Biologic response modifiers and urologic malignancies

Urinary interleukins in patients receiving intravesical Bacillus Calmette-Guerin therapy for superficial bladder cancer

Intravesical administration of Bacillus Calmette-Guerin (BCG) causes a localized cell-mediated immune response. The intensity of this inflammatory response may be gauged by measuring the levels of both interleukin-2 (IL-2) and an inhibitor of interleukin-2 (IL-2-IN) activity in the urine during the hours after a BCG instillation. The levels of urinary IL-2 and IL-2-IN in the sixth week of BCG therapy predicted the subsequent clinical course in a group of 25 patients (P less than 0.01). Measurement of urinary IL-2 and IL-2-IN activity may be used to identify accurately those patients likely to develop a tumor recurrence, thereby sparing them the risk associated with inadequately treated bladder cancer. Since IL-2 and IL-2-IN are competitive with respect to biologic activity, and since relatively high urinary levels of either IL-2 or IL-2-IN activity correlated with a favorable clinical course, the authors conclude that the presence of bioactive IL-2 in urine is not required for the prevention of recurrent superficial bladder cancer.

Urinary interleukin-2 inhibition in patients with cystitis

An inhibitor of interleukin-2 activity (IL-2-IN) is present in the urine of most patients during the acute phase of untreated bacterial cystitis (UTI). We measured urinary IL-2-IN activity in 30 adults with uncomplicated UTIs and followed the patients for an additional 6 months. Urinary IL-2-IN activity ranged between 0 and 1.97 units/mg urine creatinine (U/mg u.c.). Relatively low levels of IL-2-IN (less than 0.5 U/mg u.c.) correlated with a prior history of recurrent UTIs (p less than 0.01), and also were predictive of a subsequent UTI during the 6 month follow-up, regardless of the prior medical history (p less than 0.01). Measurement of urinary IL-2-IN during the untreated phase of a UTI may prove helpful for directing antibiotic prophylaxis against subsequent UTIs.

Measurement of serum interleukin-2 activity

The accurate measurement of serum interleukin-2 activity is crucial for assessing the efficacy and toxicity of systemic immunotherapy with recombinant interleukin-2. Incubation of serum at 56 degrees C for 30 minutes facilitates the bioassay for interleukin-2 activity by destroying the interleukin-2 inhibitory activity native to human serum. As this report will demonstrate, however, 30% to 50% of interleukin-2 activity in serum taken from patients or normal volunteers was destroyed by heating at 56 degrees C. No loss of recombinant interleukin-2 activity occurred during heating in serum-free media. The percentage of interleukin-2 activity lost at 56 degrees C varied from patient to patient and also varied with the time of exposure. Native serum interleukin-2 inhibitory activity can be removed, and interleukin-2 activity can be assessed accurately in serial dilutions of the serum beyond 1:64.