Theory 16/Immune response/Onset phase
Activation Needs an Antigen Threshold
The claim
An immune response starts above a threshold in the ratio of antigen density to receptor affinity, so low-density antigen is ignored regardless of affinity.
01Mechanism
Signalling requires enough engaged receptors; the ratio determines whether the threshold is crossed.
02Prediction
Activation should track the ratio.
03Refutation
Activation tracking affinity alone would remove density.