Pankti Mehta Profile picture
May 3, 2023 12 tweets 6 min read Read on X
☘️Antinuclear Antibodies (ANA)☘️

Here's a 🧵 on another #rheumatology test which can confuse>help if ordered without a 💭 (part 1)

Let's peek into the #immunology lab to learn more about the lab aspect of ANA 🥼🧪👀

(1/12)

#MedTwitter #LupusAwarenessMonth #MedEd Image
🤔 What do we mean by ANA??

🔹As the name suggests, they are antibodies to various nuclear components

🔹These Antigens(Ag) can be related to

1. DNA🧬: DNA, histones, nucleosomes

2. RNA: Smith, RNP, Ro, La

3. Others: ribosomal P, Ku etc

(2/12)
Which one of the following is the oldest test to detect ANA? 📜

(3/12)
1️⃣LE cells indeed!
Discovered in 1948,
LE cells are nothing but phagocytes that have eaten up the antibody bound nuclear material of another cell

(4/12)

pubmed.ncbi.nlm.nih.gov/18921142/ Image
🤷How do we test for LE cells?

💉🩸➡️ Shake 🪇 vigorously for leukocytes to rupture & release nuclear material ➡️incubate for ANAs to bind to this material & phagocytes to eat🍴 these up➡️centrifuge➡️buffy coat ➡️stain and observe🔬

(5/12)
LE cell assay has now given way to more sophisticated tests⏬

2️⃣Indirect immunofluorescence assay(IFA) is an old test but 🧓is🪙!

📜Initially, rodent liver cells were used but now Hep2 cells are used for the assay 🐀

surl.li/gubjw

(6/12) Image
🤷What do we mean by IFA??
Let's break it down

🔹Hep2 cells are fixed on a slide

🧐Why hep2 cells: large nuclei + presence of dividing cells✅ for ANA🔬

🔹+ serum in appropriate dilution (remember pro/post zone phenomena!)

ANA if present will bind to the Hep2 cells

(7/12) Image
🔹+ fluorescent tagged anti-human or 'secondary' antibodies (YES, that's why it's called indirect immunofluorescence!!)

4. Observe under a special fluorescent 🔬

(8/12) Image
It tells you 3️⃣things
1. Titre- dilution at which ANA is positive, usually done in 1:80 or 1:100

2. Intensity of staining

3. Pattern- a specific staining pattern helps identify the type of antigen

ps: it's like fireflies on a slide 😍
(9/12)
IFA can also detect Ab to cytoplasmic Ag hence ANA is better called 'Anti Cell antibodies'

IFA is the 🪙 standard but results depend on

🔹Quality of cell fixation
🔹Reagents
🔹Observer dependent

Hence we have newer tests (ELISA, CIA, FEIA, ALBIA etc)

(10/12)
3️⃣ ELISA

A mix of nuclear Ag coated on a plate

Hep2 extract: 👍 sensitivity, 👎 specificity

Mix of separate Ag: 👎 sensitivity, 👍 specificity

Why?
🔹Different Ag may compete for binding🍽️
🔹3D structure of Ag may change

Also, specific Ag can't be determined

(11/12) Image
In summary, IFA helps detect ANA positivity, the titre, intensity and the ANA pattern! Hence it's the method of choice for ANA testing.

We'll be dealing with patterns and diseases in part 2 of ANA!!

📖nature.com/articles/nrrhe…

📖nature.com/articles/s4158…

(12/12)

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How to approach a patient with #angioedema? 🧐 🧵

#MedTwitter

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♦️There are two broad mechanisms of angioedema

1️⃣ Histamine mediated or #allergy 🤧
2️⃣ Bradykinin mediated 🥵

The management depends on the underlying mechanism !

Also before anything, secure the AIRWAY if needed 🫁

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✏️What are the possible etiologies ?
🔹Allergic 🤧
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Jul 4
Facial rashes that look like lupus but are not ! 🧵🦋

1. Rosacea 🥵
🔹Look for telangiectasia
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2. Seborrheic dermatitis

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Jun 15, 2023
🫁How to interpret pulmonary function tests ??🫁

I'm not a pulmonologist but have to deal with a fair share ILDs,
here's a simple approach useful in the clinic especially for non pulmonary specialists

(1/7)

#MedTwitter #RheumTwitter #MedEd Image
1️⃣Is the test valid?

You need to check for three things

🌬️ Effort
✅The time volume curve forms a plateau in 1-2 seconds
✅ sustained expiration for 6 seconds!

(2/7) Image
➰Flow loops

✅ for artefacts/abnormalities 📷⤵️

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Jun 13, 2023
🔹Relapsing Polychondritis🔹

Important takeaways from an excellent presentation by @Lupusreference @eular_org #EULAR2023

#MedTwitter #RheumTwitter
🔹Rare disease
🔹Middle aged adults
🔹No♀️ predominance

👂👂👂👂
It's typically characterized by:
🥵Red/swollen
👂Spares the lobule
🤕Painful
⏳lasts >48 hrs
❌ ear discharge (infection)
❌ necrosis/purpura (CAPS)

📷⤵️Prone to erroneous diagnosis!! ImageImage
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Jun 6, 2023
Doctor: Where is the pain?

Patient: Pain pain everywhere!

❔How do we approach a patient with multiple joint pains❔

(1/12)
#polyarthritis #MedTwitter #MedEd #RheumTwitter Image
1️⃣ Is it polyarthritis?

First, you want to make sure it's polyarthritis - multiple (>4 joints) pain WITH SWELLING

& NOT 🚫

🔹Polyarthralgia⏩ pain WITHOUT swelling
🔹Widespread pain
🔹Myalgia
🔹Bone pain
🔹Neuropathic pain

Let's deal with polyarthritis ⏬

(2/12)
2️⃣ Is it acute or chronic??

Acute<6 weeks

🔹 Infections- gonococcal, infective endocarditis, rheumatic fever, lyme disease, viral

🔹Elderly RA, ANCA vasculitis, paraneoplastic

(3/12)

#MedTwitter
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It's #WorldEnvironmentDay2023 & I thought why not discuss the influence of air pollution🏭 on various rheumatic diseases

The association of 🏭 is obvious with lung diseases, malignancies & skin problems

But, we have to understand that the effects are deeper than that😦
Particulate matter (PM10) is inhaled & affects the upper bronchi ⏩ local inflammation

Fine & ultrafine PM reach the alveoli & circulation ⏩ systemic effects

Levels of inflammatory markers ∝ exposure to 🏭

pubmed.ncbi.nlm.nih.gov/19687019/

pubmed.ncbi.nlm.nih.gov/33470401/ ImageImage
Does it increase the risk of disease development?

Yes!

In a study from Italy, exposure to PM 10 increased the risk of RA & other immune mediated diseases

pubmed.ncbi.nlm.nih.gov/35292563/aa Image
Read 6 tweets

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