Primary immunodeficiency - a Twitter summary from the 2012 WSAAI meeting

This summary was compiled from the tweets posted by @MatthewBowdish, an allergist/immunologist, who attended the 2012 Western Society of Allergy, Asthma and Immunology (WSAAI) meeting. The tweets were labeled #WSAAI. The text was edited and modified by me.

Primary immunodeficiency

Steven Holland discussed primary deficiency of innate immunity:

HIES

Serum IgE levels in Job's syndrom fall into normal range in 20% of patients by the time there are adults. Normal IgE does not exclude Job’s syndrome (HIES).

STAT3 mutation is found in some patients with HIES.

HIES patients can get extreme zoster infections, probably related to defect in T cell memory.

Patient with severe allergies probably don't have HIES. “True” HIES are more likely to experience mild eczema, pneumonias and fractures.

DOCK8 deficiency

DOCK8 deficiency is probably related to cytoskeletal rearrangement.

Lymphopenia is common and progressive. DOCK8 deficiency includes elevated IgE and eosinophils, IgGs are normal and IgM is low.

At least one case of DOCK8 deficiency has been picked up via newborn TREC screening. DOCK8 deficiency includes allergy, asthma, eczema, infections, cancer.

PLAD

A NEJM article (01/11/2012) on cold urticaria reported on PLCg2-associated antibody deficiency and immune dysregulation (PLAD).

Primary immunodeficiency disorders (PIDD) (click to enlarge the image):



Primary immunodeficiency screening

Dr. Steven Holland discussed the progress in primary immunodeficiency screening:

80% of SCID cases are sporadic.

How is SCID screening actually done?

Via TREC dried blood spot assays on Guthrie cards (TRECs are measured by PCR). If TRECs abnormal, then further analysis is indicated.

In first year of screening in California, 20 SCIDs/lymphopenias were found out of 500,000 live births.

Population-based screening for SCID in neonates: The winner is T-cell receptor excision circles. JACI, 2012. See the TRECs figure here: http://goo.gl/dAXHv

Severe combined immunodeficiency (SCID) - 4 groups according to T/B/NK cells (click to enlarge the image):



What is the frequency of immune deficiency in general population?

1:10,000 (SCID and non-SCID).

4 million births/year in US lead to 400 new cases of immunodeficiency per year. If all are survived, this will lead to 7200 patients in 18 years.

The rate of immunodeficiency is much higher in recurrently ill: 10%. If you select for recurrent or severe problems, the rates are even higher.

Every population is different: PIDD are common in Amish, Ashkenazi, Native Americans, Island populations, certain families, etc.

Which PIDD is most common?

Antibody (50%), T cell defects (20%), phagocyte def (20%), Complement (2%). Mnemonic: 50-20-20-2.

“Infections to know”

There are some “infections to know” because of their links to specific PIDDs:

- Pneumococcus (Ab, NFkB)
- Meningococcus (IRAK)
- Staph. abscess (CGD)
- Pseudomonas (CF)
- Burkholderia (CF, CGD). “Nothing else leads to Burkholderia cepacia bacteremia other than CGD”. If a patient has B. cepacia pneumonia, consider CGD or CF in the differential diagnosis.

Most microbes ignore us - there are 1.5 million species of fungi, 70,000 are characterized, only a few are “interested in us.”

CGD

CGD subtypes:

- X-linked (Xp21) 65%

- Autosomal p47phox (25%), p22phox (<5%), p67phox (<5%), p40phox (1 case)

 Must-know CGD infections: S aureus, S marsescens, B cepacia, Nocardia, Aspergillus, Salmonella, BCG.

“Extra credit” CGD infections: Chromobacterium violaceum, Francisella philomiragia and Granulibacter bethesdensis.

 Clinical pearl: Fulminant mulch pneumonitis is an emergency presentation of CGD.

Phagocyte immunodeficiencies (click to enlarge the image):



This summary was compiled from some of the tweets posted by @MatthewBowdish . The tweets were labeled #WSAAI and they reached more than 3,000 people. I would strongly encourage you to post updates on Twitter from the CME conferences that you are planning to attend in the future. Here is how to do it: Twitter for Physicians: How to use Twitter to keep track of the latest news and scientific meetings, and share information with colleagues and patients.

Disclaimer: The text was edited, modified, and added to by me.