**3.2 B1 cells**

*Normal and Malignant B-Cell*

**Figure 4.**

*expression of CD21 B cells*.

Thus, in patients with gastric cancer, a violation of the immunological repertoire of B2 cells was established: the presence of a pronounced proportion of CD21+ B cells with weak expression, a significant number of CD23+ cells, and cases of clonal B cells. In most of the studied samples, B cells were polyclonal with a predominance of Ig-κ (**Figure 5**). When the thymus-dependent pathway of the immune response is realized, these patients will have a disruption in the synthesis of antibodies.

*Expression of CD21 antigen on B cells of blood of patient with stomach cancer. The abscissa axis is the expression of CD21; on the ordinate axis—CD19 expression, in the figure all cells of the sample, including granulocytes. Area R2, CD19+CD21+ cells, this region is located above the granulocytes, which indicates a weak* 

It is known that a B cell can be activated without the involvement of a T lymphocyte, which leads to the full development of B lymphocytes to antibody-producing forms. It is a characteristic that in this case the immunoglobulin M is synthesized predominantly [5–7]. The process of activation of B cells without T lymphocyte is provided by thymus-independent antigens of type I and II [4]. They are lipopoly-

Antibodies of IgM class are the earliest in immunogenesis and make up about 6% of all immunoglobulins; their half-life is 5–6.5 days. Approximately half of the

saccharides, polysaccharides, and proteins.

*Polyclonality of B cells with predominance of Ig-κ.*

**140**

**Figure 5.**

The population of B1 cells is the most phylogenetically ancient branch of antibody producing cells found in humans and mice. B1 lymphocytes develop in the liver of the fetus from progenitor cells. The B1 precursor, which differs from the B-line progenitor that develops primarily in the B2 population, is identified in the murine bone marrow to a lesser degree in the adult bone marrow [34]. B1 cells are considered as key players of the early humoral response against pathogens and considered primary antibody producers in response to T cell-independent type 2 antigens [44]. A specific thymus-independent response is realized by two subpopulations of B1 cells: B1a and B1b.

Both subpopulations of B1 cells are characterized by an "activated phenotype," which is manifested in the expression on their surface of costimulatory molecules CD80 and CD86. This property provides the ability of B1 lymphocytes to function as antigen-presenting cells. B1b cells are phenotypically similar to B1a cells, but they are characterized by the absence of CD5 expression. B1b lymphocytes realize an adaptive immune response, and B1a lymphocytes produce natural antibodies that are specific to microbial agents and opsonize pathogen-mediated innate immunity [45–47].

Such a B1a population of lymphocytes has the phenotype CD19+CD21lowCD23- CD5+IgM++. A number of experimental studies have revealed that immunity disorders after splenectomy primarily affect the B cell immune response, including thymus-independent (TN) type 2 antigens, which is provided by the population of B1a lymphocytes [31, 32].

Among B lymphocytes of peripheral blood of patients with gastric cancer, expressed subpopulation of CD5+ cells was noted. The number of CD19+CD5+ B cells averaged 17.7%. In 23% of patients, CD19+CD5+ lymphocytes were more than 20%, and in three patients, more than 40% of CD19+CD5+ lymphocytes were detected. Normally, the population of CD19+CD5+ B cells is no more than 10% of the total number of peripheral blood B lymphocytes. Among the B cells of the group with a higher CD19+CD5+ B lymphocyte count (more than 15%), the percentage of cells expressing CD25+ and CD21+ antigens was significantly higher; differences in the number of CD38+ B cells were found to be significant, but the range of values for one group of samples with respect to this antigen was higher. The data are presented in **Table 4**.

The presence of CD38 and CD25 antigens on circulating peripheral B cells indicates their activation. It is possible in coexpression of CD23 antigen, which was observed in a group of samples containing more than 25% of B1a lymphocytes.

