| Probe | Overview |
| Ig DNA | Unrearranged DNA shows as a single line. Rearranged DNA shows as a smear. |
| I mRNA | When T cell help ( CD40-CD40L) interaction occurs there is DNA rearrangement such that VH is joined to Cε; Iε is removed from the genome and the mRNA no longer contains it. If I mRNA is not excised, but nonfunctioning immunoglobulin is still produced, then cytokine receptors are functioning but CD40/CD40L interaction is askew. |