Young children have normally an excessive proportion of lymphocytes even to a reversal of the polymorphonuclear-lymphocyte relation of adults. This is apt to be particularly marked in hereditary syphilis. Enlarged tonsils may give rise to lymphocytosis of 10,000 to 15,000 when more than 50% of the white cells will be lymphocytes. Rickets and scurvy give a lymphocytosis.
In pellagra there is a moderate lymphocytosis, averaging 34% in about a normal count.
Varicella and mumps may also give an increase in the percentage of lymphocytes.
Malta fever is a disease which may show quite a lymphocyte increase, this going with a reduction in polymorphonuclears.
Glandular fever (Pfeiffer, 1889) is a mild acute febrile disease, the fever coming on after a short incubation period and lasting about one week. Its main characteristics,—soft enlargement of the lymphatic glands, splenomegaly, and a leucocytosis of about 20,000 with 80% lymphocytes of the lymphoblastic type and many with bilobed Rieder nuclei,—lead often to its being mistaken for lymphatic leucaemia. Throat infections, particularly Vincent’s spirillosis, are thought by some to be concerned in its genesis.
Increased Large Mononuclears
In tropical work we combine the large mononuclears and transitionals in a differential count. They are the phagocytes of animal cells or parasites. The disease in which their increase is best recognized is malaria and an increase to 15% where the blood shows moderate leucopenia is very significant. The melaniferous leucocytes of malaria are cells of this type.
Other protozoal infections, as kala-azar, trypanosomiasis and amoebiasis cause it. Filterable-virus diseases may show a mononuclear increase, thus yellow fever and dengue both give an increase about the fifth or sixth day.
In Banti’s disease there is an increase in cells of this type and a transitional increase is reported for Hodgkin’s disease.