What are type II hypersenstivity reactions?

➢ Unlike type I reactions, in which antigens interact with cell-bound IgE immunoglobulins, type II reactions involve the interaction of circulating immunoglobulins with cellbound antigens. ➢ Antibody-Mediated Type II HS reactions are mediated by IgG or IgM antibodies binding to a cell membraneassociated antigen or a fixed tissues antigen (mistakenly detected as foreign) ➢ The damage caused is thus restricted to the specific cells (cytolyse) or tissues bearing the antigens. ➢ Reaction times can range from minutes to hours. ➢ Type II HS Complement Dependent Reactions (CDR) ➢ Type II HS Antibody-Dependent Cell-mediated Cytotoxicity (ADCC)