Platelet accumulation of histamine in controls, depressed and lithium-treated patients. 
The accumulation of histamine into blood platelets of depressed patients, lithium-treated patients and controls was determined using radio-labelled histamine.  All groups had significantly different mean accumulation rates: the depressives had the lowest, the controls had the highest while the lithium-treated patients had intermediate rates.  No significant difference in histamine accumulation rates was detected between drug-free depressed patients or depressed patients receiving psychotropic medication apart from lithium.  Histamine accumulation rates of depressed patients did not appear to have been influenced by their age or severity or endogenicity of their illness; no difference in histamine accumulation was detected between those patients who had an abnormal or normal dexamethasone suppression test response.  We have concluded that while the biological significance of these results is unclear it would appear to be a very sensitive test for depression, especially in women.  It would appear that prophylactic lithium treatment increased the rate of histamine accumulation: this result is discussed with reference to histamine's association with allergic disorders.