( ( The allergen ) ( ( ( combines ( with ( ( ( an ( allergic antibody ) ) , ) ( a protein ) ) ) ) ( that ( ( the ( allergic person ) ) ( ( ( produces and ) releases ) ( as ( ( a ( chemical mediator ) ) ( ( causing ( an ( allergic reaction ) ) ) ( to occur ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN allergen)) (VP (VBZ combines) (PP (IN with) (NP (NP (DT an) (JJ allergic) (NN antibody)) (, ,) (NP (DT a) (NN protein)))) (SBAR (IN that) (S (NP (DT the) (JJ allergic) (NN person)) (VP (VBZ produces) (CC and) (VBZ releases) (PP (IN as) (NP (NP (DT a) (JJ chemical) (NN mediator)) (VP (VBG causing) (NP (DT an) (JJ allergic) (NN reaction)) (S (VP (TO to) (VP (VB occur))))))))))) (. .)))
The allergen combines with an allergic antibody, a protein that the allergic person produces and releases as a chemical mediator causing an allergic reaction to occur.
(ROOT (S (NP (NNS Antibodies)) (VP (VBP recognize) (CC and) (VBP combine) (PP (IN with) (NP (JJ harmful) (NNS materials))) (, ,) (PP (VBG including) (NP (NP (DT both) (JJ toxic) (NNS chemicals)) (CC and) (NP (JJ invasive) (NNS microorganisms))))) (. .)))