Table 2

Assay specifications

Type	Matrix	Analyte	Standard Curve Range	Average Recovery	Average Precision
Type	Matrix	Analyte	Standard Curve Range	Average Recovery	Intra-Assay	Interassay
			ng/ml	%
Bioassay^2-a	Plasma	IL-2	0.31–1	N.A.^2-b	N.A.	24
ELISA^2-c	Plasma	IL-2	0.031–2	100	4.5	8.5
ELISA^2-c	Lymph	IL-2	0.031–2	103	5.1	7.6
ELISA^2-d	Plasma	PEG-IL-2	1.56–25	108	4.2	17.3
ELISA^2-d	Lymph	PEG-IL-2	1.56–25	82	7.0	12.9

↵2-a A cell proliferation assay with IL-2-dependent murine lymphocytes (Gillis et al., 1978; Watson, 1979). Samples were assayed undiluted or with assay medium so that concentrations fall within the standard curve range.
↵2-b N.A., not available.
↵2-c A commercially available ELISA (Amersham). Samples were assayed undiluted or with 50% fetal bovine serum so that concentrations fall within the standard curve range.
↵2-d This in-house assay used a murine monoclonal antibody for capture and a horseradish peroxidase-conjugated affinity-purified rat anti-human IL-2 polyclonal antibody for detection. The assay required a 1:1 dilution of the plasma with 100% pig plasma containing 4% SDS and a 1:1 dilution of the lymph with fetal bovine serum containing 4% SDS before assay.