Parainfluenza virus type 3 Ab in allogeneic hematopoietic cell transplant recipients: factors influencing post-transplant Ab titers and associated outcomes

Abstract

Parainfluenza virus type 3 (PIV-3) can cause severe respiratory illness among hematopoietic cell transplantation (HCT) recipients. Factors associated with PIV-3-specific Ab level, and the association between PIV-3 Ab levels and clinical outcomes in HCT recipients who acquire PIV-3 infection, are unknown. We evaluated PIV-3-specific hemagglutination inhibition Ab levels and clinical outcomes among 172 patients with PIV-3 infection following HCT. In a multivariable linear regression model, high post-transplantation Ab levels were independently associated with higher pre-transplantation recipient titer (mean difference 0.38 (95% confidence interval (CI), 0.26, 0.50), P<0.001). Significant associations between pre-HCT Ab titers in both patients and donors and occurrence of lower respiratory tract disease (LRD) after HCT were not observed. In conclusion, low pre-transplantation titers are associated with low Ab levels after HCT. The relationship between PIV-3 Ab levels and outcomes remain uncertain. Further study is needed to prospectively evaluate the dynamics of PIV-3-specific Ab responses and the relative contribution of PIV-3-specific Ab to protection from infection acquisition and progression to LRD.

Figure 1

Distribution of PIV-3 HAI antibody titers (expressed as reciprocal log₂ values) for patients with URI alone and LRD. Each group indicates patient antibody titer: Left, before transplantation (Median titer (Log₂): 6.0 [n = 124] and 6.0 [n=42] in patients with URI alone and with LRD, respectively, p = 0.66); Second from the left, donor antibody titer before transplantation (Median titer (Log₂): 7.0 [n = 31] and 7.0 [n=16], p = 0.81); Third from the left, patient antibody titer before diagnosis (URI or LRD) (Median titer (Log₂): 6.0 [n = 126] and 6.0 [n=46], p = 0.74); Right, before URI (Median titer (Log₂): 6.0 [n = 126] and 6.5 [n=20], p = 0.57). The median is indicated by the center line, and the first and third quartile define the upper and lower edges of the box. The extending lines illustrate the extreme values (to 1.5 times the inter-quartile range from the upper or lower quartiles) and outlines are plotted individually.

Figure 2

Cumulative incidence of PIV-3 LRD by patient pre-transplantation HAI antibody titers above or below 5 (Log₂) (closest to the lowest quartile) (day 30, p = 0.11; day 90, p = 0.12) (There were 166 patients at risk by day 30 and 160 patients at risk by day 90). URI: upper respiratory tract infection; LRD: lower respiratory tract disease; Ab: antibody.