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Immune deficiency, intact specific antibody response, and proteinuria

Question:

3/6/2017
I was recently consulted on a patient with allergies and asthma who was hospitalized for a sinus infection which was resistant to outpatient therapy. She eventually required IV antibiotics for resolution.

In taking her history, she says she was diagnosed with an IgG subclass deficiency and environmental allergies 12 years ago and was treated for one year with immunotherapy and IVIG. She did well during this time, but had to discontinue therapy due to an insurance change. Since that time, she has been diagnosed with sinusitis and treated with antibiotics with or without prednisone approximately once every 1-2 months. She has been diagnosed with pneumonia several times as well.

She has also been diagnosed recently with membranous glomerulonephritis and at this point a workup for an underlying cause has been negative. She had a UPEP which showed nonspecific proteinuria with no evidence of bence jones protein and an SPEP which showed Immunoglobulin studies show decrease of IgG and IgA. Result has been confirmed by immunofixation.

I sent immunoglobulin levels and antibody titers which showed: total IgG level 146 mg/dl (low), IGA level of 61 mg/DL (low) and IG M of 56 mg/DL (normal). Her pneumococcal titers showed appropriate response to 9/14 serotypes (she believes she had the vaccine within the last few years). Her tetanus titers are protective but Diphtheria was absent.

I am not sure where to go from here. Her nephrologist was initially planning on treatment her with Rituximab, but is reluctant now given her immune status. I am not sure how to classify her immunodeficiency or if this is simply severe protein loss from her nephrotic syndrome. Also, would IVIG be a good choice for her? Any advice would be appreciated.

Answer:

We asked Dr. Cunningham-Rundles for her expert guidance. This is her response:
"Looks like protein loss as the IgA and IgM are retained and antibody function is preserved. She still likely spills IgG into the urine - she has proteinuria (how much?) but the urinary protein electrophoresis could not tell you what that was - which is odd. If there is protein is has to be something - how about serum albumin? It that low, too?

Sometimes memory B cell tests are helpful here as the normal retention of memory phenotypes is what you expect in this case, if she is not really particularly immune deficient. (You don’t do the entire panel, only the B cells, CD27+ B cells and isotype switched cells.)

I’d test a few more antibodies and if they look OK, I think treating the kidney with whatever the specialist wants, has to be done. You could give Ig if the other antibodies are very poor and the memory B cell phenotype says she is really impaired. When she is better that can be revisited."

Hope this helps!

Patricia McNally, MD, FAAAAI