What are "molar equivalent amounts" in a description of an immune cross-reaction assay?

From "[Folate Receptor Alpha Autoantibodies in Autism Spectrum Disorders: Diagnosis, Treatment and Prevention](https://www.mdpi.com/2075-4426/11/8/710/htm)" (2021):



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> **Figure 2. (A)** Folate receptor concentrations in milk. **(B)** Immune cross-reactivity of blocking autoantibodies against various FR antigens. *The blocking assay was performed by testing a known amount of blocking activity in serum samples from 8 different patients with molar equivalent amounts of FR antigens from milk.* Blocking activity was determined as pico moles of 3HPGA blocked and was compared to blocking in human milk antigen.
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> [![enter image description here](https://i.stack.imgur.com/VAdde.png)](https://i.stack.imgur.com/VAdde.png)
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The whole sentence in italic is cryptic to me, for instance, how can there be "a known amount of blocking activity"? Is activity measured in amounts?


But especially what are "molar equivalent amounts"? Samples of milk containing the same number of moles of the FR receptor as the number of moles of anti-FR antibodies contained in the samples taken from the 8 different patients? Thus it could be measured precisely how these antibodies react with FR receptors belonging not to the human, but to a different specie (a goat, a cow)?


