et séronégativité ds la BL sur le thread PLS :
http://www.forumlyme.com/phpBB3/viewtop ... 2&start=15
Extrait : http://www.ncbi.nlm.nih.gov/pubmed/10580460Immune complexes were isolated by PEG precipitation and dissociated as described, using PEG concentrations shown not to precipitate free IgG.This PEG technique does not precipitate detectable quantities of free IgG to B burgdorferi as confirmed by performing immunoglobulin equivalences between serum and immune complexes....The objective of this study was to examine whether B burgdorferi–specific immune complexes can be detected during active infection using a simple specific immunologic assay.If this assay correlated with active infection it could be used in difficult-to-diagnose populations, such as seropositive people with nonspecific symptoms; early infected seronegative people without pathognomonic EM, including tick-bitten individuals; and seropositive vaccinated people who may not be protected...Unlike free antibody, which does not distinguish past from present infection, complexed antibody is more likely to reflect an active process. Therefore, we examined serum samples from 168 patients meeting criteria for LD to evaluate the B burgdorferi immune complex assay as a possible marker of active infection....The B burgdorferi immune complex assay appears to allow early diagnosis of infection before conventional antibody tests become positive...The B burgdorferi immune complexes were found in 25 of 26 patients with early seronegative erythema migrans (EM) LD...The Lyme vaccine, since it produces seropositivity, will make the diagnosis of infection in vaccinated persons even more difficult...Of those with active LD, 149 (96%) of 156 patients had detectable B burgdorferi immune complexes . In contrast, none of the patients who had recovered from LD were positive, and only 2 (1%) of 147 controls were positive...Our data show that the immune complex approach is superior to free antibody assays during the first weeks. In later stages, sensitivities may become similar. However, direct comparison between free and immune-complexed antibody assays may be misleading. Theoretically, the existence of immune complex is a marker of active disease, while free antibody is a marker of prior exposure.
Conclusion These data suggest that B burgdorferi immune complex formation is a common process in active LD. Analysis of the B burgdorferi immune complexes by a simple technique has the potential to support or exclude a diagnosis of early as well as active LD infection.
Article intégral : http://jama.ama-assn.org/cgi/content/fu ... 82/20/1942
VERSUS
Extrait (ter) http://cvi.asm.org/cgi/content/abstract/12/9/1036The Borrelia burgdorferi-specific immune complex (IC) test, which uses polyethylene glycol (PEG) precipitation to isolate ICs from serum, has been used as a research test in the laboratory diagnosis of early Lyme disease (LD) and has been proposed as a marker of active infection. We examined whether B. burgdorferi-specific antibodies were present within PEG-precipitated ICs (PEG-ICs) in patients with LD, posttreatment Lyme disease syndrome, and controls, including individuals who received the outer surface protein A (OspA) vaccine. The objective of this study was to examine the presence of B. burgdorferi-specific antibodies within serum PEG-ICs in patients with LD, patients with PTLDS, and controls and evaluate whether this test could be useful as a marker of active infection...We analyzed 112 different samples (from 83 individuals) for the presence of anti-B. burgdorferi IgG and 77 distinct samples (from 54 individuals) for the presence of anti-B. burgdorferi IgM ...The results for both IgG and IgM ELISAs from unprocessed serum and PEG-IC tests are shown in Table ...There was a high likelihood that samples that were positive by ELISA performed on unprocessed serum were positive by IC-PEG. When the results of all samples tested for IgG were evaluated, 94.7% (54/57) that were positive by serum IgG ELISA had a positive PEG-IC IgG ELISA result, while only 25% (11/44) of the samples that were negative by serum IgG ELISA had a positive PEG-IC IgG ELISA. In the PTLDS group, all samples with positive serum IgG ELISAs were also positive by PEG-IC IgG ELISA (26/26), while 64% (7/11) of the sera negative by IgG ELISA had a positive PEG-IC IgG ELISA result. In the OspA vaccinee group, 87.5% (14/16) of those unprocessed serum samples that were ELISA positive were also positive by PEG-IC. In the evaluation of IgM, the PTLDS group had 62.5% (10/16) of the serum IgM ELISA-positive samples also positive by PEG-IC IgM ELISA, while 23% (3/13) of the negative serum IgM ELISAs were positive by PEG-IC IgM ELISA. In the early-LD group, all negative serum IgM ELISA samples were also negative by PEG-IC IgM ELISA, while 75% (3/4) of the positive serum IgM ELISA samples were PEG-IC IgM ELISA positive....This study demonstrates that PEG-IC assays and serum ELISAs for antibodies to B. burgdorferi are not independent tests, as our results show that a positive PEG-IC ELISA result correlates strongly with a positive ELISA result in unprocessed serum, and that was true for a control population that was not expected to have circulating immune complexes.Another potential explanation for the findings of positive PEG-ICs in the vaccinated group is the production of anti-idiotype antibodies after vaccination, which would form circulating immune complexes with the anti-OspA antibodies. If this hypothesis were correct, the precipitated immunoglobulins would be part of immune complexes. As similar anti-idiotypic immune complexes could also be formed in patients after clearing of the infection, these complexes would still present a problem for the use of this test as a possible marker of infection, as precipitated antibodies would not necessarily represent antibody-antigen complex.
In conclusion, this study presents evidence contrary to the use of PEG-IC combined with standard ELISA as a marker of active infection in patients with persistent symptoms
Article integral : http://cvi.asm.org/cgi/content/full/12/9/1036
Si j'interprete bien ,ds le 1 er cas, en primo infection,séronégativité Ac "classique" en cas d'EM alors
qu'on retrouve des complexes immuns d'ou utilité de les detecter(en extrapolant)en
primo infection en cas d'absence d'EM ,avant séroconversion ou devant des signes
non spécifiques versus une corrélation parfaite entre serologie classique Ac et détection d'ICs ds la seconde,
tjrs en primo infection
Pour les phases plus avancées,bcp de "si" ,de conditionnel pour arriver à des conclusions
relativement divergentes
A 5 ans d'écart , il est étonnant que des travaux récents faisant appel à des travaux plus anciens
arrivent à des conclusions quasi opposées ou "de l'Art de faire des ronds dans l'eau " ...
mais peut etre que je comprends mal la Dre Marques ?
Pour ceux qui ne voudraient que survoler , les conclusions (seules) sont suffisamment parlantes !
===>