A high probability of the presence of the CD19+CD23+CD38+CD5+ population (the presence of a reliable correlation relationship for B cells with the expression of CD38 and CD23 antigens, R = 0.885, p = 0.008) was established. There was also a high probability of the presence of the CD19+CD5+CD25+ population (significant


#### **Table 4.**

*Significant populations of B cells in groups of patients with stomach cancer with (CD5+) lymphocytes (group 1 ≥ 15%) and their normal content (group 2 < 15%).*

correlation for CD1+CD5+ and CD19+CD25+ B cells, R = 0.879, p = 0.05). However, in most samples (65%), the number of CD19+CD38+ B cells was insignificant—less than 15.0% (**Figure 3b**).

It is interesting to note that the expression levels of the CD5 antigen on B cells proved to be significantly weaker [region R3, (**Figure 5d**)] as compared to the expression of CD5 antigen on peripheral CD3+ T cells.

Thus, in 17.7% of patients with gastric cancer in the peripheral blood, there is a pronounced proportion of a special subpopulation that provides a specific response to thymus-independent type II antigens, which is accompanied primarily by the synthesis of immunoglobulin M: B1a lymphocytes, some of which express the activation antigens CD38 and CD23. It is known that the precursors of these cells migrate early from the hematopoietic tissue to their anatomical niche, into the abdominal and pleural cavities, where autonomy from the central organs of the immune system is maintained by the number of its population. Some B1 cells migrate (through the omentum) to the intestinal mucosa and mesenteric lymph nodes (up to 50% of IgA producers in the lymphoid tissue of the intestinal B1 cells).

#### **3.3 Cells of the marginal zone**

Coexpression of CD38 and CD25 can be observed within the B cell population of the marginal zone of the spleen. B cells of the marginal zone (BMZ) originate from a pool of recycled B lymphocytes that have returned to the marginal zone of the spleen. Phenotypically, these cells are more similar to B2 cells than to B1 cells. They come from the same bone marrow precursor cells. Separation of the line of BMZ cells from the general line of B2 cells occurs in the transitional stage of transient cells (T3), when future BMZ cells weaken the expression of non-IgM (like B2 cells) and IgD and lose the CD23 molecule.

These cells have specific morphological features: IgM molecules are expressed on their membrane, but there are no IgD molecules [48]. IgM is expressed more strongly than on B2 cells. For BMZ, high expression of CD21 is characteristic, which allows them to successfully bind T cell-independent type 2 antigens, presented in particular on encapsulated bacteria [49]. The molecules of СD69, СD25, and СD38 in a small amount of СD23 are expressed on BMZ. B lymphocytes with this phenotype are also found in other lymphoid tissues, but only the marginal zone of the spleen accumulates the largest number of these cells in the body. At the BMZ lymphocytes, the chemokine receptor is not expressed, which allows the cells to migrate to the follicles. The cells of the marginal zone are located in the primary blood sine network of the spleen, which allows them to interact with antigens carried by the blood [38, 51]. Information on antigens of BMZ is obtained by "shuttle" migration to lymphoid follicles and back. When answering antigens, the BMZ cells differentiate into short-lived antibodyforming cells. Due to the strong expression of MHC-11 molecules and costimulatory

**143**

*Splenectomy in Gastric Cancer: Influence of B Lymphocytes*

period of their life is comparable with the life of an organism.

molecules, BMZ cells have pronounced an ability to interact with T-helper cells. The

In the spleen, there are complex processes of differentiation, selection of B lymphocytes, and replenishment of the pool of recirculating B lymphocytes and the pool of BMZ and B1 cells. To evaluate the features of the B cell link of immunity in patients with gastric cancer after gastrectomy with splenectomy, an investigation of subpopulations of B lymphocytes in the dynamics before and after the operation was carried out. Immunophenotypic profile of B cells was studied in 14 patients with gastric cancer with spleen-protective D2 lymphodissection and gastrectomy and in 16 patients with gastric cancer after gastrectomy and D2 lymphodissection

