Table 1.

Coding of testing levels: testing levels are assigned by the highest level of test achieved according to this table (0–5).

Level	Presence of any one of these tests
0	No laboratory tests performed
1	CBC, IgG/A/M
2	IgE, C3, C4, CH50, AH50, functional antibody response including to tetanus, polio, hepatitis B vaccine
3	Basic lymphocyte subset analysis (CD3, CD4, CD8, CD19, CD20, CD16, CD56), dihydrorhodamine test, nitroblue tetrazolium test
4	Lymphocyte cell marker CD45RO/RA, TREC qPCR, lymphocyte proliferation test, NK cytotoxicity studies
5	Comprehensive T or B cell subset with markers other than those mentioned in levels 3 and 4, protein expression of PID genes (e.g., WASP, BTK, CD40L by flow cytometry), assays of pathway activation (e.g., pSTAT3 by Western blot or flow cytometry), cytokine production (e.g., IFN-gamma level by ELISA)

CBC, complete blood count, TREC, T-cell receptor excision circle; qPCR, quantitative polymerase chain reaction.