From John Goers 10-24-07
Keep the stocks of primary Ab's in both "large" (5mL?) and small (0.5 mL) aliquots at -80 in their buffer (PBS or saline). Then, when needed, thaw a small aliquot, mix with an equal volume of good glycerol (try to get a fresh bottle of glycerol, and then after use it's best to purge with Nitrogen for 10-15 minutes, and then store at 4C). Store all 50% glycerol stocks between uses at -20: the idea with glycerol is that you can keep the Ab's really cold (-20C) but avoid the freeze/thaw that can cause denaturation. Don't store glycerol stocks at -80C because they are still subjected to freeze/thaw. A 1 mL aliquot of 50% glycerol stock should last a long time, considering that you usually dilute it for use. When you need another, thaw another small aliquot and add glycerol etc. When the small aliquots are all used up, then re-aliquot one of the "large" -80 aliquot.
If your original primary stocks I gave you have been at 4C they are probably OK, but freeze now! Check some on a Western. But I've found unless there is rampant bacterial growth the Ab's usually weather 4C just fine. I don't keep any primay Ab's (either crude preps or affinity pure) in azide or blocking protein: if you keep them at -20 they should be fine. I don't reuse diluted Ab's unless it's within a day or two: it's so easy to make a fresh dilution I prefer that.