A method of determining B-cell response to a tumor antigen, comprising: determining in vitro an antigen presenting index by comparing uptake of a first antigen to uptake of a second reference antigen by antigen presenting cells (APCs) from the subject, wherein determining in vitro the antigen presenting index comprises: (i) contacting a first portion of a biological sample comprising antigen presenting cells (APCs) obtained from the subject with the first antigen under conditions sufficient to induce uptake of the first antigen; (ii) contacting a second portion of the biological sample comprising APCs obtained from the subject with the second reference antigen under conditions sufficient to induce uptake of the antigen from the second reference antigen; and (iii) determining the ratio of uptake of the first antigen in the first portion of the biological sample to uptake of the second reference antigen in the second portion of the biological sample, wherein the antigen presenting index is a measure of the uptake of the first antigen in the APCs of the biological sample expressed as a ratio with uptake of the antigen from the second reference antigen in the APCs of the biological sample, wherein uptake is the binding or internalization of antigen by the APC, wherein the antigen presenting index of greater than one indicates increased likelihood of the presence of a tumor, wherein the APCs are B-cells, wherein the first antigen is a tumor antigen, and wherein the reference antigen is a non-tumor antigen. determining in vitro an antigen presenting index by comparing uptake of a first antigen to uptake of a second reference antigen by antigen presenting cells (APCs) from the subject, wherein determining in vitro the antigen presenting index comprises: (i) contacting a first portion of a biological sample comprising antigen presenting cells (APCs) obtained from the subject with the first antigen under conditions sufficient to induce uptake of the first antigen; (ii) contacting a second portion of the biological sample comprising APCs obtained from the subject with the second reference antigen under conditions sufficient to induce uptake of the antigen from the second reference antigen; and (iii) determining the ratio of uptake of the first antigen in the first portion of the biological sample to uptake of the second reference antigen in the second portion of the biological sample, (i) contacting a first portion of a biological sample comprising antigen presenting cells (APCs) obtained from the subject with the first antigen under conditions sufficient to induce uptake of the first antigen; (ii) contacting a second portion of the biological sample comprising APCs obtained from the subject with the second reference antigen under conditions sufficient to induce uptake of the antigen from the second reference antigen; and (iii) determining the ratio of uptake of the first antigen in the first portion of the biological sample to uptake of the second reference antigen in the second portion of the biological sample, wherein the antigen presenting index is a measure of the uptake of the first antigen in the APCs of the biological sample expressed as a ratio with uptake of the antigen from the second reference antigen in the APCs of the biological sample, wherein uptake is the binding or internalization of antigen by the APC, wherein the antigen presenting index of greater than one indicates increased likelihood of the presence of a tumor, wherein the APCs are B-cells, wherein the first antigen is a tumor antigen, and wherein the reference antigen is a non-tumor antigen.