The invention is based on the discovery of methods for purification of an acid active hyaluronidase found in human plasma (hpHAse), including both biochemical and immunoaffinity purification methods. The method of immunoaffinity purification of the invention is based on the discovery of a method for identifying antibodies that specifically bind native hpHAse (anti-native hpHAse antibodies), and anti-native hpHAse antibodies identified by this screening method. The invention also features an assay for sensitive detection of HAse activity using biotinylated hyaluronic acid (bHA). Purification and characterization of hpHAse lead to the inventors' additional discovery that hpHAse is encoded by the LuCa-1 gene, which gene is present in the human chromosome at 3p21.3, a region associated with tumor suppression. The invention additionally features methods of treating tumor-bearing patients by administration of hpHAse and/or transformation of cells with hpHAse-encoding DNA.