Epratuzumab and Rituximab in Treating Patients With Previously Untreated Follicular Non-Hodgkin Lymphoma

DISEASE CHARACTERISTICS:

* Histologically\* confirmed follicular non-Hodgkin lymphoma (NHL)

  * Previously untreated disease
  * WHO classification grade 1, 2, or 3a (\> 15 centroblasts per high power field with centrocytes present) that is stage III, IV, or bulky (i.e., single mass ≥ 7 cm in any unidimensional measurement) stage II disease NOTE: \*Bone marrow biopsies as the sole means of diagnosis are not acceptable, but they may be submitted in conjunction with nodal biopsies; fine-needle aspirates are not acceptable for diagnosis
* Confirmed CD20 antigen expression by flow cytometry or immunohistochemistry
* Measurable disease by physical examination or imaging studies

  * Any tumor mass \> 1 cm is acceptable
  * No nonmeasurable disease only, including any of the following:

    * Bone lesions
    * Ascites
    * Pleural/pericardial effusion
    * Lymphangitis cutis/pulmonis
    * Bone marrow (involvement by NHL should be noted)
* No known CNS involvement by lymphoma
* Required to participate in companion FDG-PET imaging study CALGB 580701

PATIENT CHARACTERISTICS:

* ECOG performance status ≤ 2
* Absolute neutrophil count ≥ 1,000/μL
* Platelet count ≥ 50,000/μL
* Patients with HIV infection are eligible provided they meet the following criteria:

  * No evidence of coinfection with hepatitis B or C
  * CD4+ cell count ≥ 400/mm\^3
  * No evidence of resistant strains of HIV
  * If not on anti-HIV therapy, HIV viral load \< 10,000 copies HIV RNA/mL
  * If on anti-HIV therapy, HIV viral load \< 50 copies HIV RNA/mL
  * No history of AIDS-defining conditions
* Not pregnant or nursing
* Fertile patients must use effective contraception during and for 3 months after completion of study therapy
* No known Human Anti-Chimeric Antibody (HACA)-positivity

PRIOR CONCURRENT THERAPY:

* No prior therapy for NHL including chemotherapy, radiotherapy, or immunotherapy (e.g., monoclonal antibody-based therapy)
* More than 2 weeks since prior corticosteroids except for maintenance therapy for non-malignant disease
* No concurrent dexamethasone or other steroids as antiemetics except for the following circumstances:

  * Treatment of acute infusion reactions according to institutional procedures
* No concurrent hormonal therapy except steroids for adrenal failure OR hormones for non-disease-related conditions (e.g., insulin for diabetes)
* No other concurrent chemotherapeutic agents