Dying leukocytes suspended in normal serum tend to agglutinate spontaneously into a firm "clot." This phenomenon is associated with cell lysis and the formation of long fibrous strands of DNA-protein. It seems likely that nuclear DNA-protein actually combines in some way with a fraction of the serum proteins (possibly mucoprotein).
Such leukocyte agglutination is inhibited by serum containing the L.E. cell factor. LAI is associated with nuclear changes which are characteristic of the L.E. cell phenomenon, and it is most probable that it is an expression of the L.E. cell phenomenon.
An understanding of the chemistry of LAI may lead to useful information as to the fundamental mechanism of the L.E. cell phenomenon. Without such understanding, LAI has been used to obtain collateral information concerning the L.E. cell phenomenon: namely, to rule out any important role for DNA-ase, and to confirm the importance of blood platelets. It has also been used to prepare "pure cultures" of L.E. bodies for cytochemical study.
On a clinical level, LAI may prove a useful adjunct to the standard L.E. cell tests. However, its lower level of sensitivity and occasional "false positive" reactions make it inadequate as a primary test in systemic lupus.