Allele specific antibody response against the polymorphic system of HLA is the
allogeneic response marker determining the immunological risk for graft acceptance
before and after organ transplantation and therefore routinely studied during the patient’s
workup. Experimentally, bead bound antigen- antibody reactions are detected using
a special multicolor flow cytometer (Luminex). Routinely for each sample, antibody
responses against 96 different HLA antigen groups are measured simultaneously and
a 96-dimensional immune response vector is created. Under a common experimental
protocol, using unsupervised clustering algorithms, we analyzed these immune intensity
vectors of anti HLA class II responses from a dataset of 1,748 patients before or after
renal transplantation residing in a single country. Each patient contributes only one
serum sample in the analysis. A population view of linear correlations of hierarchically
ordered fluorescence intensities reveals patterns in human immune responses with
striking similarities with the previously described CREGs but also brings new information
on the antigenic properties of class II HLA molecules. The same analysis affirms that
“public” anti-DP antigenic responses are not correlated to anti DR and anti DQ responses
which tend to cluster together. Principal Component Analysis (PCA) projections also
demonstrate ordering patterns clearly differentiating anti DP responses from anti DR
and DQ on several orthogonal planes. We conclude that a computer vision of human
alloresponse by use of several dimensionality reduction algorithms rediscovers proven
patterns of immune reactivity without any a priori assumption and might prove helpful for
a more accurate definition of public immunogenic antigenic structures of HLA molecules.
Furthermore, the use of Eigen decomposition on the Immune Response generates new
hypotheses that may guide the design of more effective patient monitoring tests