In the group of patients with spleen-protective D2 lymphodissection, a significant correlation between the relative values (the proportion of lymphocytes and leukocytes) and the absolute (cells in 1 μl of blood) in the number of CD19+ B cells was established in a pairwise comparison (T-test for paired variables) (p = 0.015, p = 0.04, and p = 0.05, respectively). The number of cells in the CD19+CD21+ population (p = 0.034) also significantly correlated before and after

In the group of patients who underwent gastrectomy with splenectomy, a significant correlation between the relative number of B lymphocytes (p = 0.018) and CD5+ B lymphocytes (p = 0.012) and the number of CD19+CD38+ cells was found in a pairwise comparison of mean values before and after surgery (p = 0.035). Three months after surgery in comparison with preoperative parameters in patients with gastric cancer after splenectomy, the percentage of cells with CD5+ expression significantly increased (t = −6.015 sig <0.0001, p = 0.013), and the relative amount of CD19+ lymphocytes and CD19+CD21+ B cells was decreased (before surgery, their number was 83.6%, and after, 73.9%, p = 0.08). The largest number of CD19+CD21+ B cells in the body is accumulated in the marginal zone of the spleen. When comparing the two groups after surgery, a high percentage of CD19+CD5+ B cells was detected (21.7 vs. 14.5%) in the group of patients with splenectomy (p = 0.049), which are precursors of functionally more advanced and

In the spleen, there are complex processes of differentiation, selection of B lymphocytes, and replenishment of the pool of recirculating B lymphocytes and the

Coexpression of CD38 and CD25 can be observed within the B cell population of the marginal zone of the spleen. B cells of the marginal zone (BMZ) originate from a pool of recycled B lymphocytes that have returned to the marginal zone of the spleen. Phenotypically, these cells are more similar to B2 cells than to B1 cells. They

These cells have specific morphological features: IgM molecules are expressed on their membrane, but there are no IgD molecules [49]. IgM is expressed more strongly than on B2 cells. For BMZ, high expression of CD21 is characteristic, which allows them to successfully bind TH2 antigens (T cell-independent type 2 antigens), presented in particular on encapsulated bacteria [50, 51]. The molecules of СD69, СD25, and СD38 in a small amount of СD23 are expressed on BMZ. B lymphocytes with this phenotype are also found in other lymphoid tissues, but only the marginal zone of the spleen accumulates the largest number of these cells in the body.

*DOI: http://dx.doi.org/10.5772/intechopen.80075*

with splenectomy.

the operation.

**4. Discussion**

pool of BMZ and B1 cells.

clonally more diverse true B cells.

come from the same bone marrow precursor cells.

*Normal and Malignant B-Cell*

than 15.0% (**Figure 3b**).

**Table 4.**

B1 cells).

**3.3 Cells of the marginal zone**

and IgD and lose the CD23 molecule.

correlation for CD1+CD5+ and CD19+CD25+ B cells, R = 0.879, p = 0.05). However, in most samples (65%), the number of CD19+CD38+ B cells was insignificant—less

*Significant populations of B cells in groups of patients with stomach cancer with (CD5+) lymphocytes* 

**Population Group 1 Group 2 Group 1/group 2** *t-***Test Relevance** CD21 85.3 ± 1.6 79.1 ± 1.9 13/27 2.436 0.02 CD25 3.9 ± 2.0 0.7 ± 0.1 11/26 2.435 0.02 CD38 27.7 ± 6.5 16.1 ± 2.9 16/38 1.858 0.07

It is interesting to note that the expression levels of the CD5 antigen on B cells proved to be significantly weaker [region R3, (**Figure 5d**)] as compared to the

Thus, in 17.7% of patients with gastric cancer in the peripheral blood, there is a pronounced proportion of a special subpopulation that provides a specific response to thymus-independent type II antigens, which is accompanied primarily by the synthesis of immunoglobulin M: B1a lymphocytes, some of which express the activation antigens CD38 and CD23. It is known that the precursors of these cells migrate early from the hematopoietic tissue to their anatomical niche, into the abdominal and pleural cavities, where autonomy from the central organs of the immune system is maintained by the number of its population. Some B1 cells migrate (through the omentum) to the intestinal mucosa and mesenteric lymph nodes (up to 50% of IgA producers in the lymphoid tissue of the intestinal

