The cluster formation of CD(4)Ly cells (a subpopulation of T lymphocyt
es) in suspension was examined. CD(4)Ly cells were prepared from blood
taken from cancer patients and from healthy counterparts (blood donor
s). CD(4)Ly cells taken from cancer patients formed tightly bound clus
ters in suspension with corresponding tumour antigen or LDH (lactic de
hydrogenase) virus antigen. Cluster formation was a rare event in susp
ensions with CD(4)Ly cells taken from healthy humans. Cluster formatio
n coincides with decreased adherence of CD(4)Ly to solid state surface
s and suggests strong mutual interaction between CD(4)Ly. A tentative
theoretical explanation based on the Frohlich coherent vibration hypot
hesis is given.