrograms/ml. These results indicate that skin tests with penicillin in subjects allergic to latex may give false-positive results and lead to such patients being falsely diagnosed as allergic to betalactams when penicillins are stored in containers with rubber stoppers.

Adolescent↗
PubMed1997

Immediate hypersensitivity to penicillins. Studies on Italian subjects.

The IgE response, the involvement of the different penicillins available for therapeutic use, and the specificity of the IgE antibodies found in a group of penicillin-allergic subjects from Italy were studied. Thirty subjects with a history of allergic reactions to penicillins were studied. In vivo and in vitro specific IgE antibodies were determined to different penicillin determinants. Fifteen subjects developed anaphylactic responses and the remainder urticaria and angioedema. The drug most frequently involved in the patients' allergic reactions was ampicillin (AMP). The benzylpenicilloyl (BPO) skin test was positive in 16 (53.3%) patients, whereas 23 (76.6%) patients were positive to minor determinant mixture (MDM), benzylpenicillin (PG), AMP, or amoxicillin (AX). When classified according to initial reaction type, most anaphylactic patients (93.3%) were associated with minor determinant reactivity, whereas most urticaria patients (80%) reacted to BPO. RAST results for the anaphylactic and urticaria subgroups were similar. RAST inhibition showed that most sera contained highly cross-reactive IgE antibodies. There was evidence of a specific response to AX and PG (one patient each). These data show that in a population of penicillin-allergic patients from Italy, AMP was the main drug inducing the allergic reaction. In skin tests and RAST, patients exhibited heterogeneous IgE responses with little indication of specific reactivity to AMP.

Adolescent↗
PubMed1997

Allergic reactions to ampicillin. Studies on the specificity and selectivity in subjects with immediate reactions.

BACKGROUND: Ampicillin (AMP) is a drug that has been prescribed extensively. Reactions that have been reported include exanthema, desquamative contact eczema, urticaria and anaphylaxis. Experimental evidence indicates that the side chain of AMP is a structure that may induce a selective immune response either at the humoral or lymphocyte T-cell level. With regard to IgE reactions, the selectivity and specificity of the response needs to be studied in humans. OBJECTIVES: To study the specificity of the IgE response in a group of subjects who had an immediate allergic reaction after the administration of AMP. METHODS: Subjects developing an immediate response (anaphylaxis or urticaria) after the administration of AMP or an aminopenicillin derivative with the same side chain as AMP were studied. Skin tests were made to determinants generated from benzyl penicillin (BP): benzyl penicilloyl (BPO) and minor determinant mixture (MDM), as well as amoxicillin (AX) and AMP. Specific IgE antibodies were determined to benzyl penicilloyl polylisine (BPO-PLL), amoxicilloyl-polylisine (AX-PLL) and ampicilloyl-polylisine (AMP-PLL). The specificity of the IgE antibody response was studied by RAST and RAST inhibition. Subjects were classified in three categories: group A: those who were skin test and/or RAST positive to determinants derived from benzylpenicillin, group B: those who were negative to determinants derived from benzylpenicillin but were skin test and/or RAST positive to determinants derived from AX and AMP and group C: those who were exclusively positive to determinants derived from AMP. RESULTS: A total of 48 subjects was included in the study. In group A there were 35 cases, in group B 10 cases, and in group C three cases. RAST inhibition studies showed that in some instances the side chain of AMP could induce specific responses with a variable degree of crossreactivity between BP and AX. CONCLUSIONS: Although AMP can induce an immediate IgE response in subjects allergic to betalactams and the structure of the side chain may contribute to the specificity of the response, our results indicate that in most instances crossreactivity with the other penicillins exists and that in the groups studied selective reactions to just AMP derived determinants were uncommon.

Adult↗
PubMed1996

Anaphylaxis to penicillins after non-therapeutic exposure: an immunological investigation.

