Rituximab, Cyclophosphamide, and Pegfilgrastim in Treating Patients With Leukemia or Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: * One of the following B-cell leukemias or lymphomas, as defined by World Health Organization criteria: * Chronic lymphocytic leukemia/small lymphocytic lymphoma * B-cell prolymphocytic leukemia * Lymphoplasmacytic leukemia * Marginal zone lymphoma (splenic, extranodal, or nodal) * Follicular lymphoma (grade 1 or 2) * Mantle cell lymphoma * No more than minimal (approximately 10%) morphologically identifiable cancer cells on bone marrow biopsy * When cancer cells are morphologically difficult to distinguish from normal cells, flow cytometry must show no more than 10% identifiable cancer cells * Must have received ≤ 12 months of prior cytotoxic therapy, achieving at least a partial response NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology. PATIENT CHARACTERISTICS: * ECOG performance status 0-1 * WBC ≥ 3,000/mm\^3 * Hemoglobin ≥ 10.0 g/dL * Platelet count ≥ 75,000/mm\^3 * Serum creatinine ≤ 2.0 mg/dL * Total bilirubin ≤ 2 mg/dL unless secondary to tumor * AST or ALT \< 2 times upper limit of normal * Normal (≥ 45%) left ventricular cardiac ejection fraction (determined by echocardiogram or MUGA scan) * DLCO \> 50% predicted * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No known sensitivity to E. coli-derived products (e.g. filgrastim \[G-CSF\], insulin, asparaginase, growth hormone, or recombinant interferon alfa-2b) or any treatment study drugs * No active infections requiring oral or intravenous antibiotics * No other second malignancy other than basal cell or squamous cell carcinoma of the skin or in situ carcinoma of the cervix unless the malignancy was localized and treated or resected with \> 90% probability of cure PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Prior anti-CD20 therapy allowed provided patient achieved a partial or complete response * No concurrent steroids during rituximab administration