Lymphocyte counts for all subjects were determined in peripheral blood samples, using a differential blood count. Subjects who reported taking antibiotics or steroids at the time of blood collection were excluded. Measurements for the GWAS were collected between 1996 and 1997, and the lymphocyte count data were included in previous studies (25,64). One clear outlier individual with a very low lymphocyte count (456 lymphocytes/μl) was removed from the study. We note that 47 of the 462 individuals included in the GWAS were diagnosed with asthma at the time of data collection. Lymphocyte count measurements for the gene expression profiling study were collected between 2006 and 2009. Fourteen of the 95 individuals ultimately included in the expression study were ever diagnosed with asthma. The absolute lymphocyte counts (cells/μl) were natural log-transformed and age-adjusted within each study (GWAS and gene expression profiling, respectively) separately.
