# Circulating prothymosin alpha and immunoglobulin G3 in acute rheumatic fever and rheumatic heart disease: A case-control study

## TL;DR

This study compares blood markers in patients with acute rheumatic fever and rheumatic heart disease to find better diagnostic tools.

## Contribution

The study provides new evidence on IgG3 as a potential diagnostic marker for acute rheumatic fever in low-resource settings.

## Key findings

- Total IgG3 was significantly elevated in definite ARF compared to controls, possible ARF, and chronic RHD.
- PTA levels were similar across groups, contradicting a previous report of elevated PTA in RHD.
- IgG3 elevation in ARF was observed in both serum and plasma samples from different regions.

## Abstract

The lack of specific diagnostic tests for acute rheumatic fever (ARF) and its consequence rheumatic heart disease (RHD) is a key barrier to effective control of these diseases in low resource settings.

We used immunoassays to evaluate blood prothymosin alpha (PTA) and immunoglobulin G3 (IgG3) in patients with ARF, RHD and controls using serum samples from Pakistan and plasma samples from Uganda.

Across both sets of samples, we found total IgG3 was significantly elevated in definite ARF (n = 24) compared to controls (n = 36), possible ARF (n = 15) and chronic RHD (n = 11). Whether measured in serum or plasma, PTA levels were similar across these groups.

Our findings conflict with a previous report that found PTA was elevated in RHD compared to healthy controls. In contrast, while less marked than before, we found IgG3 was elevated in ARF, extending this observation to settings where the impact of RHD is greatest.