Lymphocyte

“ Sharply to be distinguished from the lymphocytes is the second group: the "large mononuclear leucocytes." These are large cells about twice to three times the size of the erythrocytes. They possess a large oval nucleus, as a rule eccentrically situated and staining feebly, and a relatively abundant protoplasm. The latter is free from granulations, feebly basophil, and in contrast to the protoplasm of the lymphocytes stains less deeply than the nucleus. This group is present in normal blood in but small numbers (about 1%) . ”

“ Very constant also is a marked absolute, and often a relative, increase of eosinophiles and basophiles. Polymorphonuclear neutrophiles and lymphocytes are relatively decreased.
[p. 210] The red cells show the changes characteristic of a severe secondary anemia, except that nucleated reds are commonly abundant; in fact, no other disease gives so many. They are chiefly of the normoblastic type. Megaloblasts are uncommon. Blood-plaques are generally increased.
2. Lymphatic Leukemia.—This form may be either acute or chronic. There is marked loss of hemoglobin and red corpuscles. ”

“ Small portions of the peripheral substance may repeatedly bud off, especially in the large forms, and circulate in the blood as free elements. In stained specimens, especially from lymphatic leukæmia, these forms, which completely resemble the protoplasm of the lymphocytes in their staining, may from their nature and origin be readily recognised. ”

“ Like blood it clots, but clots badly, only forming a soft clot which quickly contracts. The lymph collected from a lymphatic before it has passed through a lymph gland contains a few leucocytes, and though the number of lymphocytes is greater in the lymph after it has flowed through a gland it is never very great. In normal states there are no red blood corpuscles.
The total solids amount to 3.6 to 5.7%, the variations depending upon the amount of protein present. The lymph during hunger contains only a minute quantity of fat. ”

“ T lymphocytes: also called T cell. They are an important type of lymphocytes that maintain the immune system and are essential to fight against pathogenic microorganisms. There are two main types of T lymphocytes, Cytotoxic T cell (Tc) and the T helper cells (Th) . The Tc look for antigen infected cells in the body. When a Tc recognizes an antigen bound to a cell, it adheres to the surface of the infected cell and produces toxic molecules, killing the cell. ”

“ Corresponding to the absence of contractility in the lymphocytes it is also observed that in inflammatory processes in contradistinction to the polynuclear neutro-and oxyphils, the lymphocytes are not able to pass through the vessel wall. A very interesting experiment on this point was described by Neumann years ago. Neumann produced suppuration in a patient with lymphatic leukæmia, in whom the blood contained only a [Pg 105] very small number of polynuclear cells. ”

“ Large and small lymphocytes, each of which has a round voluminous nucleus and a narrow border, and contains a non-granular protoplasm; their proportion varies between 22 per cent. and 25 per cent.:
Polynuclear leucocytes or polymorphous leucocytes with a single nucleus, which originate in bone marrow, stain best with neutral colours, and are present in the proportion of 70 per cent. ”

“ They [Pg 79] are about as large as the small lymphocytes, possess a rounded deeply stained nucleus, and a small shell of protoplasm studded with a neutrophil granulation. The relatively deep stain of the nucleus and the small share of the protoplasm in the total cell body prevent confusion with the small forms of myelocytes, which never reach such small dimensions. The neutrophil pseudolymphocytes are exceedingly infrequent, and represent products of division of the polynuclear cells; they were first described by Ehrlich in a case of hemorrhagic small-pox. ”

“ The difference lies in the kind of leucocytes present in excess in the blood, blood-forming organs and deposits in the tissues. In the one form these are lymphocytes, which are found in health mainly in the marrow, the blood itself, the lymph glands and in the lymphatic tissue round the alimentary canal; in the other they are the kinds of leucocytes normally found in the bone-marrow-myelocytes, neutrophile, basophile and eosinophile, and polymorphonuclear cells, also neutrophile, basophile and eosinophile. ”

