A cytotoxic monoclonal antibody to colon adenocarcinoma.

We have produced a monoclonal antibody CCOL1 that is cytotoxic at a titer of 1:20,000 using human sera as a complement source. CCOL1 reacts to the immunizing colon carcinoma line as well as to one other colon carcinoma line. However, it does not react with another colon adenocarcinoma line or with 28 other cultured tumor cells. It is noncytotoxic to lymphocytes, monocytes, granulocytes, RBC, and platelets. When tested by enzyme-linked immunosorbent assay against the normal cell membranes, it did not react to colon, lung, kidney cortex, heart, pancreas, liver, stomach, intestine, or kidney medulla but was strongly positive to the cell membrane of the colon adenocarcinoma line. The antibody reacted with 4 colon cancer tissue sections by immunoperoxidase. Control tissue sections of skin, spleen, kidney, brain, and uterus were negative. CCOL1 showed slight staining of epithelial cells in the tissue sections of normal lung, esophagus, colon, pancreas, and stomach. From preliminary studies, the antigen appears to be a glycoprotein, since it was highly sensitive to Pronase and sodium periodate.

Effect of physical stress on sensitivity of lymphocytes to inhibition by prostaglandin E2.

Physical stress is associated with depressed cellular immune function. We have found that lymphocytes from subjects undergoing either of 2 stressful events, cardiac surgery or childbirth, are more sensitive to inhibition by PGE2. For example, the concentration of PGE2 required for 50% inhibition of 3H-thymidine incorporation (ID50) into phytohemagglutinin-stimulated lymphocytes from patients undergoing cardiac surgery went from 1.5 X 10(-8) M on the day before surgery to 3 X 10(-9) M on the day after surgery. This increase in sensitivity to PGE2 was accompanied by a significantly decreased lymphocyte proliferative response (27 to 68% of control, depending on mitogen dose) and a 50% increase in the percentage of E rosette-positive cells with receptors for the Fc portion of IgG. The increased sensitivity to PGE and the depressed mitogen responses returned to preoperative values by day 10. The depressed mitogen responses of the postoperative patients were completely restored to normal by removal of glass-adherent cells before culture. In addition, the responses of the postoperative patients and the women in labor were partially restored by the addition of indomethacin, a prostaglandin synthetase inhibitor, to the cultures. Thus it would appear that physical stress causes lymphocytes to become more sensitive to prostaglandin E2, and the increased sensitivity to inhibition by this immunomodulator is responsible in part for the depressed cellular immune function after physical stress.

T-lymphocyte subpopulations in peripheral blood and tissues of cancer patients.

Patients with cancer often show impaired immune functions; however, the basis of this suppression is still not understood. In several experimental systems, human T-cells with receptors for Fc of immunoglobulin G may function as suppressors, and those with receptors for Fc of immunoglobulin M may function as helpers. Peripheral blood as well as tumor tissue infiltrates were examined for proportions and numbers of T gamma, T mu, or Ia-positive T-cells. Forty-five untreated patients with solid tumors and 24 patients with lymphomas were studied. An increase in the percentage of peripheral blood T gamma cells (p < 0.001) and a decrease in T mu cells (p < 0.0005) were recorded in all tumor patients when compared with 30 normal controls. Percentages and absolute numbers of peripheral blood Ia-positive T-cells were decreased (p < 0.001 and < 0.00001) in solid-tumor patients; by contrast, the proportion of peripheral blood Ia-positive T-cells was elevated (p < 0.005) in lymphoma subjects. Studies of cancer tissues from 46 untreated patients using immunofluorescence and mouse hybridoma antibody specific for T-cells showed that tumor lymphocytic infiltrates were composed mainly of T-cells. Double staining with fluorescein-conjugated specific anti-T gamma and Ia-positive T-cells within solid-tumor lymphoid infiltrates. A comparison of peripheral blood and tumor lymphocyte T-cell profiles revealed that, in some patients, low proportions of Ia-positive T-cells in blood were paralleled by a high percentage of such cells in tumor lymphoid infiltrates.

Ia antigen on the surface of a subfraction of T cells that bear Fc receptors for IgG.

Human peripheral blood T cells and T cell subpopulations were studied for the presence of Ia-like antigen, by using indirect immunofluorescence with heterologous rabbit anti-Ia antisera. In 13 normal subjects the percentage of T cells staining with the anti-Ia reagent was 2 to 5% and appeared limited to the T gamma subfraction. After concanavalin A (Con A) or phytohemagglutinin (PHA) activation, the proportion of Ia(+) T cells increased due to an increase in the percentage of T gamma cells bearing Ia-like antigen as well as an increase in the proportion of T gamma cells in the T cell fraction.

Cyclic adenosine monophosphate response to prostaglandin E2 on subpopulations of human lymphocytes.

Receptors for prostaglandin E2 or histamine were measured on subpopulations of human lymphocytes, using the cyclic AMP increase after exposure to prostaglandin or histamine as an indicator for the presence of receptors. The cyclic AMP response to prostaglandin E2 was similar in unfractionated lymphocytes and the T-enriched and T-depleted fractions. Within the T-enriched population, T cells bearing a receptor for the Fc portion of IgG (T gamma-cells) had a 27.4-fold rise in cyclic AMP after exposure to prostaglandin E2, whereas the remaining T cells (non-T gamma cells) had a fourfold increase. It would appear that prostaglandin receptors are concentrated on a small subfraction of T gamma cells, comprising approximately 15% of the T-cell population. The cyclic AMP response to histamine was less than twofold in all lymphocyte fractions.