BACKGROUND: There are instances where individuals may come into contact with penicillins without being aware of it. This non-therapeutic exposure from different sources may cause sensitization and even clinical manifestations in subjects allergic to penicillins. OBJECTIVE: To determine the capacity that inadvertent contact with penicillins may have in inducing resensitization and symptoms in patients diagnosed as allergic to penicillins who were followed over a long period of time after their initial evaluation. METHODS: A follow-up study of penicillin-allergic subjects who agreed to be regularly tested for in vitro and in vivo control of their sensitivity. Skin tests were carried out with major and minor determinants of benzylpenicillin (BPO and MDM), amoxicillin (AX), and ampicillin (AMP), and specific IgE antibodies were determined by radioallergosorbent test (RAST). A questionnaire was sent to and answered by the subjects in order to see if they experienced symptoms at any time during the follow-up period. In addition, if any unexplained symptoms occurred, a bleeper system was used to contact the allergy centre. RESULTS: Seven subjects experienced anaphylactic reactions with no obvious cause. At the time of their initial allergic reaction, which was caused by exposure to prescribed penicillin, the subjects had one or more positive skin tests and/or RAST results to penicillin related reagents. However, over the following 2-4 years all their tests became negative. After reporting their unexplained reaction all seven had one or more positive skin tests and/or RAST results again and when retested 1 week later RAST measurements showed that levels of penicillin-specific IgE were maintained or increased. None of the subjects had knowingly received penicillin but the questionnaire showed that six had been exposed to it and in the seventh case exposure was likely. In two cases contact was by sexual intercourse with a partner who was receiving penicillin, three subjects had handled penicillin formulations and one had drunk from a glass previously used for giving penicillin. In the seventh case exposure could have occurred whilst in hospital for surgery, although this was not proven. CONCLUSIONS: these results show that non-therapeutic exposure to penicillin can cause severe symptoms and that in vitro and in vivo testing can help in the diagnosis of such cases.

Adult↗
PubMed1995

Epitope mapping of beta-lactam antibiotics with the use of monoclonal antibodies.

In order to evaluate the antigenic contribution of different regions of the penicillin molecule, monoclonal antibodies were raised against amoxicillin-protein conjugates and their specificities analysed in detail. A random sample of the clones produced was analysed by a quantitative inhibition-ELISA, using, as inhibitors, monomeric conjugates of the following antibiotics to butylamine (BA), amoxicillin (AX), ampicillin (AMP), benzylpenicillin (BP) and the nuclear part of these, 6-aminopenicillanic acid (6-APA); and different parts of the following molecules: N-(p-hydroxyphenyl)-glycine (PHPG), N-phenylglycine (NPG), phenylacetic acid (PA) and thiazolidine (TIAZ). The results showed that 92% of the antibodies recognized an epitope in which the side chain was a major constituent, although with variable contributions from other regions of the molecule. There was a high degree of crossreactivity with aminopenicillins, but low or absent crossreactivity with BP. None of the antibodies recognized the thiazolidine ring or the conjugated nuclear region of the penicillins. Finally, one antibody seemed to recognize, equally, all the different structures tested. The possible relevance of these results to penicillin allergy is discussed.

Amoxicillin↗
PubMed1995

Studies of the specificities of IgE antibodies found in sera from subjects with allergic reactions to penicillins.

Penicillins are immunogenic when administered to humans and in some instances they can also be allergenic, inducing specific IgE antibodies. Whilst the major haptenic group, the penicilloyl, is well characterised, less is known about the relative importance of the different parts of the structure for antibody binding and how this can influence the specificity of patients response. In order to investigate this further, sera from subjects who had suffered an IgE-mediated reaction to penicillins were studied using the radioallergosorbent test (RAST) and RAST inhibition. The assays employed reagents related to the penicillins causing the reaction. Using 173 sera, positive RAST results were only found with reagents based on benzyl penicillin (BP) and amoxicillin (AX). Fifty-three positive sera were selected for further studies and categorized into three groups: (A) sera only RAST positive to AX, (B) sera only positive to BP and (C) sera positive to both penicillins. RAST inhibition studies were then carried out using monomeric penicilloyl conjugates and compounds representing parts of the penicilloyl structures of BP and AX. For all three groups, monomeric penicilloyl conjugates were the most efficient inhibitors but there were differences for the other compounds. Group A sera were also inhibited by the side chain amoxicillin, whereas group B sera were poorly inhibited by all other inhibitors. Group C sera showed two patterns of inhibition, both consistent with their more cross-reactive profile.

