# Potential of Enzymatically Synthesized Hemozoin Analog as Th1 Cell Adjuvant

## TL;DR

This study explores an enzymatically made hemozoin analog that boosts Th1 immune responses, showing potential as a vaccine adjuvant.

## Contribution

The novel enzymatic method using Plasmodium falciparum HDP to synthesize hemozoin analogs is introduced.

## Key findings

- Enzymatically synthesized hemozoin stimulates macrophages and human cells to produce IL-6 and IL-12p40.
- In mice, esHz with antigen increased IgG2c but not IgG1, indicating Th1 cell adjuvant potential.

## Abstract

Hemozoin (Hz) is a heme crystal produced during malaria infection that stimulates immune cells, leading to the production of cytokines and chemokines. The immunostimulatory action of Hz has previously been applied in the development of alternative adjuvants. Crystallization of hemin is a chemical approach for producing Hz. Here, we focused on an enzymatic production method for Hz using the heme detoxification protein (HDP), which catalyzes heme dimer formation from hemin in Plasmodium. We examined the immunostimulatory effects of an enzymatically synthesized analog of Hz (esHz) produced by recombinant Plasmodium falciparum HDP. Enzymatically synthesized Hz stimulates a macrophage cell line and human peripheral mononuclear cells, leading to the production of interleukin (IL)-6 and IL-12p40. In mice, subcutaneous administration of esHz together with an antigen, ovalbumin (OVA), increased the OVA-specific immunoglobulin (Ig) G2c isotype level in the serum, whereas OVA-specific IgG1 was not induced. Our findings suggest that esHz is a useful Th-1 cell adjuvant.