... and 3 to a foreign particle i.e. antigens. Here, the complement proteins work together with antibodies to enhance the removal of antigen-antibody complexes from the body. Another common pathway is the alternative pathway. This is of major importance in host defence against bacterial infection as it is activated by invading microorganisms and does not require antibody, therefore this pathway is antibody independent. It provides an amplification loop for the classical pathway of complement activation as one of the activated components of the classical pathway can also initiate the alternative pathway. The third and final pathway is the lectin-mediated pathway. This pathway is activated by the binding of a mannose-binding protein present in blood plasma to mannose-containing carbohydrates on the surface of bacteria or viruses. For the purpose of the experiment undertaken, I will only be considering the classical and alternative pathways from now on. The classical pathway links to the adaptive ...

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