Measurement of Humoral Immune Competence and the Risk of Sinopulmonary Infection in a Cohort of Kidney Transplant Recipients

Purpose: The aim of this study was to determine if measurement of B cell protective immunity was associated with susceptibility to sinopulmonary infection in kidney transplant recipients. Methods and Materials: A prospective cohort of 168 patients with stable graft function (median 4.1 years) underwent assessment of B-lymphocyte antigen CD19 (CD19⁺) cell number, immunoglobulin G concentration, and seroresponses to influenza vaccination upon study entry. Patients received a single dose of a trivalent, seasonal influenza vaccine. Results: After 2 years follow-up, 31 patients (18%) developed sinopulmonary infection. CD19⁺ cell number was strongly associated with future sinopulmonary infection. A higher proportion of patients with CD19⁺ cell counts below the fifth percentile for controls developed sinopulmonary infections than those above the fifth percentile, 30% (23 of 77 patients) compared with 9% (7 of 79 patients; P =.001). There was a trend toward a higher proportion of patients with reduced immunoglobulin G concentrations developing infections than in the normal range for controls, 29% (14 of 48 patients) compared with 15% (16 of 108 patients; P =.060). Influenza vaccination seroresponses were poor in patients and controls such that they could not be used to identify a subgroup of patients at high risk for the development of severe pulmonary infection. Conclusions: Monitoring B-cell numbers represents a simple, inexpensive means of stratifying transplant recipients’ risk of sinopulmonary infection.