jueves, 22 de febrero de 2024

BB genera una respuesta IGM prolongada que controla la bacteriemia pero no impide la diseminación y la carga tisular. La respuesta IGM puede permanecer por décadas

Buenas noticias! 

Nuevos avances en la investigación sobre Lyme persistente que obligará  a los CDC a reconsiderar su indicación de que IGM positivo después de de 4ta o 6ta semana  indica un falso positivo. Eso no es cierto al menos en todos los casos.

Anexo el abstract del artículo.

BB genera una respuesta IGM prolongada que controla la bacteriemia pero no impide la diseminación y la carga tisular. La respuesta IGM puede permanecer por décadas

Infection with Borrelia burgdorferi causes Lyme disease in humans. In small rodents, the natural reservoir species of this spirochete, infections lead to only modest disease manifestations, despite causing persistence infection. Although B cell responses are central for controlling bacterial tissue burden and disease manifestations, they lack classical aspects of T-dependent responses, such as sustained IgG affinity maturation and longevity, corresponding with a rapid collapse of germinal centers. Instead, the Ab response is characterized by strong and ongoing secretion of IgM, whose origins and impact on protective immunity to B. burgdorferi remain unknown. In this article, we demonstrate that B. burgdorferi infection–induced IgM in mice was produced continuously, mainly by conventional B, not B-1 cells, in a T-independent manner. Although IgM was passively protective and restricted early bacteremia, its production had no effects on bacterial dissemination into solid tissues, nor did it affect Borrelia tissue burden. The latter was controlled by the induction of bactericidal IgG, as shown comparing infections in wild type mice with those of mice lacking exclusively secreted IgM−/−, all class-switched Abs via deletion of aicda (AID−/−), and all secreted Abs (secreted IgM−/− × AID−/−). Consistent with the notion that B. burgdorferi infection drives production of IgM over more tissue-penetrable IgG, we demonstrated increased short- and long-term IgM Ab responses also to a coadministered, unrelated Ag. Thus, the continued production of IgM may explain the absence of B. burgdorferi in the blood.

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