Amoxicillin↗
PubMed1992

Determination of IgE antibodies to the benzyl penicilloyl determinant. A comparison between poly-L-lysine and human serum albumin as carriers.

The influence of two different carriers, poly-L-lysine (PLL) and human serum albumin (HSA) in the binding of specific IgE antibodies to the benzyl penicilloyl hapten (BPO) was determined in a solid-phase assay. Serum samples from patients with a history of immediate reaction to penicillin and which had shown the presence of IgE antibodies to BPO were used. Benzyl penicilloyl derivatized cellulose discs were prepared using PLL of different molecular weight and HSA as carriers. These were treated with different molar ratios of benzyl penicillin. These reagents were compared for uptake of BPO-specific IgE using a pool of sera in a radioallergosorbent test (RAST) type assay. Two PLL systems and two HSA systems were finally compared using 26 individual sera. RAST values were compared by Kruskal-Wallis and Wilcoxon tests. The relationships between the four different assays were evaluated by determining Pearson correlation coefficients and the concordance by determining intraclass correlation coefficients (ICC). Analysis of means by the Wilcoxon test revealed significant differences (P less than 0.01) only when the different carrier assays were compared. The correlation coefficients between all the assays were significant (P less than 0.0001), but the ICC was low when the different carrier assays were compared. These results indicate that the nature of the carriers studied (PLL and HSA) influences the capacity for binding IgE antibodies in the RAST procedure. The differences observed indicate that one conjugate cannot be substituted for the other in the determination of IgE antibodies to BPO and that BPO-PLL is preferable.

Antibodies↗
PubMed1991

Differences in serum IgE antibody activity to benzylpenicillin and amoxicillin measured by RAST in a group of penicillin allergic patients.

To determine the influence of the acyl side chain on the IgE antibody specificity of the two most common penicillins inducing allergic reactions in our community, benzylpenicillin (BP) and amoxicillin (AX), IgE positive sera from a group of 24 patients allergic to penicillin were studied. RAST was determined in parallel to benzyl penicilloyl-polylysine (BPO-PLL) and amoxicilloyl-polylysine (AX-PLL) in each serum, and values greater than an established coefficient of variation of 15% were considered as different for either of the haptens used (BP and AX). 16 sera proved to be more positive to BP (Group A), six to AX (Group B) and in two IgE was positive to both haptens with a similar value (Group C). RAST titration concentration effect curves and RAST inhibition studies with a pool of sera from each group (A, B, C) and individual sera showed that most of them were more specific for either BPO or AX, a minority being of similar value to both. These findings indicate that the side chain structure of penicillins is relevant in the constitution of the antigenic determinant, although in some instances the common chemical structure of betalactam is recognised mainly by the IgE antibodies. The clinical relevance of these data needs to be established.

Amoxicillin↗
PubMedDate not supplied

Different lymphocyte markers and cytokine expression in peripheral blood mononuclear cells in children with acute atopic dermatitis.

BACKGROUND: The pathogenesis of atopic dermatitis (AD) is still not completely understood. AD is characterized by the presence of clinical symptoms of both IgE antibody-mediated immediate hypersensitivity and specific T lymphocyte-mediated delayed hypersensitivity. OBJECTIVE: To evaluate the immunological mechanisms involved in children with acute AD lesions. MATERIAL AND METHODS: Ten children with acute AD lesions and 10 non-atopic controls were studied. Total IgE was measured by immunoassay. T cell marker expression (CD3, CD4, CD8, cutaneous lymphocyte-associated antigen [CLA]) and cytokine production (interferon [IFN]-gamma, interleukin [IL]-13) were analyzed in peripheral blood mononuclear cells by flow cytometry. RESULTS: In children with AD the percentage of CD3+ cells (p = 0.015) increased while that of CD8+ cells (p = 0.023) decreased, with no differences in CLA expression. We found increased IL-13 production in CD3+ cells (p = 0.01) and CD3+CD4+ (p = 0.001) cells with no difference in IFN-gamma. Total IgE was significantly higher in patients with AD (p = 0.01). Comparison of IL-13 production in CD4+ cells categorized by total IgE level showed that IL-13 production was significantly increased in subjects with a higher IgE level. CONCLUSION: Peripheral blood from children with AD showed an increase in IgE levels and a Th2 pattern. There was a correlation between IL-13 production and total IgE levels.