Coexpression of CD38 and CD25 can be observed within the B cell population of the marginal zone of the spleen. B cells of the marginal zone (BMZ) originate from a pool of recycled B lymphocytes that have returned to the marginal zone of the spleen. Phenotypically, these cells are more similar to B2 cells than to B1 cells. They come from the same bone marrow precursor cells. Separation of the line of BMZ cells from the general line of B2 cells occurs in the transitional stage of transient cells (T3), when future BMZ cells weaken the expression of non-IgM (like B2 cells)

These cells have specific morphological features: IgM molecules are expressed on their membrane, but there are no IgD molecules [48]. IgM is expressed more strongly than on B2 cells. For BMZ, high expression of CD21 is characteristic, which allows them to successfully bind T cell-independent type 2 antigens, presented in particular on encapsulated bacteria [49]. The molecules of СD69, СD25, and СD38 in a small amount of СD23 are expressed on BMZ. B lymphocytes with this phenotype are also found in other lymphoid tissues, but only the marginal zone of the spleen accumulates the largest number of these cells in the body. At the BMZ lymphocytes, the chemokine receptor is not expressed, which allows the cells to migrate to the follicles. The cells of the marginal zone are located in the primary blood sine network of the spleen, which allows them to interact with antigens carried by the blood [38, 51]. Information on antigens of BMZ is obtained by "shuttle" migration to lymphoid follicles and back. When answering antigens, the BMZ cells differentiate into short-lived antibodyforming cells. Due to the strong expression of MHC-11 molecules and costimulatory

expression of CD5 antigen on peripheral CD3+ T cells.

*(group 1 ≥ 15%) and their normal content (group 2 < 15%).*

**142**

molecules, BMZ cells have pronounced an ability to interact with T-helper cells. The period of their life is comparable with the life of an organism.

In the spleen, there are complex processes of differentiation, selection of B lymphocytes, and replenishment of the pool of recirculating B lymphocytes and the pool of BMZ and B1 cells. To evaluate the features of the B cell link of immunity in patients with gastric cancer after gastrectomy with splenectomy, an investigation of subpopulations of B lymphocytes in the dynamics before and after the operation was carried out. Immunophenotypic profile of B cells was studied in 14 patients with gastric cancer with spleen-protective D2 lymphodissection and gastrectomy and in 16 patients with gastric cancer after gastrectomy and D2 lymphodissection with splenectomy.

In the group of patients with spleen-protective D2 lymphodissection, a significant correlation between the relative values (the proportion of lymphocytes and leukocytes) and the absolute (cells in 1 μl of blood) in the number of CD19+ B cells was established in a pairwise comparison (T-test for paired variables) (p = 0.015, p = 0.04, and p = 0.05, respectively). The number of cells in the CD19+CD21+ population (p = 0.034) also significantly correlated before and after the operation.

In the group of patients who underwent gastrectomy with splenectomy, a significant correlation between the relative number of B lymphocytes (p = 0.018) and CD5+ B lymphocytes (p = 0.012) and the number of CD19+CD38+ cells was found in a pairwise comparison of mean values before and after surgery (p = 0.035).

Three months after surgery in comparison with preoperative parameters in patients with gastric cancer after splenectomy, the percentage of cells with CD5+ expression significantly increased (t = −6.015 sig <0.0001, p = 0.013), and the relative amount of CD19+ lymphocytes and CD19+CD21+ B cells was decreased (before surgery, their number was 83.6%, and after, 73.9%, p = 0.08). The largest number of CD19+CD21+ B cells in the body is accumulated in the marginal zone of the spleen. When comparing the two groups after surgery, a high percentage of CD19+CD5+ B cells was detected (21.7 vs. 14.5%) in the group of patients with splenectomy (p = 0.049), which are precursors of functionally more advanced and clonally more diverse true B cells.
