DISEASE CHARACTERISTICS:

• Diagnosis of acute graft-versus-host disease (aGVHD) meeting the following criteria:

  • Steroid-refractory and meeting any of the following organ-staging criteria:

    • No change in the stage of skin aGVHD after treatment with methylprednisolone at a dose of 2 mg/kg per day or more for 1 week
    • Progression of aGVHD of skin by at least 1 stage OR no response of visceral (liver, GI) aGVHD despite treatment with methylprednisolone at a dose of 2 mg/kg per day or more for at least 72 hours
    • Progression of visceral aGVHD despite treatment with methylprednisolone at a dose of 2 mg/kg per day or more for at least 48 hours
    • Progression of visceral aGVHD to stage 4 after treatment with methylprednisolone at a dose of 2 mg/kg per day or more for 24 hours

  • Grade II-IV aGVHD requiring systemic therapy within 24-48 hours of diagnosis

    • Biopsy confirmation of aGVHD is strongly recommended but not required
  • No isolated upper gastrointestinal GVHD as sole manifestation of aGVHD
  • No isolated grade I or II skin GVHD as sole manifestation of aGVHD
  • Patients must have received prior corticosteroids at a dose of 2 mg/kg/day or more for at least 72 hours as first-line aGVHD treatment

• Have undergone hematopoietic stem cell transplantation for any indication and from any allogeneic graft and donor type (i.e., marrow or peripheral blood, matched-related or matched-unrelated) within the past 100 days

  • Absolute neutrophil count > 500/mm^3 times 3 days (must have evidence of engraftment)
  • No prior autologous or syngeneic transplantation
• No chronic GVHD, defined as GVHD occurring beyond 100 days of the hematopoietic transplant
• No development of GVHD after prior donor lymphocyte infusion
• No post-transplantation lymphoproliferative disorder

• Patients failing to respond to second-line aGVHD treatment with infliximab or other second-line therapy are allowed

  • Rituximab is administered as 3rd-line aGVHD therapy

PATIENT CHARACTERISTICS:

• See Disease Characteristics
• Karnofsky performance status 30-100%
• Not pregnant or nursing
• Fertile patients must use effective contraception during and for 6 months after completion of study therapy

• No uncontrolled infection (i.e., documented bacterial, viral, or fungal infection within 72 hours prior to study entry)

  • Concurrent prophylactic, empiric, or therapeutic use of antibiotics (i.e., taken concurrently for a controlled infection) allowed
  • Clostridium difficile infection allowed

• More than 8 weeks since documentation of any of the following opportunistic infections:

  • Pneumocystis carinii
  • Aspergillosis
  • Histoplasmosis
  • Atypical mycobacterium infection
  • Other pathogenic molds or fungi
• No hypotension believed to be secondary to sepsis syndrome or heart failure requiring > 1 inotropic agent, or dopamine > 5 mcg/kg/min for blood pressure support
• No mechanical ventilatory support
• No relapsed, refractory, or second malignancies at the time of study entry
• No prior grade IV severe adverse reaction to rituximab
• No allergy to murine products
• No documented HIV infection
• No grade IV renal, hepatic, pulmonary, or neurologic toxicity
• No congestive heart failure, defined as cardiac dysfunction requiring inotropic support other than dopamine at ≤ 5 mcg/kg/min

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior rituximab in the conditioning regimen for hematopoietic stem cell transplantation
• No prior prophylactic immunosuppression tapered or stopped for treatment of leukemia relapse or minimal residual disease
• More than 2 weeks since other prior investigational agents for GVHD treatment or prophylaxis