To detect a humoral immune response to E Coli bacteria, you would measure __ a. cytotoxicity of virus-infected cells in the lung. b. dividing T cells in the draining lymph nodes. c. plasma cytokine levels. d. serum antibody titer.

To detect a humoral immune response to E. coli bacteria, you would measure:<br /><br />d. serum antibody titer.<br /><br />The humoral immune response involves the production of antibodies by B cells. Measuring the serum antibody titer provides information about the concentration of antibodies specific to E. coli in the blood, indicating the presence and magnitude of the humoral immune response.