# LY-H as a potential screening biomarker for lymphocyte activation in peripheral blood

## TL;DR

This study shows that LY-H, a new lymphocyte parameter, can help detect lymphocyte activation in blood, improving accuracy over traditional methods.

## Contribution

Introduces LY-H as a novel biomarker for identifying reactive lymphocytes in peripheral blood.

## Key findings

- LY-H levels were significantly higher in individuals with reactive lymphocytes compared to lymphoma, ALL, and CLL groups.
- LY-H strongly correlates with the percentage of reactive lymphocytes and is an independent predictor of their presence.
- LY-H demonstrated high screening value with AUC values above 0.84 for distinguishing reactive lymphocytes.

## Abstract

Viral infections often cause morphological changes in peripheral blood lymphocytes. While the presence of reactive lymphocytes in blood smears reflects lymphocyte activation, their identification is often affected by morphological heterogeneity and observer subjectivity. This study evaluates the correlation between LY-H, defined as the vector sum of lymphocyte parameters LY-Y and LY-Z, and the presence of reactive lymphocytes in peripheral blood smears, exploring its potential as a screening marker for lymphocyte activation.

Data from 404 individuals were collected and divided into four groups: 109 individuals with reactive lymphocytes found in peripheral blood smears (reactive lymphocyte group), 104 lymphoma patients (lymphoma group), 91 patients with acute lymphocytic leukemia (ALL group), and 100 patients with chronic lymphocytic leukemia (CLL group). Differences in LY-H among the four groups were compared. Logistic regression and smooth spline analysis were used to analyze the predictive value and correlation of lymphocyte parameters with reactive lymphocyte proportion. Receiver operating characteristic (ROC) curves were generated to evaluate the predictive value of LY-H for reactive lymphocytes detected by microscopy.

LY-H levels were significantly higher in the reactive lymphocyte group than in the other three groups (P < 0.05). A strong correlation was observed between LY-H and the percentage of reactive lymphocytes. Logistic regression analysis indicated that LY-H is an independent factor in the presence of reactive lymphocytes (ORLY-H: 1.017, 95% CI: 1.002–1.190). Compared with the lymphoma, ALL, and CLL groups, LY-H demonstrated the highest screening value, with area under the curve (AUC) values of 0.8489, 0.8831, and 0.8943, respectively.

Novel parameter LY-H correlates closely with the reactive lymphocytes identified in peripheral blood smears. It serves as a potential indicator for assessing lymphocyte activation status in clinical practice.