DEAR DR. ROACH: I had a splenectomy in 2012 because an oncologist thought I had NK lymphoma. After pathology, I was informed that I had an unusual immune system with a lot of NK cells, but no cancer. I was very happy, but I’m wondering how to take care of myself now that I don’t have a spleen. I’m going to be 70 years old next month. — R.L.

ANSWER: NK (natural killer) cells are a subtype of lymphocytes, a white blood cell. Leukemias and lymphomas of NK cells are unusual. The cells are important for immunity — especially for viruses and possibly for cancers. Unlike T cells and B cells, they “know” how to recognize tumor cells and virally infected cells without having seen them before. Having too few NK cells predisposes a person to viral infections, so let us hope that your having many of them is protecting you.

The spleen has important functions in immunity and in removing worn-out red blood cells. The liver takes over some of the spleen’s job after the spleen’s removal, but people without a functioning spleen are at risk for certain infections. Some of these can be immunized against, especially pneumococcus, a major cause of blood infections, pneumonia and meningitis. You already should have had two vaccines for pneumococcus: the PPSV23 and the PCV13. If you haven’t or aren’t sure, you should talk to your doctor about getting them.

A meningococcal vaccine also is recommended to prevent a common type of meningitis. It’s especially important for you to get your yearly flu vaccine.

Finally, it’s a good idea to get a medical alert bracelet (for “splenectomy”).

DEAR DR. ROACH: As we all know, a good night’s rest is very important to overall health. In my case, if I can get through the night without my nose getting congested or plugged up, everything is fine. But on many nights, at some point overnight, one or both of my nostrils eventually plug. And I can’t sleep breathing through only one nostril or my mouth, as it will become bone dry, forcing me to get up and use an over-the-counter decongestant. Overuse of these OTC decongestants isn’t a good thing, either. Any suggestions? Please advise. — J.H.

ANSWER: Nasal congestion is a common problem, and people frequently complain of it being worse at night. The first concern I have is whether you are being exposed to something at nighttime that is causing the congestion. Allergens that get on your face and clothes can worsen symptoms at night, so it can help to change clothes and wash your face when you get home. Some people even need to shower and wash their hair. Dust mites can be a problem; special coverings for pillows and mattresses can solve that problem. Pets, curtains and rugs are frequent reservoirs for home allergens. An allergist may be necessary to test to see whether you are allergic to something you can avoid.

OTC decongestants, especially those with oxymetazoline (such as Afrin) can cause terrible withdrawal symptoms if overused. If medication is necessary, there are better options, including antihistamine nasal sprays, mast cell stabilizers and steroids. But it’s absolutely worth your while to do what you can to avoid allergens if possible, rather than take medication to treat the symptoms.

The booklet on asthma and its control explains this illness in detail. Readers can obtain a copy by writing: Dr. Roach — No. 602, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Health newsletters may be ordered from www.rbmamall.com.