# Epitope analysis of an anti-mouse CCR1 monoclonal antibody S15040E using flow cytometry

## TL;DR

This study identifies the specific region on the mouse CCR1 protein that a monoclonal antibody binds to, which could help in understanding immune cell functions and developing new therapies.

## Contribution

The study identifies the conformational epitope and key amino acids in ECL2 of mCCR1 recognized by the monoclonal antibody S15040E.

## Key findings

- S15040E recognizes the extracellular loop 2 (ECL2, aa 172–197) of mouse CCR1.
- Trp176, Phe178, and Arg181 are essential for antibody recognition.
- S15040E may aid in structural analysis of mouse CCR1 to understand its function.

## Abstract

The C–C motif chemokine receptor 1 (CCR1) is widely expressed in various immune cells and plays crucial roles in the maturation and migration of immune cells. CCR1 has been considered an attractive drug target for treating autoimmune diseases and tumors. An anti-mouse CCR1 (mCCR1) monoclonal antibody (clone S15040E) has been used in various in vivo studies to identify mCCR1-positive cells by flow cytometry. However, the binding epitope has not been determined. This study investigated the binding epitope of S15040E using flow cytometry. The mCCR1 extracellular domain-substituted mutant analysis showed that S15040E recognizes the extracellular loop 2 (ECL2, aa 172–197) of mCCR1. Next, alanine (or glycine) scanning was conducted in the ECL2 region. The results revealed that Trp176, Phe178, and Arg181 are essential amino acids for the recognition by S15040E. These results showed the involvement of the ECL2 of mCCR1 in the recognition by S15040E.

•An anti-mouse CCR1 monoclonal antibody (S15040E) has been used in flow cytometry.•S15040E recognizes a conformational epitope on the extracellular loop 2 (ECL2, aa 172–197) of mouse CCR1.•The Trp176, Phe178, Arg181, and Cys183 in ECL2 are essential for the recognition by S15040E.•S15040E may contribute to the structural analysis of mouse CCR1 to understand the function.

An anti-mouse CCR1 monoclonal antibody (S15040E) has been used in flow cytometry.

S15040E recognizes a conformational epitope on the extracellular loop 2 (ECL2, aa 172–197) of mouse CCR1.

The Trp176, Phe178, Arg181, and Cys183 in ECL2 are essential for the recognition by S15040E.

S15040E may contribute to the structural analysis of mouse CCR1 to understand the function.