Multiplexed single cell immunoassay

A method for measuring the secretion level of a secreted factor of a single cell, comprising:

• contacting one or more single cells with a first plurality of first solid supports, wherein the one or more single cells are capable of secreting a plurality of secreted factors, wherein each first solid support comprises a plurality of capture probes capable of specifically binding to at least one of the plurality of secreted factors secreted by a single cell, and wherein at least two of the capture probes are capable of binding different secreted factors;
• contacting the first solid support with a plurality of secreted factor-binding reagents each capable of specifically binding to a secreted factor bound by a capture probe, wherein each of the plurality of secreted factor-binding reagents comprises a detectable moiety, or a precursor thereof, wherein secreted factor-binding reagents capable of binding the same secreted factor comprise the same detectable moiety, or a precursor thereof, and wherein secreted factor-binding reagents capable of binding different secreted factors comprise different detectable moieties, or precursors thereof;
• and
• measuring emissions of each detectable moiety of each first solid support to determine the secretion level of the at least one secreted factor secreted by each of the one or more single cells.