The results of an agglutination test for antibody detection…

The results of an agglutination test for antibody detection using dilutions of patient serum are shown below. What do the results in tubes 1 through 5 represent? Tube no. 1 2 3 4 5 6 7 8 Dilution 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 Patient 0 0 + + + + + + += agglutination; 0= no agglutination