Antigens, CD↗
PubMedDate not supplied

Differences in the immunological responses in drug- and virus-induced cutaneous reactions in children.

The cutaneous symptoms in non-immediate reactions to drugs are not always clinically distinguishable from those induced by viruses, especially during the early phase of the reaction. Moreover, viral infections and drug reactions often coexist and identification of the etiological agent is necessary. Discerning the differences in the immunological response between both may help in the diagnosis. The aim of this study was to determine possible differences in the immunological response in non-immediate cutaneous reactions to drugs versus cutaneous viral-induced diseases in children. Two groups of children were evaluated: one with non-immediate drug-induced cutaneous reactions (DICR) and another with virus-induced cutaneous reactions (VICR). A third group of children taking the same drugs as the DICR group and with no cutaneous disease or viral infections was included as controls. The lymphocyte markers CD3, CD4, CD8, CD16, CD19, CLA, CD25, CD69, CD45RO, CD45RA were determined by flow cytometry. IL-2, IL-4, IL-5, IFN-gamma, TNF-alpha and IL-10 mRNA were measured by RT-PCR. Data were compared by non-parametric and chi(2) statistical analysis. In DICR group (n=8) the diagnosis was established by temporal association, improvement after drug withdrawal, patch testing, and in some cases by controlled administration. All patients in the VICR group (n=10) were diagnosed based on a positive viral serology: the presence of IgM antibodies or seroconversion of IgG antibodies. There were significant differences between the three groups in peripheral lymphocytes expressing the skin homing receptor CLA (P < 0.01), the early activation marker CD69 (P < 0.001), and the memory (CD3+CD45RO+) (P < 0.02) and naive (CD3+CD45RA+) (P < 0.03) T cell subsets. Children with DICR showed a TH1 mRNA cytokine pattern whereas those with VICR showed a TH0 pattern. In lymphocyte subpopulations from children, differences in the immunological response between DICR and VICR can be detected in the expressions of the activation marker CD69 and the cutaneous homing receptor CLA, and in cytokine mRNA profiles.

Adolescent↗
PubMedDate not supplied

Memory to the hapten in non-immediate cutaneous allergic reactions to betalactams resides in a lymphocyte subpopulation expressing both CD45RO and CLA markers.

The cutaneous lymphocyte-associated antigen (CLA) is a homing receptor expressed in a subpopulation of memory T lymphocytes that migrates to the skin and participates in different inflammatory processes. The aim of the study was to compare the T cell response to betalactams in both CLA+ and CLA- memory T cell subsets from subjects with non-immediate allergic reactions to these drugs. Three patients with a non-immediate reaction to penicillins were studied during their acute episodes. Peripheral blood mononuclear cells were isolated by Ficoll density gradient and were used for flow cytometry and lymphocyte transformation test assays. CD3+ cells were purified via high affinity negative selection columns. CD45RA+ and CD45RO+ subpopulations were obtained by magnetic sorting and the memory subpopulation was subdivided into CLA+ and CLA- fractions. These were cultured in triplicate together with feeder cells and different concentrations of amoxicillin and benzylpenicillin. In all cases, the proliferative responses to the drugs were confined to the CD45RO+CLA+ subpopulation. The CD45RO+CLA- subset showed no proliferative response to either drug at any concentration. We have shown that the in vitro memory to penicillins in non-immediate cutaneous allergic reactions to these drugs resides in the CD45RO+CD3+ subset expressing CLA, which enables these T cells to migrate to the skin. These findings may have relevance to understanding the involvement of T cells in allergic reactions to penicillins.

