Not CLL specific, but given allergies involve our immune system and CLL can change our allergic response, this short but reasonably comprehensive overview by a panel of academic authors writing for 'The Conversation' may be of interest:
We also need to be aware that an allergic response may significantly increase our white blood cell count - particularly our eosinophil count. One bad hayfever season several years ago, my eosinophils jumped to ten times their average value, stayed high for two months and then dropped back to their average value. It hasn't happened since then.
Note particularly: "Vitamin D deficiency may increase the risk to develop allergies. Several studies show that the further away you live from the equator (hence your lower level of sunlight exposure, which is needed to make Vitamin D) – or low vitamin D blood levels increase your risk of developing allergies. But the value of vitamin D treatment for preventing allergies has yet to be demonstrated."
Photo: Do bees sneeze? Pollen covered bee on the tip of a zucchini/courgette blossom.