Abstract: A method of investigating the monotypia of a population of T-cells comprising detecting expression of the T cell receptor beta chain constant region TRBC1 and TRBC2, and/or the T cell receptor gamma chain constant region TRGC1 and TRGC, in a population of T-cells.

Abstract: The present invention provides a method of determining the disease status in a subject, the method comprising: a) obtaining sequence data for the T-cell and/or B-cell receptor repertoire in a sample obtained from a subject; b) determining a data set of overlapping k-mer frequencies in the sequence data obtained in a); c) reducing data dimensionality of the data set of k-mer frequencies determined in b) to generate a reduced data set of k-mer frequencies; d) classifying the sample according to disease status based on the reduced data set determined in c) by performing any suitable form of statistical analysis, including, but not limited to, cluster analysis, on the reduced data set; and e) optionally applying the approach described in a) to d) to classify samples of unknown disease status on the basis of their similarity to samples of known disease status.