Aged↗
PubMedDate not supplied

Toward an in vitro test for the diagnosis of allergy to penicillins. Synthesis, characterization, and use of beta-lactam and beta-lactam metabolite poly-L-lysines which recognize human IgE antibodies.

Conjugates of poly-L-lysine (PLL) containing a penicillin or a penicilloyl residue were prepared and characterized by 1H NMR and by size-exclusion (SE) HPLC. These conjugates were used in a radio allergo sorbent tests (RAST) test for the determination of allergy toward beta-lactams. The chemiometric evaluation of the data indicates that allergy to amoxycillin is different from allergy to the other beta-lactams tested. Furthermore, careful chemical characterization of the conjugates appears to be crucial to obtain meaningful information from the RAST data.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

IgG and IgE antibodies in subjects allergic to penicillins recognize different parts of the penicillin molecule.

BACKGROUND: IgE and IgG antibodies to penicillins can have different specificities. However, this response, including the recognition of the different parts of penicillin, has never been studied in the same subject. OBJECTIVE: Study of the specificity of IgE and IgG antibodies and the relevant parts of the penicillin molecule that contribute to the hapten binding site in sera from human. METHODS: Specific IgE antibodies were determined by RAST and specific IgG antibodies by ELISA. The recognition of the different molecules was studied by inhibition studies. RESULTS: Seven sera with IgG and IgE antibodies to amoxicillin and benzyl penicillin were analyzed. IgE antibodies recognized mainly two different epitopes: in one, the side chain was a relevant part of the epitope, in the other, it was the nuclear portion. IgG antibodies recognized the nuclear portion in all instances. In the same subject, antibodies of different isotype and specificity were found. CONCLUSIONS: Subjects who develop simultaneously IgE and IgG antibodies to penicillins show different specificities. This proves that different populations of antibodies recognize different epitopes.

Antibody Specificity↗
PubMedDate not supplied

Determination of inflammatory markers in allergic reactions to drugs.

Serum tryptase (Tryp) and eosinophil cationic protein (ECP) and urine N-methylhistamine (N-MH) were quantitated in a group of 13 subjects who had experienced immediate allergic reactions to different drugs. Results indicated that both Tryp and N-MH were involved and the levels were related to the severity of the reaction. Results of serum ECP levels failed to provide relevant information concerning the participation of eosinophils in immediate reactions to drugs.

Adolescent↗
PubMedDate not supplied

T cell assessment in allergic drug reactions during the acute phase according to the time of occurrence.

Allergic drug reactions can be classified as immediate, accelerated or delayed. This classification usually correlates with the mechanism involved: immediate reactions are IgE mediated and delayed reactions are T cell dependent. We analyzed lymphocyte involvement in patients with these reactions by determining cell subpopulations, activation state and skin homing receptor expression (CLA) in blood and skin. Patients with immediate, accelerated and delayed reactions were evaluated during the acute phase and after resolution. Controls taking drugs were included. Phenotypic immunofluorescence analysis was done by flow cytometry in peripheral blood, and by immunohistochemistry in skin for delayed reactions. Forty-six patients were included, 17 with immediate reactions, 10 accelerated and 19 delayed. At the acute phase CLA was significantly increased in delayed reactions and HLA-DR in all three types of reaction. In the severest delayed reactions, Steven-Johnson/Lyell syndromes, the CD4 subsets were increased in peripheral blood and skin compared to maculopapular exanthemas and urticaria and HLA-DR when compared with urticaria. In maculopapular exanthemas CLA was significantly increased in peripheral blood and skin compared to urticaria and the severe reactions. We found that T-cells are implicated, besides delayed reactions, in immediate and accelerated reactions. In delayed reactions there is a parallelism between results found in skin and peripheral blood with a higher participation of CD4+ cells the more severe the reaction.

Acute-Phase Reaction↗