Inflammatory Challenge in Human Aggression.

Inclusion Criteria: "Aggressive Subjects" will have a current DSM-5 diagnosis of Intermittent Explosive Disorder (IED) and have a Life History of Aggression (LHA) \> 12. "Control Subjects" will not have current or past history of IED and will have LHA scores \< 11 ("Control Subjects" may have a past, but not current, history of Major Depression (MD), Generalized Anxiety Disorder (GAD), Panic Disorder (PDx), or Post-Traumatic Stress (PTSD) Disorder. Participant is between 21 and 55 years of age and is able to give informed consent. Participant is physically healthy as confirmed by medical history, physical evaluation, and (in females) a negative pregnancy test. Exclusion Criteria: Participants with a current clinically significant medical condition. Participants current co-morbid Major Depression (MD), Generalized Anxiety Disorder (GAD), Panic Disorder (PDx), or Post-Traumatic Stress (PTSD) Disorder. Participants currently taking prescribed medications for an active medical or psychiatric condition. Participants not free of prescribed medications for four weeks. Participants with Grade 2 or higher abnormalities on clinical laboratory examination (e.g., CBC with Differential, Metabolic Panel, and PT/INR/PTTa). Participants with Bradycardia (i.e., heart rate \< 50 beats/minute) or other Grade 2 or higher ECG abnormality. Participants with autoimmune conditions (e.g., asthma, psoriasis, etc.) Participants who are immunocompromised. Participants taking immunomodulatory, or anti-inflammatory, agents. Participants that are pregnant, breastfeeding, or plan to become pregnant within nine months of enrollment in the study. Female study participants of childbearing potential must remain abstinent or agree to use a highly effective form of contraception (e.g., an intrauterine device). Childbearing potential is defined as, study participants who have reached menarche and have not undergone a documented sterilization procedure (i.e., hysterectomy, bilateral oophorectomy, or salpingotomy), and have not reached menopause. Life history of bipolar disorder / schizophrenia / organic mental syndrome, or intellectual disability. Current alcohol / drug use disorder of greater than mild severity. Current suicidal ideation. History of a suicide attempt in the past year prior to study entry. Life history of \> 3 or more suicide attempts of any type. Life history of any moderately severe suicide attempt. Current or life history of homicidal ideation. Current or life history of felony assault and/or battery. Currently on parole for aggressive behavior. Allergy, or contraindication, to receiving endotoxin. Current treatment with opiates or any agents that affect pain threshold (exclusionary for the TAP). Unwilling/unable to sign informed consent document.