growth or proliferation of keratinocytes for the purposes of the definition of this invention a disease is considered to be caused at least in part by such proliferation if expert opinion is that it is or may be a contributory factor so that it would be relevant clinically to treat the disease by reducing or preventing the growth of keratinocytes the preferred diseases for treatment are those referred to above the effect of abl on the proliferation of normal human keratinocytes was studied normal keratinocytes were extracted by trypsinisation from human foreskin passaged and cultured in cdbl53 serum free medium containing hydrocortisone 50 u03bcmol l insulin 5 mg l transferrin 5 mg ml and epidermal growth factor 10 u03bcg l cell aliquots were cultured for three days at 37 u00b0 c in 5 co 2 in the presence of varying concentrations of lectin each tested in triplicate then trypsinised harvested and counted using a coulter cell counter three separate experiments were carried out the first two studied two dose ranges of agaricus bisporus lectin 1 30 u03bcg ml and 0 1 10 u03bcg ml respectively it can be seen from the results in tables 1 and 2 respectively that there was complete inhibition of proliferation of the keratinocytes at concentrations of lectin of 1 u03bcg ml or greater no obvious toxicity e g loss of adherence of cells was seen at the highest concentration tested 30 u03bcg ml table 1______________________________________effect of mushroom lectin abl on normalhuman keratinocytes in culture 3 days cell count u00b1 standard error mean all u00d7 10 sup 5______________________________________initial cell count all samples 0 593 u00b1 0210 1 u03bcg ml abl 2 862 u00b1 0 0480 3 u03bcg ml.