Detection of specific IgE antibodies in parasite diseases

Activation of Th1 or Th2 cells is associated with production of specific immunoglobulin isotypes, offering the opportunity to use antibody measurement for evaluation of T cell function. Schistosomiasis and visceral leishmaniasis are diseases associated with Th2 activation. However, an IgE response is not always detected in these patients. In the present study we evaluated specific IgE antibodies to S. mansoni and L. chagasi antigens by ELISA after depletion of serum IgG with protein G immobilized on Sepharose beads or RF-absorbent (purified sheep IgG antibodies anti-human IgG). In schistosomiasis patients, specific IgE to SWAP antigen was demonstrable in only 10 of 21 patients (48%) (mean absorbance ± SD = 0.102 ± 0.195) when unabsorbed serum was used. Depletion of IgG with protein G increased the number of specific IgE-positive tests to 13 (62%) and the use of RF-absorbent increased the number of positive results to 20 (95%) (mean absorbances ± SD = 0.303 ± 0.455 and 0.374 ± 0.477, respectively). Specific IgE anti-L. chagasi antibodies were not detected in unabsorbed serum from visceral leishmaniasis patients. When IgG was depleted with protein G, IgE antibodies were detected in only 3 (11%) of 27 patients, and the use of RF-absorbent permitted the detection of this isotype in all 27 visceral leishmaniasis sera tested (mean absorbance ± SD = 0.104 ± 0.03). These data show that the presence of IgG antibodies may prevent the detection of a specific IgE response in these parasite diseases. RF-absorbent, a reagent that blocks IgG-binding sites and also removes rheumatoid factor, was more efficient than protein G for the demonstration of specific IgE antibodies

T-cell and serological responses to Erp, an exported Mycobacterium tuberculosis protein, in tuberculosis patients and healthy individuals

<p>Abstract</p> <p>Background</p> <p>The identification of antigens able to differentiate tuberculosis (TB) disease from TB infection would be valuable. Cellular and humoral immune responses to Erp (Exported repetitive protein) – a recently identified <it>M. tuberculosis </it>protein – have not yet been investigated in humans and may contribute to this aim.</p> <p>Methods</p> <p>We analyzed the cellular and humoral immune responses to Erp, ESAT-6, Ag85B and PPD in TB patients, in BCG⁺individuals without infection, BCG⁺individuals with latent TB infection (LTBI) and BCG^-controls. We used lymphoproliferation, ELISpot IFN-γ, cytokine production assays and detection of specific human antibodies against recombinant <it>M. tuberculosis </it>proteins.</p> <p>Results</p> <p>We included 22 TB patients, 9 BCG⁺individuals without TB infection, 7 LTBI and 7 BCG^-controls. Erp-specific T cell counts were higher in LTBI than in the other groups. Erp-specific T cell counts were higher in LTBI subjects than TB patients (median positive frequency of 211 SFC/10⁶PBMC (range 118–2000) for LTBI subjects compared to 80 SFC/10⁶PBMC (range 50–191), p = 0.019); responses to PPD and ESAT-6 antigens did not differ between these groups. IFN-γ secretion after Erp stimulation differed between TB patients and LTBI subjects (p = 0.02). Moreover, LTBI subjects but not TB patients or healthy subjects produced IgG3 against Erp.</p> <p>Conclusion</p> <p>The frequencies of IFN-γ-producing specific T cells, the IFN-γ secretion and the production of IgG3 after Erp stimulation are higher in LTBI subjects than in TB patients, whereas PPD and ESAT-6 are not.</p

In vitro morphological studies on antibody-dependent nonimmune lymphocyte-mediated cytotoxicity in chronic active liver disease

Using an in vitro system of antibody-dependent cellular cytotoxicity (ADCC), the killing effect of chronic liver disease sera on target Chang cells, mediated by effector nonimmune lymphocytes (NLy), was studied. NLy destroyed Chang cells in monolayers pretreated with sera of patients with chronic active liver disease (CALD). Sera from these patients with CALD, after receiving steroid therapy, demonstrated a significant decrease of the cytotoxic action of NLy. The target cells treated with sera of normal subjects or patients with chronic persistent hepatitis were only minimally affected. Morphological observations of the cytotoxic action in a CALD serum-treated group showed intimate contact between NLy and the target cells in the areas of the plaques, where large numbers of the target Chang cells were injured and were closely associated with effector NLy. The Chang cells developed cytoplasmic swelling. The surface became ruffled, and intracytoplasmic organelles displayed vesicular degeneration. Thereafter, cell rupture and fragmentation occurred. The sera in patients with CALD appear to possess a membrane reactive factor, presumably antibody, against the surface membrane of Chang cells. This immunological mode of reaction between the effectors and target cells (ADCC) may be important in the perpetuation and pathogenesis of hepatocyte death in CALD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44386/1/10620_2005_Article_BF01073183.pd

Primary sequence contribution to optical function of the eye lens

The crystallins have relatively high refractive increments compared to other proteins. The Greek key motif in βγ-crystallins was compared with that in other proteins, using predictive analysis from a protein database, to see whether this may be related to the refractive increment. Crystallins with Greek keys motifs have significantly higher refractive increments and more salt bridges than other proteins with Greek key domains. Specific amino acid substitutions: lysine and glutamic acid residues are replaced by arginine and aspartic acid, respectively as refractive increment increases. These trends are also seen in S-crystallins suggesting that the primary sequence of crystallins may be specifically enriched with amino acids with appropriate values of refractive increment to meet optical requirements. Comparison of crystallins from five species: two aquatic and three terrestrial shows that the lysine/arginine correlation with refractive increment occurs in all species investigated. This may be linked with formation and maintenance of salt bridges

Allelic polymorphisms in the repeat and promoter regions of the interleukin-4 gene and malaria severity in Ghanaian children

Immunoglobulin E has been associated with severe malaria suggesting a regulatory role for interleukin (IL)-4 and/or IgE in the pathogenesis of severe malaria. We have investigated possible associations between polymorphisms in the IL-4 repeat region (intron 3) and promoter regions (IL-4 +33CT and −590CT) in Ghanaian children with severe malaria. There was a significantly higher frequency of IL-4 intron-3 B1B1 genotype in the cerebral malaria group [P < 0·0001, odds ratio (OR) = 8·7]. The genotype and allele frequencies of the IL-4 –590 and +33 polymorphisms did not differ between the four study groups. Carriers of IL-4 +33T/−590T with cerebral malaria had elevated total IgE compared to non-carriers (P = 0·03). Our data suggest that IL-4 and/or IgE play a regulatory role in the pathogenesis of severe or complicated malaria