Fig. 4

Identified proteins differentially recognized by plasma autoantibodies between the longevous and normal groups. Human proteome microarrays were used to study the autoantibody characteristics in longevity families. A protein recognized in all three samples in one group and not recognized by any sample in another group was defined as a specifically autoantigen that represented a specifically expressed autoantibody. And an antibody with its antigen–antibody reactive signal intensity of featuring a fold change of > 1.2 (> 1.20 increased or < 0.83 decreased) between the two groups was regarded as a differentially expressed autoantibody. A two tail Student’s T-test was performed and a p-value < 0.05 was considered to be statistically significant. a The volcano plot shows the up- (red) or down-regulated (green) autoantibodies between the two groups. b Hierarchical clustering of specifically and differentially expressed autoantibodies. The color scale bar locates in the bottom, and green and red indicate decreased and increased levels of the identified autoantibodies, respectively. A1, A2 and A3, 3 replicates of the longevous group; B1, B2 and B3, 3 replicates of the normal group. c Biological processes, d cellular components and e molecular functions of GO annotation based function classification of the specifically and differentially expressed autoantibodies