Described herein is a method for determining a lymphocyte cell receptor chain sequence specific to a unique antigen, comprising: sorting a plurality of antigens into a plurality of reaction mixtures, wherein the sorting comprises adding a unique antigen of the plurality of antigens to a unique subset of the plurality of reaction mixtures such that two different unique antigens are not added to the unique subset; contacting each reaction with a biological sample comprising a plurality of lymphocytes; separating a target lymphocyte from a subset of the plurality of lymphocytes, wherein the target lymphocyte recognizes the unique antigen; after separating the target lymphocyte, sequencing nucleic acids of the target lymphocyte to obtain the lymphocyte receptor chain sequence, wherein the sequencing is performed by single-cell sequencing; and detecting the unique antigen, wherein the detecting comprises: computing a frequency of lymphocyte cells that express the lymphocyte receptor chain sequence.