Table 6. Correlation Coefficients (r) Between Indicators of Clinical Status and Lymphocyte Proliferative Responses to Phytohemagglutinin (PHA) (corrected for baseline ³H-thymidine uptake) in Children With Sickle Cell Disease

Variable	PHA 2.5 μg/mL	PHA 5 μg/mL	PHA 10 μg/mL	PHA 15 μg/mL
Retinol binding protein	0.242^{^a}	0.307^{^a}	0.349^{^a}	0.367^{^a}
Health score^{^b}	−0.319^{^a}	−0.272^{^a}	−0.287^{^a}	−0.326^{^a}
Pain crises	−0.252^{^a}	−0.182	−0.195	−0.195
Units of blood	−0.195	−0.243^{^a}	−0.266^{^a}	−0322^{^a}
Infections	−0.151	−0.138	−0.172	−0.042

↵^a The (r) value is significantly different from zero (P < 0.05).
↵^b Health score is the sum of the number of episodes of pain crisis, infection, hospital admission, and/or blood units received.