“ It has been observed that, in the case of reptiles which lack definite lymphatic glands (which function in man as formative centers of lymphocytes or white blood corpuscles) , the thymus is extraordinarily developed and abounds in lymphoid cells. It has also been observed that the formation of lymphocytes in the lymphatic glands is regulated by the digestive process; for, after digestion, the activity of these glands increases and the formation of leucocytes is accelerated. ”

“ On investigating the conditions under which in healthy individuals an increased number of lymphocytes enter the blood-stream, we have in the first place to notice the digestive canal, whose wall contains a thick layer of lymphatic tissue. According to the results of Rieder the proportion of the lymphocytes to polynuclears is practically normal in the leucocytosis of digestion, indeed the lymphocytes are rather in excess. ”

“ An increase of the lymphocytes from chemical stimuli is exceedingly rare, though, as is well known, a large number of substances (bacterial products, proteins, nucleins, organic extracts, and so forth) can call forth a polynuclear leucocytosis. In quite isolated cases, an increase of the lymphocytes in the blood in consequence of the injection of tuberculin into tuberculous individuals has been seen. (E. Grawitz.) ”

“ Fränkel like Uskoff regards it as the emigration of the young forms of the white blood corpuscles into the blood. He concludes logically from the diminution of the polynuclear cells in this form of disease "that the conditions of the transformation of the young forms have undergone a disturbance." But if one assumes that the lymphocytes are young forms, and the polynuclears their older stages, it is much nearer to the facts to speak, not of a disturbance in lymphatic leukæmia, but of an absolute hinderance to the ripening process. ”

“ It is quite possible that the apparent immunity to a transplanta­tion of cancer produced by Jensen, Leo Loeb, and Ehrlich and Apolant through the previous transplanta­tion of tissue in such an animal was due to the fact that this previous tissue transplanta­tion led to an increase in the number of lymphocytes in the animal. The medical side, however, lies outside of our discussion, and we must satisfy ourselves with only a passing notice. The facts show that each warm-blooded animal seems to possess a specificity whereby its lymphocytes destroy transplanted tissue taken from a foreign species. ”

“ Generally speaking, these cells, as above mentioned, are distinguished in the blood of the healthy adult by their small size, approximating to that of the red blood corpuscles. In the blood of children on the contrary larger forms are found even in health; and in lymphatic leukæmia particularly large forms occur, which are mistaken in various ways by unpractised observers. Thus Troje's "marrow cells" still figure in the literature, but have absolutely nothing to do with the marrow. They are large lymphocytes, as was established by A. Fränkel years afterwards. ”

“ Not only is there an incursion of lymphocytes into the parts but the connective tissue and endothelial cells in their vicinity revert to their embryonic state and begin the work of phagocytosis. But as a fact they have to deal with neither the effete products of molecular degeneration nor with an inert foreign body, for though virtually strangers cancer cells are by no means inactive. ”

“ These capillaries then unite to form the lymph vessels and these then convey the lymph to the subclavian veins. The lymph is a colorless fluid and contains numerous blood corpuscles known as lymphocytes. But in those lymphatic vessels, which have their origin in the walls of the small intestines, the lymph, especially during digestion, contains a great amount of fat, so that it has a milky appearance, and for this reason the lymphatics of this region, have been termed lacteals. There are two main lymphatic trunks, the one on the left side is called the thoracic duct. ”

“ It is well developed at birth, continues to grow till the time of puberty, and atrophies thereafter. It controls lymphopoiesis and maintains an effective pool of circulating lymphocytes competent to react with innumerable antigenic stimuli. ”

“ Giant-cells are common in those glands which contain remnants of filariæ. Masses of lymphocytes enclosed by inflammatory or fibrous tissue are common. Eosinophile cells are also extremely common, not only in the fibrous tissue of the glands, but in other inflammatory or fibrotic conditions: in other organs living or calcified filariæ are “usually” present. Only about 33 per cent. show mikrofilariæ in the blood. The epitrochlear gland is frequently enlarged in Fiji.
Breinl has examined enlarged glands and finds loose vascular fibrous tissue with lymphocytic invasion. ”

