Lymph Information and Courses from MediaLab, Inc.

Four small mature lymphocytes are seen in this picture. Sixty percent of the cells found in normal adult spinal fluid are lymphs.

The arrow in this slide indicates the location of another example of a blast that was seen in a spinal fluid sample. Notice the two prominent nucleoli in the nucleus of this blast. The other three cells in the field are mature lymphs. Notice that the chromatin pattern in the mature lymphs is more clumped than the chromatin in the blast cells.

Rouquette C. Berche P. The pathogenesis of infection by Listeria monocytogenes Microbiologia. 12:245-58, 1996 Listeria monocytogenes is a Gram-positive bacterium responsible for severe infections in human and a large variety of animal species. It is a facultative intracellular pathogen which invades macrophages and most tissue cells of infected hosts where it can proliferate. The molecular basis of this intracellular parasitism has been to a large extent elucidated. The virulence factors, including internalin, listeriolysin O, phospholipases and a bacterial surface protein, ActA, are encoded by chromosomal genes organized in operons. Following internalisation into host cells, the bacteria escape from the phagosomal compartment and enter the cytoplasm. They then spread from cell to cell by a process involving actin polymerisation. In infected hosts, the bacteria cross the intestinal wall at Peyer's patches to invade the mesenteric lymph nodes and the blood. The main target organ is the liver, where the bacteria multiply inside hepatocytes. Early recruitment of polymorphonuclear cells lead to hepatocyte lysis, and thereby bacterial release This causes prolonged septicaemia, particularly in immunocompromised hosts, thus exposing the placenta and brain to infection. The prognosis of listeriosis depends on the severity of meningoencephalitis, due to the elective location of foci of infection in the brain stem (rhombencephalitis). Despite bactericidal antibiotic therapy, the overall mortality is still high (25 to 30%).

Most likely means of dissemination: In a solid state Primary route of entry: Inhalation (also ingestion and absorption) General signs and symptoms: Early symptoms are flu-like—chills, fever, nausea, and swelling of lymph nodes.

At times it can be very difficult to differentiate monocytes from large lymphocytes.Monocytes may be mistaken for large lymphs when their cytoplasm stains too lightly, when the characteristic granules are indistinct, or when the nucleus is rounded or only slightly indented.Sometimes a cell will have the nucleus of a lymphocyte and the cytoplasm of a monocyte, or some other confusing combination of characteristics.In order to properly identify the cell, it is necessary to weigh all of the characteristics together to determine which cell type it most resembles.Even then it is occasionally necessary to judge the cell on the basis of the company it keeps.For instance, if there are many monocytes, but few large lymphocytes around, the confusing cell is probably a mono.

A 14 year-old boy came to the physician's office with a sore throat that progressively worsened over a three day period. His posterior pharynx was swollen ,shiney and erythematous. The boy complained of pain on swallowing. His temperature was 98.5F. A rapid direct streptococcal antigen test was positive. However, his symptoms did not subside over the next two days while on antibiotic therapy. Anorexia and nausea were persistent and compounded by a frontal headache. Cervical lymph nodes became noticeably enlarged. The results of the CBC were: WBC 11.9/mm3 with 17% segmented neutrophils, 5% bands, 72%(60% atypical--see photograph)lymphocytes and 6%monocytes. All red cell findings were normal. A monospot test was positive. This is a case of group-A streptococcal infection superimposed on infectious mononucleosis. Symptoms subsided in 3 weeks following completion of the antibiotic therapy.