The invention is directed to methods for determining antigen-specific lymphocytes, including T cells or B cells. In some embodiments, methods of the invention may be implemented by the steps of reacting under interaction conditions one or more antigens with lymphocytes in a plurality of subsets of a tissue sample, such as peripheral blood； sorting antigen-interacting lymphocytes from other lymphocytes； separately sequencing for each subset recombined nucleic acid encoding a segment of a TCR chain or BCR chain from a sample of T cells or B cells, respectively, prior to exposure to antigen and from a sample of T cells or B cells isolated based on their interaction with antigen, respectively, thereby forming a clonotype profile for the former sample and the latter sample for each subset； and identifying as antigen-specific lymphocytes those lymphocytes associated with a clonotype whose frequency increases in the latter sample relative to its frequency in the former sample.