“ Since, then, the lymphatic glands appear to require the stimulus of the digestive process to incite them to action, it is clear that in the fœtus, which lacks the digestive process, the lymphatic glands will not be stimulated to action, and that the task of furnishing lymphocytes will devolve upon the thymus. After birth, the digestive process commences and the lymphatic glands become active in response to this stimulus. ”

“ The authors have discovered that in mice and human cells, the whole parasite or its antigens have a strong capacity to induce chronic Th2-type responses that are primarily characterized by high levels of Th2 cytokines, low proliferative responses in lymphocytes, an immature and LPS-tolerogenic profile in dendritic cells, the recruitment of myeloid-derived suppressor cells, and, specially, alternatively activated macrophages. ”

“ The eosinophiles are rare or absent as the case advances. One often finds many (7-9) nodes in the polymorphonuclears.
Pellagra.—This disease may show a chloranaemia. Some authorities have stated that we have an increase in the percentage of large mononuclears but Hillman found a rather definite increase in the lymphocytes (34%) and a normal large mononuclear percentage.
Yaws.—This disease may show a moderate anaemia with a low color index. The leucocytes are about normal in number with a moderate increase in the percentage of large mononuclears. ”

“ If, moreover, as is probably the case, the lymphatics commence as closed capillaries, we have a further difficulty in explaining how the fluid is driven through the lymphatic wall. Either we must imagine the wall to be porous or there must be a greater pressure outside than inside, and it is very difficult to conceive how this is possible. As a general conclusion, then, it seems much more probable that we are here dealing with a secretory process, and that the active tissue produces some substance or substances—it may be carbonic acid—which throws the lymphatic capillary cells into activity. ”

“ The cause is always the absorption of some toxic or infective material from the periphery. This may take place in several of the acute infectious diseases, notably in scarlet fever, mumps, diphtheria and German measles, or may be the result of poisoned wounds. The lymphatic glands are also affected in constitutional diseases such as syphilis. Simple lymphadenitis usually subsides of its own accord, but if toxins are produced in the inflamed area the enlargement is obvious and painful, while if pyogenic organisms are absorbed the inflammation progresses to suppuration. ”

“ To sum up in a few words the present state of our knowledge as to lymph formation we may say that the exchange of water and salts between the blood and the tissues is probably entirely determined by processes of filtration and osmosis. Further, that the physical condition of the capillary cells is frequently altered by many chemical substances, and that in consequence it may permit exudation into the tissue spaces much more freely. In the next place, the flow of lymph from a tissue is not solely determined by the amount of the tissue fluids. ”

“ Termination of inflammation.—Like congestion, inflammation may terminate by resolution. In this case the exuded lymph undergoes chemical change, and the products are absorbed and carried off by the blood vessels and lymphatics, to be thrown out of the body by the kidneys, liver, the glands of the skin, and the other excretory organs. The cells, which have wandered into the neighboring tissues from the blood vessels, gradually disappear or become transformed into fixed cells. Those which are the result of the tissue cells, wakened into active life, follow the same course. ”

“ For my own part, I am of opinion that the small-pox is a disease of the lymphatic system only, and my opinion seems to be confirmed by the impossibility of communicating [Pg 76] the infection by inoculating with the blood. Be this as it may, it is indisputably true, that the crude lymph is sufficient to give the infection, and that there is no necessity to draw blood at the time of incision. Add to this, the frequent tumour of the lymphatic glands in the axilla soon after the operation. ”

“ The glands act as filters, arresting not only inert substances, such as blood pigment circulating in the lymph, but also living elements, such as cancer cells or bacteria. As it passes through a gland the lymph is brought into intimate contact with the leucocytes, and in bacterial infections there is always a struggle between the organisms and the leucocytes, so that the glands may be looked upon as an important line of defence, retarding or preventing the passage of bacteria and their products into the general circulation. ”