Biomarkers in Blood Samples From Patients With HIV Infection and Stage III or Stage IV Hodgkin Lymphoma Undergoing Chemotherapy

DISEASE CHARACTERISTICS: * HIV-1 infection, as documented by a rapid HIV test or any FDA-approved HIV-1 enzyme or chemiluminescence immunoassay (E/CIA) test kit and confirmed by western blot at any time prior to study entry * Documentation may be serologic (positive ELISA and positive western blot), or other federally approved licensed HIV diagnostic test * Prior documentation of HIV seropositivity is acceptable * Diagnosis of untreated Hodgkin lymphoma and participation in the parent protocol SWOG-S0816, "A Phase II Trial of Response Adapted Therapy of Stage III-IV Hodgkin Lymphoma Using Early Interim FDG-PET Imaging." PATIENT CHARACTERISTICS: * No psychosocial conditions that would prevent study compliance and follow-up, as determined by the principal investigator * Willing to provide serial blood samples PRIOR CONCURRENT THERAPY: * See Disease Characteristics