Searching for a placental derived ES-62-like molecule to explain rheumatoid arthritis amelioration in pregnancy

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Craig D. Scoville *
Devon Rasmussen
(*) Corresponding Author:
Craig D. Scoville |


The majority of women with rheumatoid arthritis (RA) experience disease amelioration during pregnancy for unclear reasons. One possible explanation pursued and described here is whether the placenta produces a protein similar to the immunomodulating protein, ES-62, excreted by filarial nematodes. This protein has also been shown to reduce disease activity in animal models of RA. Eleven human placentas were prepared and a polyclonal anti-ES-62 antiserum was used to identify if any ES-62-like molecule exists from human placental tissues. Any bands identified were then excised from the gel and sent for mass spectrometry and protein identification. The anti-serum showed consistent cross reactivity with the heavy chain from immunoglobulin G (IgG) from the eleven human placentas by mass spectrometry. No primary sequence homology between the heavy chain of IgG and ES-62 was identified. The placenta does not produce an ES-62-like molecule. However the binding of the antiserum to the Fc region of IgG suggests that this may be a possible mechanism for rheumatoid factor production in some patients with chronic filarial infections.

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