Study of Opioid Immunosuppressive Effects

Inclusion Criteria: * subjects were excluded if they had a chronic systemic illness (cardiac, renal, pulmonary, hepatic, endocrine, metabolic, or autoimmune disorders) or * a major psychiatric disorder or * if they were abusing substances other than heroin (as determined by urine drug test result). For women, pregnancy was also a reason for exclusion. Exclusion Criteria: * Control subjects with no history of drug or alcohol abuse were also excluded if they had * major medical or psychiatric disorders